Support tests in freestanding

Summary:
Freestanding is *weird*. The standard allows it to differ in a bunch of odd
manners from regular C++, and the committee would like to improve that
situation. I'd like to make libc++ behave better with what freestanding should
be, so that it can be a tool we use in improving the standard. To do that we
need to try stuff out, both with "freestanding the language mode" and
"freestanding the library subset".

Let's start with the super basic: run the libc++ tests in freestanding, using
clang as the compiler, and see what works. The easiest hack to do this:

In utils/libcxx/test/config.py add:

  self.cxx.compile_flags += ['-ffreestanding']

Run the tests and they all fail.

Why? Because in freestanding `main` isn't special. This "not special" property
has two effects: main doesn't get mangled, and main isn't allowed to omit its
`return` statement. The first means main gets mangled and the linker can't
create a valid executable for us to test. The second means we spew out warnings
(ew) and the compiler doesn't insert the `return` we omitted, and main just
falls of the end and does whatever undefined behavior (if you're luck, ud2
leading to non-zero return code).

Let's start my work with the basics. This patch changes all libc++ tests to
declare `main` as `int main(int, char**` so it mangles consistently (enabling us
to declare another `extern "C"` main for freestanding which calls the mangled
one), and adds `return 0;` to all places where it was missing. This touches 6124
files, and I apologize.

The former was done with The Magic Of Sed.

The later was done with a (not quite correct but decent) clang tool:

  https://gist.github.com/jfbastien/793819ff360baa845483dde81170feed

This works for most tests, though I did have to adjust a few places when e.g.
the test runs with `-x c`, macros are used for main (such as for the filesystem
tests), etc.

Once this is in we can create a freestanding bot which will prevent further
regressions. After that, we can start the real work of supporting C++
freestanding fairly well in libc++.

<rdar://problem/47754795>

Reviewers: ldionne, mclow.lists, EricWF

Subscribers: christof, jkorous, dexonsmith, arphaman, miyuki, libcxx-commits

Differential Revision: https://reviews.llvm.org/D57624

llvm-svn: 353086

426 files changed, 1270 insertions, 428 deletions

diff --git a/libcxx/test/std/input.output/file.streams/c.files/cinttypes.pass.cpp b/libcxx/test/std/input.output/file.streams/c.files/cinttypes.pass.cpp
index 675c5751650..e9e32bb6734 100644
--- a/libcxx/test/std/input.output/file.streams/c.files/cinttypes.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/c.files/cinttypes.pass.cpp
@@ -877,7 +877,7 @@ template <class T> void test()
     ((void)t); // Prevent unused warning
 }
 
-int main()
+int main(int, char**)
 {
     test<std::int8_t >();
     test<std::int16_t>();
@@ -927,4 +927,6 @@ int main()
     static_assert((std::is_same<decltype(std::strtoumax("", (char**)0, 0)), std::uintmax_t>::value), "");
     static_assert((std::is_same<decltype(std::wcstoimax(L"", (wchar_t**)0, 0)), std::intmax_t>::value), "");
     static_assert((std::is_same<decltype(std::wcstoumax(L"", (wchar_t**)0, 0)), std::uintmax_t>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/c.files/cstdio.pass.cpp b/libcxx/test/std/input.output/file.streams/c.files/cstdio.pass.cpp
index 95a5cb69512..af8dc97a5e8 100644
--- a/libcxx/test/std/input.output/file.streams/c.files/cstdio.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/c.files/cstdio.pass.cpp
@@ -85,7 +85,7 @@
 #pragma clang diagnostic ignored "-Wdeprecated-declarations"
 #endif
 
-int main()
+int main(int, char**)
 {
     std::FILE* fp = 0;
     std::fpos_t fpos = std::fpos_t();
@@ -154,4 +154,6 @@ int main()
     static_assert((std::is_same<decltype(std::puts("")), int>::value), "");
     static_assert((std::is_same<decltype(std::vprintf(" ",va)), int>::value), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/c.files/gets.fail.cpp b/libcxx/test/std/input.output/file.streams/c.files/gets.fail.cpp
index 0772dc9f0fc..dae0e42ff34 100644
--- a/libcxx/test/std/input.output/file.streams/c.files/gets.fail.cpp
+++ b/libcxx/test/std/input.output/file.streams/c.files/gets.fail.cpp
@@ -13,7 +13,9 @@
 
 #include <cstdio>
 
-int main()
+int main(int, char**)
 {
     (void) std::gets((char *) NULL);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/member_swap.pass.cpp
index b6890b8717d..9bfcec0a48f 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/member_swap.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -50,4 +50,6 @@ int main()
         assert(f2.sgetc() == L'2');
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/move_assign.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/move_assign.pass.cpp
index 0acda35b080..a397e6cc138 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/move_assign.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/move_assign.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -52,4 +52,6 @@ int main()
         assert(f2.sgetc() == L'2');
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/nonmember_swap.pass.cpp
index 6fd1d2bb471..f23c119af90 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.assign/nonmember_swap.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -52,4 +52,6 @@ int main()
         assert(f2.sgetc() == L'2');
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/default.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/default.pass.cpp
index d9230b04527..5efbb03c8a6 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/default.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::filebuf f;
@@ -26,4 +26,6 @@ int main()
         std::wfilebuf f;
         assert(!f.is_open());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/move.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/move.pass.cpp
index ad4d37dad63..922e514d7f4 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.cons/move.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -50,4 +50,6 @@ int main()
         assert(f2.sgetc() == L'2');
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_path.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_path.pass.cpp
index 7f7ce344f86..ea244e1a32d 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_path.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_path.pass.cpp
@@ -19,7 +19,7 @@
 
 namespace fs = std::filesystem;
 
-int main() {
+int main(int, char**) {
 
   fs::path p = get_temp_file_name();
   {
@@ -52,4 +52,6 @@ int main() {
     assert(f.sbumpc() == L'3');
   }
   remove(p.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_pointer.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_pointer.pass.cpp
index fc3dd6d01cd..bd662a9f7f8 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.members/open_pointer.pass.cpp
@@ -14,7 +14,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -47,4 +47,6 @@ int main()
         assert(f.sbumpc() == L'3');
     }
     remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/overflow.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/overflow.pass.cpp
index 0aeb505c75c..6636a422332 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/overflow.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/overflow.pass.cpp
@@ -36,7 +36,7 @@ struct test_buf
     virtual int_type overflow(int_type c = traits_type::eof()) {return base::overflow(c);}
 };
 
-int main()
+int main(int, char**)
 {
     {
         test_buf<char> f;
@@ -140,4 +140,6 @@ int main()
         assert(f.sbumpc() == -1);
     }
     std::remove("overflow.dat");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp
index e711b0c9b5c..728eec2938e 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/pbackfail.pass.cpp
@@ -32,7 +32,7 @@ struct test_buf
     virtual int_type pbackfail(int_type c = traits_type::eof()) {return base::pbackfail(c);}
 };
 
-int main()
+int main(int, char**)
 {
     {
         test_buf<char> f;
@@ -60,4 +60,6 @@ int main()
             assert(f.sgetc() == '2');
         }
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/seekoff.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/seekoff.pass.cpp
index 9126b3396d7..6f50357a093 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/seekoff.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/seekoff.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
         char buf[10];
@@ -62,4 +62,6 @@ int main()
         assert(f.sgetc() == L'l');
     }
     std::remove("seekoff.dat");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp
index 8859b07969d..47760a91627 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf.virtuals/underflow.pass.cpp
@@ -36,7 +36,7 @@ struct test_buf
     virtual int_type underflow() {return base::underflow();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         test_buf<char> f;
@@ -121,4 +121,6 @@ int main()
         assert(f.sbumpc() == 0x4E53);
         assert(f.sbumpc() == static_cast<Traits::int_type>(-1));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/filebuf/types.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/filebuf/types.pass.cpp
index e0c95f50a2d..40c010f6f70 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/filebuf/types.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/filebuf/types.pass.cpp
@@ -22,7 +22,7 @@
 #include <fstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_streambuf<char>, std::basic_filebuf<char> >::value), "");
     static_assert((std::is_same<std::basic_filebuf<char>::char_type, char>::value), "");
@@ -30,4 +30,6 @@ int main()
     static_assert((std::is_same<std::basic_filebuf<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_filebuf<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_filebuf<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/member_swap.pass.cpp
index 312a68d8307..7c94de924d9 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/member_swap.pass.cpp
@@ -35,7 +35,7 @@ std::pair<std::string, std::string> get_temp_file_names() {
   return names;
 }
 
-int main()
+int main(int, char**)
 {
     std::pair<std::string, std::string> temp_files = get_temp_file_names();
     std::string& temp1 = temp_files.first;
@@ -87,4 +87,6 @@ int main()
     }
     std::remove(temp1.c_str());
     std::remove(temp2.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/move_assign.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/move_assign.pass.cpp
index 4ee860a8e9f..d2cc6ce722f 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/move_assign.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/move_assign.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -46,4 +46,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/nonmember_swap.pass.cpp
index 5a2d826bea6..071ca5d85e7 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.assign/nonmember_swap.pass.cpp
@@ -37,7 +37,7 @@ std::pair<std::string, std::string> get_temp_file_names() {
   return names;
 }
 
-int main()
+int main(int, char**)
 {
     std::pair<std::string, std::string> temp_files = get_temp_file_names();
     std::string& temp1 = temp_files.first;
@@ -89,4 +89,6 @@ int main()
     }
     std::remove(temp1.c_str());
     std::remove(temp2.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/default.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/default.pass.cpp
index ede9fd2393a..b38bbb4431f 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/default.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     {
         std::fstream fs;
@@ -24,4 +24,6 @@ int main()
     {
         std::wfstream fs;
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/move.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/move.pass.cpp
index a213cc64308..fb639f1c50b 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/move.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -44,4 +44,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/path.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/path.pass.cpp
index f63ae6bddbb..d86b4b6ccf8 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/path.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/path.pass.cpp
@@ -23,7 +23,7 @@
 
 namespace fs = std::filesystem;
 
-int main() {
+int main(int, char**) {
   fs::path p = get_temp_file_name();
   {
     std::fstream fs(p, std::ios_base::in | std::ios_base::out |
@@ -45,4 +45,6 @@ int main() {
     assert(x == 3.25);
   }
   std::remove(p.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/pointer.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/pointer.pass.cpp
index 07a6a41134f..4cade955b9b 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/pointer.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/pointer.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -40,4 +40,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/string.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/string.pass.cpp
index 36546035cce..15a2c702393 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.cons/string.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -42,4 +42,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/close.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/close.pass.cpp
index 818f73be8f0..94a06c4670c 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/close.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/close.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -38,4 +38,6 @@ int main()
         assert(!fs.is_open());
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_path.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_path.pass.cpp
index d6722076a97..799829e2bb2 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_path.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_path.pass.cpp
@@ -20,7 +20,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main() {
+int main(int, char**) {
   std::filesystem::path p = get_temp_file_name();
   {
     std::fstream stream;
@@ -48,4 +48,6 @@ int main() {
     assert(x == 3.25);
   }
   std::remove(p.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_pointer.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_pointer.pass.cpp
index 07f5c18f561..32f1d0096a3 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_pointer.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -46,4 +46,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_string.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_string.pass.cpp
index 4bc436b3822..90cd5611701 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_string.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/open_string.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -46,4 +46,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/rdbuf.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/rdbuf.pass.cpp
index ecbc15bc3e5..0f39fc63b62 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/rdbuf.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream.members/rdbuf.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::fstream fs;
@@ -26,4 +26,6 @@ int main()
         std::wfstream fs;
         assert(fs.rdbuf());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/fstream/types.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/fstream/types.pass.cpp
index 3f81e18f4ba..783cfa3a736 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/fstream/types.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/fstream/types.pass.cpp
@@ -22,7 +22,7 @@
 #include <fstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_iostream<char>, std::basic_fstream<char> >::value), "");
     static_assert((std::is_same<std::basic_fstream<char>::char_type, char>::value), "");
@@ -30,4 +30,6 @@ int main()
     static_assert((std::is_same<std::basic_fstream<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_fstream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_fstream<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/member_swap.pass.cpp
index e30a9c0600d..17b88140d54 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/member_swap.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs1("test.dat");
@@ -38,4 +38,6 @@ int main()
         fs2 >> x;
         assert(x == 3.25);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/move_assign.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/move_assign.pass.cpp
index 9ccd54eec8f..d5fe0984ee6 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/move_assign.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/move_assign.pass.cpp
@@ -18,7 +18,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fso("test.dat");
@@ -36,4 +36,6 @@ int main()
         fs >> x;
         assert(x == 3.25);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/nonmember_swap.pass.cpp
index c008fe50fb7..c4cd592d11e 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.assign/nonmember_swap.pass.cpp
@@ -17,7 +17,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs1("test.dat");
@@ -39,4 +39,6 @@ int main()
         fs2 >> x;
         assert(x == 3.25);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/default.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/default.pass.cpp
index 896903d36d2..7e76d6f8aef 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/default.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs;
@@ -24,4 +24,6 @@ int main()
     {
         std::wifstream fs;
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/move.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/move.pass.cpp
index c7e389e3a70..d8a58ac53ce 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/move.pass.cpp
@@ -18,7 +18,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fso("test.dat");
@@ -34,4 +34,6 @@ int main()
         fs >> x;
         assert(x == 3.25);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/path.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/path.pass.cpp
index 7d6da5b271e..8a3a361bb39 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/path.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/path.pass.cpp
@@ -22,7 +22,7 @@
 
 namespace fs = std::filesystem;
 
-int main() {
+int main(int, char**) {
   {
     fs::path p;
     static_assert(!std::is_convertible<fs::path, std::ifstream>::value,
@@ -49,4 +49,6 @@ int main() {
   // std::wifstream(const fs::path&, std::ios_base::openmode) is tested in
   // test/std/input.output/file.streams/fstreams/ofstream.cons/string.pass.cpp
   // which creates writable files.
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/pointer.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/pointer.pass.cpp
index 6e0bb2984cc..d44b3be75d1 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/pointer.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/pointer.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs("test.dat");
@@ -36,4 +36,6 @@ int main()
     // std::wifstream(const char*, std::ios_base::openmode) is tested in
     // test/std/input.output/file.streams/fstreams/ofstream.cons/pointer.pass.cpp
     // which creates writable files.
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/string.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/string.pass.cpp
index a0d90e25595..c4e979e30c6 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.cons/string.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs(std::string("test.dat"));
@@ -36,4 +36,6 @@ int main()
     // std::wifstream(const std::string&, std::ios_base::openmode) is tested in
     // test/std/input.output/file.streams/fstreams/ofstream.cons/string.pass.cpp
     // which creates writable files.
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/close.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/close.pass.cpp
index 609ca4ac158..e72bd548763 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/close.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/close.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs;
@@ -34,4 +34,6 @@ int main()
         fs.close();
         assert(!fs.is_open());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_path.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_path.pass.cpp
index 4432ea5c621..bce5fb97dd1 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_path.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_path.pass.cpp
@@ -19,7 +19,7 @@
 #include <filesystem>
 #include <cassert>
 
-int main() {
+int main(int, char**) {
   {
     std::ifstream fs;
     assert(!fs.is_open());
@@ -44,4 +44,6 @@ int main() {
     fs >> c;
     assert(c == L'r');
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_pointer.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_pointer.pass.cpp
index 3a12c985291..50ec53fdc78 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_pointer.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs;
@@ -42,4 +42,6 @@ int main()
         fs >> c;
         assert(c == L'r');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_string.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_string.pass.cpp
index e6759ed8cae..155ae0e631d 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_string.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/open_string.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs;
@@ -42,4 +42,6 @@ int main()
         fs >> c;
         assert(c == L'r');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/rdbuf.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/rdbuf.pass.cpp
index ea64139f13e..455d2274e2b 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/rdbuf.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream.members/rdbuf.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ifstream fs("test.dat");
@@ -28,4 +28,6 @@ int main()
         std::wfilebuf* fb = fs.rdbuf();
         assert(fb->sgetc() == L'r');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ifstream/types.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ifstream/types.pass.cpp
index a3b441f9386..620c3960895 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ifstream/types.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ifstream/types.pass.cpp
@@ -22,7 +22,7 @@
 #include <fstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_istream<char>, std::basic_ifstream<char> >::value), "");
     static_assert((std::is_same<std::basic_ifstream<char>::char_type, char>::value), "");
@@ -30,4 +30,6 @@ int main()
     static_assert((std::is_same<std::basic_ifstream<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_ifstream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_ifstream<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/member_swap.pass.cpp
index 89e32e97f76..fcfb94ecf20 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/member_swap.pass.cpp
@@ -35,7 +35,7 @@ std::pair<std::string, std::string> get_temp_file_names() {
   return names;
 }
 
-int main()
+int main(int, char**)
 {
     std::pair<std::string, std::string> temp_files = get_temp_file_names();
     std::string& temp1 = temp_files.first;
@@ -95,4 +95,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp2.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/move_assign.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/move_assign.pass.cpp
index 1eba0d576a0..fbc3bf59738 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/move_assign.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/move_assign.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -48,4 +48,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/nonmember_swap.pass.cpp
index 4190db3a6c1..3cbf508d94e 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.assign/nonmember_swap.pass.cpp
@@ -36,7 +36,7 @@ std::pair<std::string, std::string> get_temp_file_names() {
   return names;
 }
 
-int main()
+int main(int, char**)
 {
     std::pair<std::string, std::string> temp_files = get_temp_file_names();
     std::string& temp1 = temp_files.first;
@@ -96,4 +96,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp2.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/default.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/default.pass.cpp
index f87bb1e7965..baa4bfe9d8a 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/default.pass.cpp
@@ -16,7 +16,7 @@
 #include <fstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     {
         std::ofstream fs;
@@ -24,4 +24,6 @@ int main()
     {
         std::wofstream fs;
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/move.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/move.pass.cpp
index 85fcffee485..3a3e11e9114 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/move.pass.cpp
@@ -19,7 +19,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -46,4 +46,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/path.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/path.pass.cpp
index bad7e4f6428..254d696aaf7 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/path.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/path.pass.cpp
@@ -22,7 +22,7 @@
 
 namespace fs = std::filesystem;
 
-int main() {
+int main(int, char**) {
   fs::path p = get_temp_file_name();
   {
     static_assert(!std::is_convertible<fs::path, std::ofstream>::value,
@@ -65,4 +65,6 @@ int main() {
     assert(x == 3.25);
   }
   std::remove(p.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/pointer.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/pointer.pass.cpp
index 5e4a18d1ed7..ce23d5e36f4 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/pointer.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/pointer.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -54,4 +54,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/string.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/string.pass.cpp
index 41e739abbe2..c19c278f457 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.cons/string.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -54,4 +54,6 @@ int main()
         assert(x == 3.25);
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/close.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/close.pass.cpp
index 00a70419153..3ea39985ecb 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/close.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/close.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -38,4 +38,6 @@ int main()
         assert(!fs.is_open());
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_path.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_path.pass.cpp
index 857b6c68f84..1b783f6d5e8 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_path.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_path.pass.cpp
@@ -22,7 +22,7 @@
 
 namespace fs = std::filesystem;
 
-int main() {
+int main(int, char**) {
   fs::path p = get_temp_file_name();
   {
     std::ofstream fs;
@@ -58,4 +58,6 @@ int main() {
     assert(c == L'a');
   }
   std::remove(p.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_pointer.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_pointer.pass.cpp
index 689622741d0..5bf58814d26 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_pointer.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -54,4 +54,6 @@ int main()
         assert(c == L'a');
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_string.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_string.pass.cpp
index 6a223891a6b..52db618e105 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_string.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/open_string.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -54,4 +54,6 @@ int main()
         assert(c == L'a');
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/rdbuf.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/rdbuf.pass.cpp
index 6e8f2fc369e..a7b51fb35d6 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/rdbuf.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream.members/rdbuf.pass.cpp
@@ -17,7 +17,7 @@
 #include <cassert>
 #include "platform_support.h"
 
-int main()
+int main(int, char**)
 {
     std::string temp = get_temp_file_name();
     {
@@ -32,4 +32,6 @@ int main()
         assert(fb->sputc(L'r') == L'r');
     }
     std::remove(temp.c_str());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/fstreams/ofstream/types.pass.cpp b/libcxx/test/std/input.output/file.streams/fstreams/ofstream/types.pass.cpp
index 1feb4214a75..231807195f1 100644
--- a/libcxx/test/std/input.output/file.streams/fstreams/ofstream/types.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/fstreams/ofstream/types.pass.cpp
@@ -22,7 +22,7 @@
 #include <fstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_ostream<char>, std::basic_ofstream<char> >::value), "");
     static_assert((std::is_same<std::basic_ofstream<char>::char_type, char>::value), "");
@@ -30,4 +30,6 @@ int main()
     static_assert((std::is_same<std::basic_ofstream<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_ofstream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_ofstream<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/file.streams/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/file.streams/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/file.streams/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/file.streams/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default.pass.cpp
index 106eb033fd5..1cb88a3510f 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default.pass.cpp
@@ -18,7 +18,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   // Default
   {
@@ -27,4 +27,6 @@ int main() {
     directory_entry e;
     assert(e.path() == path());
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default_const.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default_const.pass.cpp
index 8562312432f..0f681531a09 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default_const.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.cons/default_const.pass.cpp
@@ -19,7 +19,7 @@
 #include <type_traits>
 #include <cassert>
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   // Default
   {
@@ -28,4 +28,6 @@ int main() {
     const directory_entry e;
     assert(e.path() == path());
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/comparisons.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/comparisons.pass.cpp
index 10e8c63b6d0..12158349ef8 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/comparisons.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/comparisons.pass.cpp
@@ -74,7 +74,9 @@ void test_comparisons_simple() {
   }
 }
 
-int main() {
+int main(int, char**) {
   test_comparison_signatures();
   test_comparisons_simple();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/path.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/path.pass.cpp
index 185b0ef4a24..28bd2752ec0 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/path.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_entry/directory_entry.obs/path.pass.cpp
@@ -81,7 +81,9 @@ void test_path_conversion() {
   }
 }
 
-int main() {
+int main(int, char**) {
   test_path_method();
   test_path_conversion();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_iterator/directory_iterator.members/default_ctor.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_iterator/directory_iterator.members/default_ctor.pass.cpp
index c318bdb33f6..9f60ec28674 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_iterator/directory_iterator.members/default_ctor.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_iterator/directory_iterator.members/default_ctor.pass.cpp
@@ -22,7 +22,7 @@
 #include "test_macros.h"
 
 
-int main() {
+int main(int, char**) {
     {
         static_assert(std::is_nothrow_default_constructible<fs::directory_iterator>::value, "");
     }
@@ -31,4 +31,6 @@ int main() {
         const fs::directory_iterator d2;
         assert(d1 == d2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.directory_iterator/types.pass.cpp b/libcxx/test/std/input.output/filesystems/class.directory_iterator/types.pass.cpp
index bac6939035c..3932be0216b 100644
--- a/libcxx/test/std/input.output/filesystems/class.directory_iterator/types.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.directory_iterator/types.pass.cpp
@@ -25,7 +25,7 @@
 #include "test_macros.h"
 
 
-int main() {
+int main(int, char**) {
     using namespace fs;
     using D = directory_iterator;
     ASSERT_SAME_TYPE(D::value_type, directory_entry);
@@ -33,4 +33,6 @@ int main() {
     ASSERT_SAME_TYPE(D::pointer, const directory_entry*);
     ASSERT_SAME_TYPE(D::reference, const directory_entry&);
     ASSERT_SAME_TYPE(D::iterator_category, std::input_iterator_tag);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.file_status/file_status.cons.pass.cpp b/libcxx/test/std/input.output/filesystems/class.file_status/file_status.cons.pass.cpp
index 53c619bd8e9..74fdaaf2084 100644
--- a/libcxx/test/std/input.output/filesystems/class.file_status/file_status.cons.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.file_status/file_status.cons.pass.cpp
@@ -22,7 +22,7 @@
 #include "test_convertible.hpp"
 
 
-int main() {
+int main(int, char**) {
  using namespace fs;
   // Default ctor
   {
@@ -56,4 +56,6 @@ int main() {
     assert(f.type()  == file_type::regular);
     assert(f.permissions() == perms::owner_read);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.file_status/file_status.mods.pass.cpp b/libcxx/test/std/input.output/filesystems/class.file_status/file_status.mods.pass.cpp
index 38573beaca8..0ee9f709ba4 100644
--- a/libcxx/test/std/input.output/filesystems/class.file_status/file_status.mods.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.file_status/file_status.mods.pass.cpp
@@ -20,7 +20,7 @@
 #include <cassert>
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
 
   file_status st;
@@ -45,4 +45,6 @@ int main() {
     st.permissions(perms::owner_read);
     assert(st.permissions() == perms::owner_read);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.file_status/file_status.obs.pass.cpp b/libcxx/test/std/input.output/filesystems/class.file_status/file_status.obs.pass.cpp
index 676ceea8dcc..ec4863139f4 100644
--- a/libcxx/test/std/input.output/filesystems/class.file_status/file_status.obs.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.file_status/file_status.obs.pass.cpp
@@ -20,7 +20,7 @@
 #include <cassert>
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
 
   const file_status st(file_type::regular, perms::owner_read);
@@ -41,4 +41,6 @@ int main() {
                  "operation must return perms");
     assert(st.permissions() == perms::owner_read);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.filesystem_error/filesystem_error.members.pass.cpp b/libcxx/test/std/input.output/filesystems/class.filesystem_error/filesystem_error.members.pass.cpp
index 075a4137d3a..d9d1a03332d 100644
--- a/libcxx/test/std/input.output/filesystems/class.filesystem_error/filesystem_error.members.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.filesystem_error/filesystem_error.members.pass.cpp
@@ -94,8 +94,10 @@ void test_signatures()
   }
 }
 
-int main() {
+int main(int, char**) {
   static_assert(std::is_base_of<std::system_error, fs::filesystem_error>::value, "");
   test_constructors();
   test_signatures();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.itr/iterator.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.itr/iterator.pass.cpp
index de1e413be24..558206d7082 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.itr/iterator.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.itr/iterator.pass.cpp
@@ -97,8 +97,10 @@ void checkBeginEndBasic() {
 
 }
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   checkIteratorConcepts();
   checkBeginEndBasic(); // See path.decompose.pass.cpp for more tests.
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.append.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.append.pass.cpp
index fb74c8e1946..2f468e59554 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.append.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.append.pass.cpp
@@ -311,7 +311,7 @@ void test_sfinae()
   }
 }
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   for (auto const & TC : Cases) {
@@ -335,4 +335,6 @@ int main()
     doAppendSourceAllocTest<wchar_t>(TC);
   }
   test_sfinae();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/braced_init.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/braced_init.pass.cpp
index eb45c0981d4..aff89f27bd3 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/braced_init.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/braced_init.pass.cpp
@@ -22,9 +22,11 @@
 #include "count_new.hpp"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   path p("abc");
   p = {};
   assert(p.native() == "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/copy.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/copy.pass.cpp
index 04b8f63cbdd..9265c70f6f4 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/copy.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/copy.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   static_assert(std::is_copy_assignable<path>::value, "");
   static_assert(!std::is_nothrow_copy_assignable<path>::value, "should not be noexcept");
@@ -32,4 +32,6 @@ int main() {
   assert(p.native() == s);
   assert(p2.native() == s);
   assert(&pref == &p2);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/move.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/move.pass.cpp
index 12422c68e42..5e5fb1e0e06 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/move.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/move.pass.cpp
@@ -22,7 +22,7 @@
 #include "count_new.hpp"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   static_assert(std::is_nothrow_move_assignable<path>::value, "");
   assert(globalMemCounter.checkOutstandingNewEq(0));
@@ -38,4 +38,6 @@ int main() {
     assert(p.native() != s); // Testing moved from state
     assert(&pref == &p2);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/source.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/source.pass.cpp
index edc0b263844..9c23e3b3ebf 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/source.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.assign/source.pass.cpp
@@ -228,7 +228,7 @@ void RunStringMoveTest(const char* Expect) {
   }
 }
 
-int main() {
+int main(int, char**) {
   for (auto const& MS : PathList) {
     RunTestCase<char>(MS);
     RunTestCase<wchar_t>(MS);
@@ -237,4 +237,6 @@ int main() {
     RunStringMoveTest(MS);
   }
   test_sfinae();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.compare.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.compare.pass.cpp
index 41efb7513fa..165e62fe4fe 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.compare.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.compare.pass.cpp
@@ -184,7 +184,9 @@ void test_compare_elements() {
   }
 }
 
-int main() {
+int main(int, char**) {
   test_compare_basic();
   test_compare_elements();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.concat.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.concat.pass.cpp
index 842d70543a0..b074e831e15 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.concat.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.concat.pass.cpp
@@ -325,7 +325,7 @@ void test_sfinae() {
   }
 }
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   for (auto const & TC : Cases) {
@@ -384,4 +384,6 @@ int main()
     doConcatECharTest<char32_t>(TC);
   }
   test_sfinae();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/copy.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/copy.pass.cpp
index 789789779a4..1490c0b9fed 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/copy.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/copy.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   static_assert(std::is_copy_constructible<path>::value, "");
   static_assert(!std::is_nothrow_copy_constructible<path>::value, "should not be noexcept");
@@ -30,4 +30,6 @@ int main() {
   path p2(p);
   assert(p.native() == s);
   assert(p2.native() == s);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/default.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/default.pass.cpp
index 203c0e5ee61..b31728da1f9 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/default.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/default.pass.cpp
@@ -21,9 +21,11 @@
 #include "test_macros.h"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   static_assert(std::is_nothrow_default_constructible<path>::value, "");
   const path p;
   assert(p.empty());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/move.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/move.pass.cpp
index 4382de14170..494a77c3c86 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/move.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/move.pass.cpp
@@ -22,7 +22,7 @@
 #include "count_new.hpp"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   static_assert(std::is_nothrow_move_constructible<path>::value, "");
   assert(globalMemCounter.checkOutstandingNewEq(0));
@@ -36,4 +36,6 @@ int main() {
     assert(p2.native() == s);
     assert(p.native() != s); // Testing moved from state
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/source.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/source.pass.cpp
index b10d3aa88cd..bcb9986cec9 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/source.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.construct/source.pass.cpp
@@ -117,7 +117,7 @@ void test_sfinae() {
   }
 }
 
-int main() {
+int main(int, char**) {
   for (auto const& MS : PathList) {
     RunTestCase<char>(MS);
     RunTestCase<wchar_t>(MS);
@@ -125,4 +125,6 @@ int main() {
     RunTestCase<char32_t>(MS);
   }
   test_sfinae();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/empty.fail.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/empty.fail.cpp
index 481ffcde60f..5248f67515a 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/empty.fail.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/empty.fail.cpp
@@ -20,8 +20,10 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     fs::path c;
     c.empty();  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/path.decompose.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/path.decompose.pass.cpp
index aa511cdf014..be9cefb76a8 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/path.decompose.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.decompose/path.decompose.pass.cpp
@@ -208,8 +208,10 @@ void decompFilenameTest()
   }
 }
 
-int main()
+int main(int, char**)
 {
   decompPathTest();
   decompFilenameTest();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_normal.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_normal.pass.cpp
index 4d295eec5e6..f1e616542e9 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_normal.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_normal.pass.cpp
@@ -26,7 +26,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main() {
+int main(int, char**) {
   // clang-format off
   struct {
     std::string input;
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_relative_and_proximate.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_relative_and_proximate.pass.cpp
index 96fa1597b02..7e31956ee50 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_relative_and_proximate.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.gen/lexically_relative_and_proximate.pass.cpp
@@ -27,7 +27,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main() {
+int main(int, char**) {
   // clang-format off
   struct {
     std::string input;
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/generic_string_alloc.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/generic_string_alloc.pass.cpp
index 7cb81ca0008..707a7010ffb 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/generic_string_alloc.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/generic_string_alloc.pass.cpp
@@ -33,7 +33,7 @@ MultiStringType longString = MKSTR("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQR
 // generic_string<C, T, A> forwards to string<C, T, A>. Tests for
 // string<C, T, A>() are in "path.native.op/string_alloc.pass.cpp".
 // generic_string is minimally tested here.
-int main()
+int main(int, char**)
 {
   using namespace fs;
   using CharT = wchar_t;
@@ -51,4 +51,6 @@ int main()
     assert(Alloc::alloc_count > 0);
     assert(Alloc::outstanding_alloc() == 1);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/named_overloads.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/named_overloads.pass.cpp
index 2e33769cdb3..04ae673ac48 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/named_overloads.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.generic.obs/named_overloads.pass.cpp
@@ -31,7 +31,7 @@
 
 MultiStringType longString = MKSTR("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/123456789/abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   auto const& MS = longString;
@@ -57,4 +57,6 @@ int main()
     std::u32string s = p.generic_u32string();
     assert(s == (const char32_t*)MS);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/clear.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/clear.pass.cpp
index a224dddfa97..01538539faf 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/clear.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/clear.pass.cpp
@@ -24,7 +24,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   {
     path p;
@@ -40,4 +40,6 @@ int main() {
     p2.clear();
     assert(p2.empty());
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/make_preferred.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/make_preferred.pass.cpp
index 43393aba5da..4530ef87554 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/make_preferred.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/make_preferred.pass.cpp
@@ -39,7 +39,7 @@ const MakePreferredTestcase TestCases[] =
     , {"\\foo\\/bar\\/baz\\"}
   };
 
-int main()
+int main(int, char**)
 {
   // This operation is an identity operation on linux.
   using namespace fs;
@@ -50,4 +50,6 @@ int main()
     assert(p.native() == TC.value);
     assert(&Ref == &p);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/remove_filename.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/remove_filename.pass.cpp
index 42191379dbb..7cb562c227f 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/remove_filename.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/remove_filename.pass.cpp
@@ -57,7 +57,7 @@ const RemoveFilenameTestcase TestCases[] =
     , {"bar/../baz/./file.txt", "bar/../baz/./"}
   };
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   for (auto const & TC : TestCases) {
@@ -69,4 +69,6 @@ int main()
     assert(&Ref == &p);
     assert(!p.has_filename());
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_extension.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_extension.pass.cpp
index 70040c48ae5..6fec420baa0 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_extension.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_extension.pass.cpp
@@ -51,7 +51,7 @@ const ReplaceExtensionTestcase NoArgCases[] =
     , {"foo..cpp", "foo.", ""}
 };
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   for (auto const & TC : TestCases) {
@@ -68,4 +68,6 @@ int main()
     assert(p == TC.expect);
     assert(&Ref == &p);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_filename.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_filename.pass.cpp
index 3635352210b..8142e790731 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_filename.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/replace_filename.pass.cpp
@@ -47,7 +47,7 @@ const ReplaceFilenameTestcase TestCases[] =
     , {"/foo\\baz/bong", "/foo\\baz/bar", "bar"}
   };
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   for (auto const & TC : TestCases) {
@@ -67,4 +67,6 @@ int main()
       ASSERT_EQ(p, p2);
     }
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/swap.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/swap.pass.cpp
index ac623dbfcc5..2e9dac5e438 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/swap.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.modifiers/swap.pass.cpp
@@ -41,7 +41,7 @@ const SwapTestcase TestCases[] =
 #undef LONG_STR1
 #undef LONG_STR2
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   {
@@ -76,4 +76,6 @@ int main()
     }
     assert(p1 == Val);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/c_str.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/c_str.pass.cpp
index 3f2fac696da..8b35ee8c80a 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/c_str.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/c_str.pass.cpp
@@ -23,7 +23,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   const char* const value = "hello world";
@@ -38,4 +38,6 @@ int main()
     assert(p.c_str() == str_value);
     assert(p.native().c_str() == p.c_str());
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/named_overloads.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/named_overloads.pass.cpp
index 0d747b18895..c06de9795e3 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/named_overloads.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/named_overloads.pass.cpp
@@ -32,7 +32,7 @@
 
 MultiStringType longString = MKSTR("abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ/123456789/abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ");
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   auto const& MS = longString;
@@ -58,4 +58,6 @@ int main()
     std::u32string s = p.u32string();
     assert(s == (const char32_t*)MS);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/native.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/native.pass.cpp
index 14feaf13e8e..3b88b5d6c64 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/native.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/native.pass.cpp
@@ -22,7 +22,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   const char* const value = "hello world";
@@ -35,4 +35,6 @@ int main()
     path p(value);
     assert(p.native() == value);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/operator_string.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/operator_string.pass.cpp
index 53fdcc16034..9f0069051fd 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/operator_string.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/operator_string.pass.cpp
@@ -23,7 +23,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   using string_type = path::string_type;
@@ -42,4 +42,6 @@ int main()
     assert(s == value);
     assert(p == value);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/string_alloc.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/string_alloc.pass.cpp
index 86453f8d0b9..4ace380b873 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/string_alloc.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.native.obs/string_alloc.pass.cpp
@@ -116,7 +116,7 @@ void doLongStringTest(MultiStringType const& MS) {
   /////////////////////////////////////////////////////////////////////////////
 }
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   {
@@ -133,4 +133,6 @@ int main()
     doLongStringTest<char16_t>(S);
     doLongStringTest<char32_t>(S);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.query/tested_in_path_decompose.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.query/tested_in_path_decompose.pass.cpp
index d825788506b..32c37e7f7a5 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.member/path.query/tested_in_path_decompose.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.member/path.query/tested_in_path_decompose.pass.cpp
@@ -28,4 +28,6 @@
 // bool is_relative() const;
 
 // tested in path.decompose
-int main() {}
+int main(int, char**) {
+  return 0;
+}
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.fail.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.fail.cpp
index 7b5082c8f8d..bcc4758f45f 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.fail.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.fail.cpp
@@ -20,7 +20,9 @@ struct ConvToPath {
   }
 };
 
-int main() {
+int main(int, char**) {
   ConvToPath LHS, RHS;
   (void)(LHS / RHS); // expected-error {{invalid operands to binary expression}}
+
+  return 0;
 }
\ No newline at end of file
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.pass.cpp
index 2c7042e9b7b..67af37686df 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/append_op.pass.cpp
@@ -20,7 +20,7 @@
 #include "filesystem_test_helper.hpp"
 
 // This is mainly tested via the member append functions.
-int main()
+int main(int, char**)
 {
   using namespace fs;
   path p1("abc");
@@ -30,4 +30,6 @@ int main()
 
   path p4 = p1 / "def";
   assert(p4 == "abc/def");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops.fail.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops.fail.cpp
index 287e315237b..8f1732186d8 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops.fail.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops.fail.cpp
@@ -21,7 +21,7 @@ struct ConvToPath {
   }
 };
 
-int main() {
+int main(int, char**) {
   ConvToPath LHS, RHS;
   (void)(LHS == RHS); // expected-error {{invalid operands to binary expression}}
   (void)(LHS != RHS); // expected-error {{invalid operands to binary expression}}
@@ -29,4 +29,6 @@ int main() {
   (void)(LHS <= RHS); // expected-error {{invalid operands to binary expression}}
   (void)(LHS > RHS); // expected-error {{invalid operands to binary expression}}
   (void)(LHS >= RHS); // expected-error {{invalid operands to binary expression}}
+
+  return 0;
 }
\ No newline at end of file
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops_tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops_tested_elsewhere.pass.cpp
index 3728db5f224..c61a5a0254c 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops_tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/comparison_ops_tested_elsewhere.pass.cpp
@@ -10,4 +10,6 @@
 
 // The comparison operators are tested as part of [path.compare]
 // in class.path/path.members/path.compare.pass.cpp
-int main() {}
+int main(int, char**) {
+  return 0;
+}
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/hash_value_tested_elswhere.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/hash_value_tested_elswhere.pass.cpp
index 6cf310be88b..49d28daf98f 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/hash_value_tested_elswhere.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/hash_value_tested_elswhere.pass.cpp
@@ -10,4 +10,6 @@
 
 // The "hash_value" function is tested as part of [path.compare]
 // in class.path/path.members/path.compare.pass.cpp
-int main() {}
+int main(int, char**) {
+  return 0;
+}
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp
index 54d0799d92a..557849ca8e6 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.factory.pass.cpp
@@ -25,7 +25,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main()
+int main(int, char**)
 {
   using namespace fs;
   const char* In1 = "abcd/efg";
@@ -48,4 +48,6 @@ int main()
     path p = fs::u8path(In3, In3End);
     assert(p == In1);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.pass.cpp
index 375e45da8e6..31eea925a5d 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.pass.cpp
@@ -88,10 +88,12 @@ void test_LWG2989() {
   static_assert(!is_istreamable<decltype(std::wcin), std::string>::value, "");
 }
 
-int main() {
+int main(int, char**) {
   doIOTest<char>();
   doIOTest<wchar_t>();
   //doIOTest<char16_t>();
   //doIOTest<char32_t>();
   test_LWG2989();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.unicode_bug.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.unicode_bug.pass.cpp
index 2072a9450fb..c5bb6bf120f 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.unicode_bug.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/path.io.unicode_bug.pass.cpp
@@ -62,7 +62,9 @@ void doIOTest() {
 }
 
 
-int main() {
+int main(int, char**) {
   doIOTest<char16_t>();
   doIOTest<char32_t>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/swap.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/swap.pass.cpp
index 66d854f00b2..51bb03e9f7c 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/swap.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/path.nonmember/swap.pass.cpp
@@ -22,7 +22,7 @@
 
 
 // NOTE: this is tested in path.members/path.modifiers via the member swap.
-int main()
+int main(int, char**)
 {
   using namespace fs;
   const char* value1 = "foo/bar/baz";
@@ -45,4 +45,6 @@ int main()
     assert(p1.native() == value1);
     assert(p2.native() == value2);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/class.path/synop.pass.cpp b/libcxx/test/std/input.output/filesystems/class.path/synop.pass.cpp
index 9b91651e08f..8aa186e32ae 100644
--- a/libcxx/test/std/input.output/filesystems/class.path/synop.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/class.path/synop.pass.cpp
@@ -23,7 +23,7 @@
 #include "test_macros.h"
 
 
-int main() {
+int main(int, char**) {
   using namespace fs;
   ASSERT_SAME_TYPE(path::value_type, char);
   ASSERT_SAME_TYPE(path::string_type, std::basic_string<path::value_type>);
@@ -34,4 +34,6 @@ int main() {
     const char* dummy = &path::preferred_separator;
     ((void)dummy);
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.enum/enum.copy_options.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.enum/enum.copy_options.pass.cpp
index 25f63a92b33..b949960df11 100644
--- a/libcxx/test/std/input.output/filesystems/fs.enum/enum.copy_options.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.enum/enum.copy_options.pass.cpp
@@ -22,7 +22,7 @@
 
 constexpr fs::copy_options ME(int val) { return static_cast<fs::copy_options>(val); }
 
-int main() {
+int main(int, char**) {
   typedef fs::copy_options E;
   static_assert(std::is_enum<E>::value, "");
 
@@ -59,4 +59,6 @@ int main() {
           E::create_symlinks     == ME(128) &&
           E::create_hard_links   == ME(256),
         "Expected enumeration values do not match");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.enum/enum.directory_options.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.enum/enum.directory_options.pass.cpp
index 54574f720f5..43b0945978e 100644
--- a/libcxx/test/std/input.output/filesystems/fs.enum/enum.directory_options.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.enum/enum.directory_options.pass.cpp
@@ -23,7 +23,7 @@
 
 constexpr fs::directory_options ME(int val) { return static_cast<fs::directory_options>(val); }
 
-int main() {
+int main(int, char**) {
   typedef fs::directory_options E;
   static_assert(std::is_enum<E>::value, "");
 
@@ -41,4 +41,6 @@ int main() {
         E::skip_permission_denied   == ME(2),
         "Expected enumeration values do not match");
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.enum/enum.file_type.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.enum/enum.file_type.pass.cpp
index d2162d08383..c1f16079a5d 100644
--- a/libcxx/test/std/input.output/filesystems/fs.enum/enum.file_type.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.enum/enum.file_type.pass.cpp
@@ -21,7 +21,7 @@
 
 constexpr fs::file_type ME(int val) { return static_cast<fs::file_type>(val); }
 
-int main() {
+int main(int, char**) {
   typedef fs::file_type E;
   static_assert(std::is_enum<E>::value, "");
 
@@ -43,4 +43,6 @@ int main() {
           E::socket == ME(7) &&
           E::unknown == ME(8),
         "Expected enumeration values do not match");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.enum/enum.path.format.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.enum/enum.path.format.pass.cpp
index fc11e8a9c1f..d60225d4ff6 100644
--- a/libcxx/test/std/input.output/filesystems/fs.enum/enum.path.format.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.enum/enum.path.format.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main() {
+int main(int, char**) {
   typedef fs::path::format E;
   static_assert(std::is_enum<E>::value, "");
 
@@ -34,4 +34,6 @@ int main() {
           E::auto_format   != E::generic_format &&
           E::native_format != E::generic_format,
         "Expected enumeration values are not unique");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.enum/enum.perm_options.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.enum/enum.perm_options.pass.cpp
index 117c35875e0..1fd353d041f 100644
--- a/libcxx/test/std/input.output/filesystems/fs.enum/enum.perm_options.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.enum/enum.perm_options.pass.cpp
@@ -25,7 +25,7 @@ constexpr fs::perm_options ME(int val) {
   return static_cast<fs::perm_options>(val);
 }
 
-int main() {
+int main(int, char**) {
   typedef fs::perm_options E;
   static_assert(std::is_enum<E>::value, "");
 
@@ -44,4 +44,6 @@ int main() {
         E::remove   == ME(4) &&
         E::nofollow == ME(8),
         "Expected enumeration values do not match");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.enum/enum.perms.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.enum/enum.perms.pass.cpp
index e043c87e5c1..93b5278fdd4 100644
--- a/libcxx/test/std/input.output/filesystems/fs.enum/enum.perms.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.enum/enum.perms.pass.cpp
@@ -23,7 +23,7 @@
 
 constexpr fs::perms ME(int val) { return static_cast<fs::perms>(val); }
 
-int main() {
+int main(int, char**) {
   typedef fs::perms E;
   static_assert(std::is_enum<E>::value, "");
 
@@ -60,4 +60,6 @@ int main() {
         E::mask         == ME(07777) &&
         E::unknown      == ME(0xFFFF),
         "Expected enumeration values do not match");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.error.report/tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.error.report/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/filesystems/fs.error.report/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.error.report/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.filesystem.synopsis/file_time_type.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.filesystem.synopsis/file_time_type.pass.cpp
index 6606c9a27cf..e88ef1d12c4 100644
--- a/libcxx/test/std/input.output/filesystems/fs.filesystem.synopsis/file_time_type.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.filesystem.synopsis/file_time_type.pass.cpp
@@ -39,7 +39,9 @@ void test_time_point_resolution_and_range() {
   ASSERT_SAME_TYPE(Period, std::nano);
 }
 
-int main() {
+int main(int, char**) {
   test_trivial_clock();
   test_time_point_resolution_and_range();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.weakly_canonical/weakly_canonical.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.weakly_canonical/weakly_canonical.pass.cpp
index c655490acf8..94a8e13bc08 100644
--- a/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.weakly_canonical/weakly_canonical.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.op.funcs/fs.op.weakly_canonical/weakly_canonical.pass.cpp
@@ -25,7 +25,7 @@
 #include "filesystem_test_helper.hpp"
 
 
-int main() {
+int main(int, char**) {
   // clang-format off
   struct {
     std::string input;
diff --git a/libcxx/test/std/input.output/filesystems/fs.req.macros/feature_macro.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.req.macros/feature_macro.pass.cpp
index aa1933cc6b1..dad1868bee3 100644
--- a/libcxx/test/std/input.output/filesystems/fs.req.macros/feature_macro.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.req.macros/feature_macro.pass.cpp
@@ -25,4 +25,6 @@
 #endif
 #endif
 
-int main() { }
+int main(int, char**) { 
+  return 0;
+}
diff --git a/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.fail.cpp b/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.fail.cpp
index e3030995de1..641621e7338 100644
--- a/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.fail.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.fail.cpp
@@ -23,6 +23,8 @@ using namespace std::filesystem;
 // expected-error@-5 {{expected namespace name}}
 #endif
 
-int main() {
+int main(int, char**) {
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.pass.cpp b/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.pass.cpp
index 96ba646ffbe..65864336901 100644
--- a/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.pass.cpp
+++ b/libcxx/test/std/input.output/filesystems/fs.req.namespace/namespace.pass.cpp
@@ -17,9 +17,11 @@
 
 using namespace std::filesystem;
 
-int main() {
+int main(int, char**) {
   static_assert(std::is_same<
           path,
           std::filesystem::path
       >::value, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/input.output.general/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/input.output.general/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/input.output.general/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/input.output.general/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/ext.manip/get_money.pass.cpp b/libcxx/test/std/input.output/iostream.format/ext.manip/get_money.pass.cpp
index 0a68da1c44f..cb1f2c68ee5 100644
--- a/libcxx/test/std/input.output/iostream.format/ext.manip/get_money.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/ext.manip/get_money.pass.cpp
@@ -38,7 +38,7 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("  -$1,234,567.89");
@@ -72,4 +72,6 @@ int main()
         is >> std::get_money(x, true);
         assert(x == -123456789);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/ext.manip/get_time.pass.cpp b/libcxx/test/std/input.output/iostream.format/ext.manip/get_time.pass.cpp
index 05ed05c39f7..ebf62c08e72 100644
--- a/libcxx/test/std/input.output/iostream.format/ext.manip/get_time.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/ext.manip/get_time.pass.cpp
@@ -38,7 +38,7 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("  Sat Dec 31 23:55:59 2061");
@@ -72,4 +72,6 @@ int main()
         assert(is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/ext.manip/put_money.pass.cpp b/libcxx/test/std/input.output/iostream.format/ext.manip/put_money.pass.cpp
index 0dffdfb5fe1..d924d77bc7d 100644
--- a/libcxx/test/std/input.output/iostream.format/ext.manip/put_money.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/ext.manip/put_money.pass.cpp
@@ -50,7 +50,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -88,4 +88,6 @@ int main()
         os << std::put_money(x, true);
         assert(sb.str() == L"-USD 1,234,567.89");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/ext.manip/put_time.pass.cpp b/libcxx/test/std/input.output/iostream.format/ext.manip/put_time.pass.cpp
index 7dcbcf48838..faa99e06343 100644
--- a/libcxx/test/std/input.output/iostream.format/ext.manip/put_time.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/ext.manip/put_time.pass.cpp
@@ -50,7 +50,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -83,4 +83,6 @@ int main()
         os << std::put_time(&t, L"%a %b %d %H:%M:%S %Y");
         assert(sb.str() == L"Sat Dec 31 23:55:59 2061");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/member_swap.pass.cpp
index b9505c76ed0..44b394b8fb0 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/member_swap.pass.cpp
@@ -33,7 +33,7 @@ struct test_iostream
     void swap(test_iostream& s) {base::swap(s);}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb1;
@@ -81,4 +81,6 @@ int main()
         assert(is2.precision() == 6);
         assert(is2.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/move_assign.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/move_assign.pass.cpp
index f53411270b5..c7918ec8d73 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/move_assign.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.assign/move_assign.pass.cpp
@@ -38,7 +38,7 @@ struct test_iostream
 };
 
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb1;
@@ -86,4 +86,6 @@ int main()
         assert(is2.precision() == 6);
         assert(is2.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/move.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/move.pass.cpp
index 2dc91457ce7..611a7a670d2 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/move.pass.cpp
@@ -38,7 +38,7 @@ struct test_iostream
 };
 
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -72,4 +72,6 @@ int main()
         assert(is.precision() == 6);
         assert(is.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/streambuf.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/streambuf.pass.cpp
index bf6fe65badc..c12abc0e2dc 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.cons/streambuf.pass.cpp
@@ -23,7 +23,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -51,4 +51,6 @@ int main()
         assert(is.getloc().name() == "C");
         assert(is.gcount() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.dest/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.dest/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.dest/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/iostream.dest/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/types.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/types.pass.cpp
index ef7dcd24e3b..46d7a16aac7 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/types.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/iostreamclass/types.pass.cpp
@@ -24,7 +24,7 @@
 #include <istream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_istream<char>, std::basic_iostream<char> >::value), "");
     static_assert((std::is_base_of<std::basic_ostream<char>, std::basic_iostream<char> >::value), "");
@@ -33,4 +33,6 @@ int main()
     static_assert((std::is_same<std::basic_iostream<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_iostream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_iostream<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/bool.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/bool.pass.cpp
index 570aeaa393c..799ec5eaeb5 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/bool.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/bool.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/double.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/double.pass.cpp
index 6a285556d81..9f9872d9ef8 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/double.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/double.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/float.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/float.pass.cpp
index da93a3bafc2..c2b937a89cf 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/float.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/float.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/int.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/int.pass.cpp
index f683bee45da..702287be79e 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/int.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/int.pass.cpp
@@ -41,7 +41,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -76,4 +76,6 @@ int main()
         assert(!is.eof());
         assert( is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long.pass.cpp
index 0c8eee50d75..9f9118cbcdc 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_double.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_double.pass.cpp
index 2fff174cbcc..bdd30190a5b 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_double.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_double.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_long.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_long.pass.cpp
index 6529ad333f5..1612468f4d7 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/long_long.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/pointer.pass.cpp
index 3c8a0783fa4..0893d8cdec2 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/pointer.pass.cpp
@@ -44,7 +44,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -97,4 +97,6 @@ int main()
         assert( is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/short.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/short.pass.cpp
index bc28ec29ba9..a0d96c3983f 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/short.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/short.pass.cpp
@@ -41,7 +41,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -76,4 +76,6 @@ int main()
         assert(!is.eof());
         assert( is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_int.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_int.pass.cpp
index 8bbb636e6e8..578cfcf0cc4 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_int.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_int.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long.pass.cpp
index 5635339a816..f1c150d7920 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long_long.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long_long.pass.cpp
index 402d3eab0ad..068d31ac8fb 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long_long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_long_long.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_short.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_short.pass.cpp
index cedd6a6c8af..9906bbeac8d 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_short.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.arithmetic/unsigned_short.pass.cpp
@@ -40,7 +40,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(!is.eof());
         assert(!is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.reqmts/tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.reqmts/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.reqmts/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream.formatted.reqmts/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/basic_ios.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/basic_ios.pass.cpp
index fadc70943db..704c4997d52 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/basic_ios.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/basic_ios.pass.cpp
@@ -27,11 +27,13 @@ f(std::basic_ios<CharT>& is)
     return is;
 }
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
         is >> f;
         assert(f_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/chart.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/chart.pass.cpp
index 51e0aab1a42..cbb606cdcff 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/chart.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/chart.pass.cpp
@@ -38,7 +38,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("          ");
@@ -83,4 +83,6 @@ int main()
         assert(!is.fail());
         assert(c == L'c');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/ios_base.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/ios_base.pass.cpp
index 31023cca89f..ec25dc5a7e0 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/ios_base.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/ios_base.pass.cpp
@@ -25,11 +25,13 @@ f(std::ios_base& is)
     return is;
 }
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
         is >> f;
         assert(f_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/istream.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/istream.pass.cpp
index 36ea25dafc8..f3829c25ac4 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/istream.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/istream.pass.cpp
@@ -27,11 +27,13 @@ f(std::basic_istream<CharT>& is)
     return is;
 }
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((std::streambuf*)0);
         is >> f;
         assert(f_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char.pass.cpp
index 293cd8b459a..bd06de6a07b 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char.pass.cpp
@@ -38,7 +38,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("          ");
@@ -66,4 +66,6 @@ int main()
         assert(!is.fail());
         assert(c == 'c');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char_pointer.pass.cpp
index 55db22bce7e..d5128339a71 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/signed_char_pointer.pass.cpp
@@ -38,7 +38,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("   abcdefghijk    ");
@@ -103,4 +103,6 @@ int main()
         assert(std::string((char*)s) == "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/streambuf.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/streambuf.pass.cpp
index dbc6e2398df..9feb826906f 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/streambuf.pass.cpp
@@ -55,7 +55,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("testing...");
@@ -65,4 +65,6 @@ int main()
         assert(sb2.str() == "testing...");
         assert(is.gcount() == 10);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char.pass.cpp
index 17aff9fd8de..3eceaaeb63f 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char.pass.cpp
@@ -38,7 +38,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("          ");
@@ -66,4 +66,6 @@ int main()
         assert(!is.fail());
         assert(c == 'c');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char_pointer.pass.cpp
index 1873d70fbb2..14b2993148d 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/unsigned_char_pointer.pass.cpp
@@ -38,7 +38,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("   abcdefghijk    ");
@@ -103,4 +103,6 @@ int main()
         assert(std::string((char*)s) == "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/wchar_t_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/wchar_t_pointer.pass.cpp
index cc06149b36e..f0a9e0710fb 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/wchar_t_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/istream_extractors/wchar_t_pointer.pass.cpp
@@ -38,7 +38,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("   abcdefghijk    ");
@@ -114,4 +114,6 @@ int main()
         assert(std::string(s) == "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.formatted/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.manip/ws.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.manip/ws.pass.cpp
index a1ab81a9553..6786ebf4ca0 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.manip/ws.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.manip/ws.pass.cpp
@@ -39,7 +39,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("   123");
@@ -75,4 +75,6 @@ int main()
         assert(is.eof());
         assert(is.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.rvalue/rvalue.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.rvalue/rvalue.pass.cpp
index cd46b14fdde..8d0af734703 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.rvalue/rvalue.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.rvalue/rvalue.pass.cpp
@@ -47,7 +47,7 @@ struct A{};
 bool called = false;
 void operator>>(std::istream&, A&&){ called = true; }
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("   123");
@@ -68,4 +68,6 @@ int main()
         assert(&out == &ss);
         assert(called);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get.pass.cpp
index b73a2fe72d8..40a04174133 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get.pass.cpp
@@ -37,7 +37,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("          ");
@@ -96,4 +96,6 @@ int main()
         assert(c == L'c');
         assert(is.gcount() == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_chart.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_chart.pass.cpp
index 86189b26049..ae31c9be06d 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_chart.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_chart.pass.cpp
@@ -37,7 +37,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("          ");
@@ -99,4 +99,6 @@ int main()
         assert(c == L'c');
         assert(is.gcount() == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size.pass.cpp
index ca2827aa0bd..149392cae3f 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size.pass.cpp
@@ -48,7 +48,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("  \n    \n ");
@@ -158,4 +158,6 @@ int main()
         assert(is.gcount() == 1);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp
index efaf168d6d6..e7c96d6a266 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_pointer_size_chart.pass.cpp
@@ -48,7 +48,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("  *    * ");
@@ -158,4 +158,6 @@ int main()
         assert(is.gcount() == 1);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf.pass.cpp
index 35495ef953b..dda59d7ff50 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf.pass.cpp
@@ -52,7 +52,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("testing\n...");
@@ -84,4 +84,6 @@ int main()
         assert(!is.fail());
         assert(is.gcount() == 3);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf_chart.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf_chart.pass.cpp
index 514cd2e7f6c..a1e46c2336c 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf_chart.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/get_streambuf_chart.pass.cpp
@@ -53,7 +53,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("testing*...");
@@ -85,4 +85,6 @@ int main()
         assert(!is.fail());
         assert(is.gcount() == 3);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size.pass.cpp
index 5fa822cd187..9c91053ebdb 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size.pass.cpp
@@ -48,7 +48,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("  \n    \n ");
@@ -142,4 +142,6 @@ int main()
         assert(is.gcount() == 1);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size_chart.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size_chart.pass.cpp
index 1cd19c0e1dd..bee1976e95e 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size_chart.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/getline_pointer_size_chart.pass.cpp
@@ -48,7 +48,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("  *    * ");
@@ -142,4 +142,6 @@ int main()
         assert(is.gcount() == 1);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.pass.cpp
index 99f35aac407..7f6348b01a4 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore.pass.cpp
@@ -38,7 +38,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 1\n2345\n6");
@@ -72,4 +72,6 @@ int main()
         assert(!is.fail());
         assert(is.gcount() == 6);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore_0xff.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore_0xff.pass.cpp
index f2f895d9ce6..acf90e56086 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore_0xff.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/ignore_0xff.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     int bad=-1;
     std::ostringstream os;
@@ -30,4 +30,6 @@ int main()
     is.ignore(ignoreLen);
     std::istringstream::pos_type b=is.tellg();
     assert((b-a)==ignoreLen);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/peek.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/peek.pass.cpp
index 99b2b69341b..17943463e90 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/peek.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/peek.pass.cpp
@@ -37,7 +37,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 1\n2345\n6");
@@ -65,4 +65,6 @@ int main()
         assert(!is.fail());
         assert(is.gcount() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/putback.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/putback.pass.cpp
index 2088e4d14cb..4ca3a8c0edb 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/putback.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/putback.pass.cpp
@@ -37,7 +37,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 123456789");
@@ -85,4 +85,6 @@ int main()
         assert(is.bad());
         assert(is.gcount() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/read.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/read.pass.cpp
index 962aa8c0386..9296e0bfb2e 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/read.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/read.pass.cpp
@@ -37,7 +37,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 123456789");
@@ -77,4 +77,6 @@ int main()
         assert( is.fail());
         assert(is.gcount() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp
index 5cfd028cc62..f99752cc1a5 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/readsome.pass.cpp
@@ -37,7 +37,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 1234567890");
@@ -81,4 +81,6 @@ int main()
         assert(std::wstring(s, 1) == L"0");
         assert(is.readsome(s, 5) == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg.pass.cpp
index b5e1955a7be..c16a6397863 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg.pass.cpp
@@ -44,7 +44,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 123456789");
@@ -71,4 +71,6 @@ int main()
         assert(is.good());
         assert(!is.eof());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg_off.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg_off.pass.cpp
index d7607b62e9d..93a7f1912d9 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg_off.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/seekg_off.pass.cpp
@@ -52,7 +52,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 123456789");
@@ -83,4 +83,6 @@ int main()
         assert(is.good());
         assert(!is.eof());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/sync.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/sync.pass.cpp
index 10bc991aa0f..43ddd811080 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/sync.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/sync.pass.cpp
@@ -46,7 +46,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 123456789");
@@ -60,4 +60,6 @@ int main()
         assert(is.sync() == 0);
         assert(sync_called == 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/tellg.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/tellg.pass.cpp
index 7f87cada9ac..918685b8693 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/tellg.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/tellg.pass.cpp
@@ -47,7 +47,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 123456789");
@@ -59,4 +59,6 @@ int main()
         std::wistream is(&sb);
         assert(is.tellg() == 5);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/unget.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/unget.pass.cpp
index c982f79cb96..ca00af4e3c3 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/unget.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream.unformatted/unget.pass.cpp
@@ -37,7 +37,7 @@ public:
     CharT* egptr() const {return base::egptr();}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb(" 123456789");
@@ -77,4 +77,6 @@ int main()
         assert(is.bad());
         assert(is.gcount() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/member_swap.pass.cpp
index 8e8b16600df..dbb2bb69e36 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/member_swap.pass.cpp
@@ -33,7 +33,7 @@ struct test_istream
     void swap(test_istream& s) {base::swap(s);}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb1;
@@ -81,4 +81,6 @@ int main()
         assert(is2.precision() == 6);
         assert(is2.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/move_assign.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/move_assign.pass.cpp
index cc418fd4f13..455edbf72ac 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/move_assign.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.assign/move_assign.pass.cpp
@@ -38,7 +38,7 @@ struct test_istream
 };
 
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb1;
@@ -86,4 +86,6 @@ int main()
         assert(is2.precision() == 6);
         assert(is2.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/copy.fail.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/copy.fail.cpp
index c26ad292ba8..017cc67a1d5 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/copy.fail.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/copy.fail.cpp
@@ -48,7 +48,9 @@ struct test_istream
 };
 
 
-int main()
+int main(int, char**)
 {
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/move.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/move.pass.cpp
index 7bf3d6619b0..4830d04d48c 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/move.pass.cpp
@@ -36,7 +36,7 @@ struct test_istream
         : base(std::move(s)) {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -70,4 +70,6 @@ int main()
         assert(is.precision() == 6);
         assert(is.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/streambuf.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/streambuf.pass.cpp
index 71008f7d096..339489dfb5e 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream.cons/streambuf.pass.cpp
@@ -23,7 +23,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -51,4 +51,6 @@ int main()
         assert(is.getloc().name() == "C");
         assert(is.gcount() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream_sentry/ctor.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream_sentry/ctor.pass.cpp
index 29fed345a54..fdebd66fb76 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream_sentry/ctor.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream/istream_sentry/ctor.pass.cpp
@@ -49,7 +49,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::istream is((testbuf<char>*)0);
@@ -124,4 +124,6 @@ int main()
         assert(sync_called == 0);
         assert(sb.gptr() == sb.eback());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/input.streams/istream/types.pass.cpp b/libcxx/test/std/input.output/iostream.format/input.streams/istream/types.pass.cpp
index 07e2f5558fe..a5362d94b8c 100644
--- a/libcxx/test/std/input.output/iostream.format/input.streams/istream/types.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/input.streams/istream/types.pass.cpp
@@ -23,7 +23,7 @@
 #include <istream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_ios<char>, std::basic_istream<char> >::value), "");
     static_assert((std::is_same<std::basic_istream<char>::char_type, char>::value), "");
@@ -31,4 +31,6 @@ int main()
     static_assert((std::is_same<std::basic_istream<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_istream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_istream<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostream.format/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostream.format/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/member_swap.pass.cpp
index f322a8145bd..433d78ead19 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/member_swap.pass.cpp
@@ -33,7 +33,7 @@ struct test_ostream
     void swap(test_ostream& s) {base::swap(s);}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb1;
@@ -81,4 +81,6 @@ int main()
         assert(os2.precision() == 6);
         assert(os2.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/move_assign.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/move_assign.pass.cpp
index a121cd8a5b9..4241b02a36d 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/move_assign.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.assign/move_assign.pass.cpp
@@ -38,7 +38,7 @@ struct test_ostream
 };
 
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb1;
@@ -86,4 +86,6 @@ int main()
         assert(os2.precision() == 6);
         assert(os2.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/move.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/move.pass.cpp
index 155889de717..811b7fa8566 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/move.pass.cpp
@@ -38,7 +38,7 @@ struct test_ostream
 };
 
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -68,4 +68,6 @@ int main()
         assert(os.precision() == 6);
         assert(os.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/streambuf.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/streambuf.pass.cpp
index ea4542be29e..78a3a53c74e 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.cons/streambuf.pass.cpp
@@ -23,7 +23,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -49,4 +49,6 @@ int main()
         assert(os.precision() == 6);
         assert(os.getloc().name() == "C");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.formatted.reqmts/tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.formatted.reqmts/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.formatted.reqmts/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.formatted.reqmts/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/bool.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/bool.pass.cpp
index e472c62660d..a0622b36567 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/bool.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/bool.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -87,4 +87,6 @@ int main()
         os << b;
         assert(sb.str() == "false");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/double.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/double.pass.cpp
index f18d9361ac4..2c83723cbfa 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/double.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/double.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "-10.5");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/float.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/float.pass.cpp
index 041195d0e36..851086abe42 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/float.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/float.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "-10.5");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/int.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/int.pass.cpp
index 4657c98f9c9..7dae78f9def 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/int.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/int.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fffffff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long.pass.cpp
index cf0184997b8..8f2ec631c03 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fffffff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_double.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_double.pass.cpp
index cedef612149..b0c9950bd7a 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_double.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_double.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "-10.5");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_long.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_long.pass.cpp
index 20b23b80bec..d87096f7213 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/long_long.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fffffffffffffff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minmax_showbase.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minmax_showbase.pass.cpp
index c101b3cfc99..6db1b55cca7 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minmax_showbase.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minmax_showbase.pass.cpp
@@ -45,7 +45,7 @@ static void test(std::ios_base::fmtflags fmt, const char *expected)
     assert(ss.str() == expected);
 }
 
-int main()
+int main(int, char**)
 {
     const std::ios_base::fmtflags o = std::ios_base::oct;
     const std::ios_base::fmtflags d = std::ios_base::dec;
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minus1.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minus1.pass.cpp
index 7d51a4ddd04..c2b188a15f9 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minus1.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/minus1.pass.cpp
@@ -58,7 +58,7 @@ void test_hex(const char *expected)
     assert(str == expected);
 }
 
-int main()
+int main(int, char**)
 {
 
     test_octal<uint16_t>(                "177777");
@@ -110,4 +110,6 @@ int main()
         test_hex<unsigned long long>("FFFFFFFFFFFFFFFF");
         test_hex<         long long>("FFFFFFFFFFFFFFFF");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/pointer.pass.cpp
index 837efd6f38a..f400f33544b 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/pointer.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -87,4 +87,6 @@ int main()
         os << n;
         assert(os.good());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/short.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/short.pass.cpp
index 8e022edad01..c45d5797b5e 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/short.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/short.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_int.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_int.pass.cpp
index 2d6b0be0274..c24381923d1 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_int.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_int.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long.pass.cpp
index 636c87146fe..03b63964302 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fffffff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long_long.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long_long.pass.cpp
index 44313251e10..3c12f148898 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long_long.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_long_long.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fffffffffffffff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_short.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_short.pass.cpp
index 16b33f3a94e..6cc4c71a094 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_short.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.arithmetic/unsigned_short.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -79,4 +79,6 @@ int main()
         os << n;
         assert(sb.str() == "fff6");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT.pass.cpp
index cb7f0d62f47..127c0c7dc5b 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::wostream os((std::wstreambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == L"a    ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT_pointer.pass.cpp
index a07edba5d9f..85edde06d4f 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/CharT_pointer.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::wostream os((std::wstreambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == L"123  ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char.pass.cpp
index 6e926d10fb0..5532a68650b 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == "a    ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_pointer.pass.cpp
index 23874768fd0..f6e2445faeb 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_pointer.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == "123  ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide.pass.cpp
index f5647e1a924..f12478e5384 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::wostream os((std::wstreambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == L"a    ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide_pointer.pass.cpp
index ff4e85eb90f..1b11d8550ae 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/char_to_wide_pointer.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::wostream os((std::wstreambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == L"123  ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char.pass.cpp
index ab3e9b580b8..26f295ec2d0 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == "a    ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char_pointer.pass.cpp
index 36b9586b812..83143521bc5 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/signed_char_pointer.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == "123  ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char.pass.cpp
index 95609a2642b..e45281f866f 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == "a    ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char_pointer.pass.cpp
index ef7e6166e9d..55b429b2dc4 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters.character/unsigned_char_pointer.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -84,4 +84,6 @@ int main()
         assert(sb.str() == "123  ");
         assert(os.width() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/basic_ios.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/basic_ios.pass.cpp
index 1d205625081..921311f99ce 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/basic_ios.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/basic_ios.pass.cpp
@@ -57,7 +57,7 @@ f(std::basic_ios<CharT>& os)
     return os;
 }
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -66,4 +66,6 @@ int main()
         os << f;
         assert( (os.flags() & std::ios_base::uppercase));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ios_base.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ios_base.pass.cpp
index 763be3a8382..b10330b7c69 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ios_base.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ios_base.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -57,4 +57,6 @@ int main()
         os << std::uppercase;
         assert( (os.flags() & std::ios_base::uppercase));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ostream.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ostream.pass.cpp
index ab39c28aac6..e57e5412c39 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ostream.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/ostream.pass.cpp
@@ -57,7 +57,7 @@ f(std::basic_ostream<CharT>& os)
     return os;
 }
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -65,4 +65,6 @@ int main()
         os << f;
         assert(sb.str() == "testing...");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/streambuf.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/streambuf.pass.cpp
index 5668185b0cf..d2935ca734a 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.formatted/ostream.inserters/streambuf.pass.cpp
@@ -55,7 +55,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -65,4 +65,6 @@ int main()
         os << &sb2;
         assert(sb.str() == "testing...");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/endl.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/endl.pass.cpp
index c6a7d92180c..03cd411294b 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/endl.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/endl.pass.cpp
@@ -58,7 +58,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -76,4 +76,6 @@ int main()
         assert(sync_called == 2);
         assert(os.good());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/ends.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/ends.pass.cpp
index 20703864bbe..5f18aecf907 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/ends.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/ends.pass.cpp
@@ -49,7 +49,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -67,4 +67,6 @@ int main()
         assert(sb.str().back() == 0);
         assert(os.good());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/flush.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/flush.pass.cpp
index 8ad82cb3a30..666a92532f8 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/flush.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.manip/flush.pass.cpp
@@ -38,7 +38,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -54,4 +54,6 @@ int main()
         assert(sync_called == 2);
         assert(os.good());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.rvalue/CharT_pointer.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.rvalue/CharT_pointer.pass.cpp
index 7b7890abddd..724593f1acd 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.rvalue/CharT_pointer.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.rvalue/CharT_pointer.pass.cpp
@@ -54,7 +54,7 @@ protected:
 };
 
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -66,4 +66,6 @@ int main()
         std::wostream(&sb) << L"123";
         assert(sb.str() == L"123");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp
index f48ed92b8b6..7be006f1060 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp.pass.cpp
@@ -36,7 +36,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         seekpos_called = 0;
@@ -64,4 +64,6 @@ int main()
         assert(seekpos_called == 1);
         assert(os.rdstate() == std::ios_base::eofbit);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp
index 130528046e3..dc8e5ed5cd3 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/seekp2.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         seekoff_called = 0;
@@ -66,4 +66,6 @@ int main()
         assert(seekoff_called == 1);
         assert(os.rdstate() == std::ios_base::eofbit);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/tellp.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/tellp.pass.cpp
index a93032b20be..d9361e83978 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/tellp.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.seeks/tellp.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -50,4 +50,6 @@ int main()
         assert(os.tellp() == 10);
         assert(seekoff_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/flush.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/flush.pass.cpp
index f07af7471bf..15a3b59ea0a 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/flush.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/flush.pass.cpp
@@ -38,7 +38,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -50,4 +50,6 @@ int main()
         assert(os.bad());
         assert(sync_called == 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/put.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/put.pass.cpp
index 4dc25175130..79f7d9f9fb8 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/put.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/put.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::wostream os((std::wstreambuf*)0);
@@ -72,4 +72,6 @@ int main()
         assert(sb.str() == "a");
         assert(os.good());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/write.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/write.pass.cpp
index 4b804a501ff..9ebfdf54b50 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/write.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream.unformatted/write.pass.cpp
@@ -48,7 +48,7 @@ protected:
         }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::wostream os((std::wstreambuf*)0);
@@ -72,4 +72,6 @@ int main()
         assert(sb.str() == s);
         assert(os.good());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream/types.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream/types.pass.cpp
index dbdb52ee749..e0e9cddde41 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream/types.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream/types.pass.cpp
@@ -23,7 +23,7 @@
 #include <ostream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_ios<char>, std::basic_ostream<char> >::value), "");
     static_assert((std::is_same<std::basic_ostream<char>::char_type, char>::value), "");
@@ -31,4 +31,6 @@ int main()
     static_assert((std::is_same<std::basic_ostream<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_ostream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_ostream<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/construct.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/construct.pass.cpp
index f7d78537eb7..c21776a9aa4 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/construct.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/construct.pass.cpp
@@ -33,7 +33,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -57,4 +57,6 @@ int main()
         assert(bool(s));
         assert(sync_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/destruct.pass.cpp b/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/destruct.pass.cpp
index ab67442d7b6..66ed0acba26 100644
--- a/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/destruct.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/output.streams/ostream_sentry/destruct.pass.cpp
@@ -35,7 +35,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::ostream os((std::streambuf*)0);
@@ -75,4 +75,6 @@ int main()
         assert(sync_called == 1);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted.pass.cpp b/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted.pass.cpp
index c39c0808716..1e54e5657ef 100644
--- a/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted.pass.cpp
@@ -123,7 +123,7 @@ void test_padding () {
 }
 
 
-int main()
+int main(int, char**)
 {
     both_ways ( "" );   // This is a compilation check
 
@@ -173,8 +173,12 @@ int main()
     assert ( unquote (  "" ) ==  "" ); // nothing there
     assert ( unquote ( L"" ) == L"" ); // nothing there
     test_padding ();
-    }
+    
+    return 0;
+}
 
 #else
-int main() {}
+int main(int, char**) {
+  return 0;
+}
 #endif
diff --git a/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_char.fail.cpp b/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_char.fail.cpp
index d7b33cdf230..4b343013e25 100644
--- a/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_char.fail.cpp
+++ b/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_char.fail.cpp
@@ -30,7 +30,7 @@ void round_trip ( const char *p ) {
 
 
 
-int main()
+int main(int, char**)
 {
     round_trip ( "Hi Mom" );
 }
diff --git a/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_traits.fail.cpp b/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_traits.fail.cpp
index 257826b7dbf..b19eea376d8 100644
--- a/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_traits.fail.cpp
+++ b/libcxx/test/std/input.output/iostream.format/quoted.manip/quoted_traits.fail.cpp
@@ -36,7 +36,7 @@ void round_trip ( const char *p ) {
 
 
 
-int main()
+int main(int, char**)
 {
     round_trip ( "Hi Mom" );
 }
diff --git a/libcxx/test/std/input.output/iostream.format/std.manip/resetiosflags.pass.cpp b/libcxx/test/std/input.output/iostream.format/std.manip/resetiosflags.pass.cpp
index 82ef40c9a12..637aa4ee317 100644
--- a/libcxx/test/std/input.output/iostream.format/std.manip/resetiosflags.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/std.manip/resetiosflags.pass.cpp
@@ -22,7 +22,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -52,4 +52,6 @@ int main()
         os << std::resetiosflags(std::ios_base::skipws);
         assert(!(os.flags() & std::ios_base::skipws));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/std.manip/setbase.pass.cpp b/libcxx/test/std/input.output/iostream.format/std.manip/setbase.pass.cpp
index 83d4960c420..580ae4d24c3 100644
--- a/libcxx/test/std/input.output/iostream.format/std.manip/setbase.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/std.manip/setbase.pass.cpp
@@ -22,7 +22,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -72,4 +72,6 @@ int main()
         os << std::setbase(15);
         assert((os.flags() & std::ios_base::basefield) == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/std.manip/setfill.pass.cpp b/libcxx/test/std/input.output/iostream.format/std.manip/setfill.pass.cpp
index cc548b37ddd..4398ff61301 100644
--- a/libcxx/test/std/input.output/iostream.format/std.manip/setfill.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/std.manip/setfill.pass.cpp
@@ -21,7 +21,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -35,4 +35,6 @@ int main()
         os << std::setfill(L'*');
         assert(os.fill() == L'*');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/std.manip/setiosflags.pass.cpp b/libcxx/test/std/input.output/iostream.format/std.manip/setiosflags.pass.cpp
index f4bf9e7f4fd..ccf605ad7ad 100644
--- a/libcxx/test/std/input.output/iostream.format/std.manip/setiosflags.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/std.manip/setiosflags.pass.cpp
@@ -22,7 +22,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -52,4 +52,6 @@ int main()
         os << std::setiosflags(std::ios_base::oct);
         assert(os.flags() & std::ios_base::oct);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/std.manip/setprecision.pass.cpp b/libcxx/test/std/input.output/iostream.format/std.manip/setprecision.pass.cpp
index eef401c63e5..e570faf7cb7 100644
--- a/libcxx/test/std/input.output/iostream.format/std.manip/setprecision.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/std.manip/setprecision.pass.cpp
@@ -22,7 +22,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -48,4 +48,6 @@ int main()
         os << std::setprecision(10);
         assert(os.precision() == 10);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.format/std.manip/setw.pass.cpp b/libcxx/test/std/input.output/iostream.format/std.manip/setw.pass.cpp
index cd5e3f2b3e9..44aa41e5746 100644
--- a/libcxx/test/std/input.output/iostream.format/std.manip/setw.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.format/std.manip/setw.pass.cpp
@@ -22,7 +22,7 @@ struct testbuf
     testbuf() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb;
@@ -48,4 +48,6 @@ int main()
         os << std::setw(10);
         assert(os.width() == 10);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.forward/iosfwd.pass.cpp b/libcxx/test/std/input.output/iostream.forward/iosfwd.pass.cpp
index 1caadd1c099..5c60dcca286 100644
--- a/libcxx/test/std/input.output/iostream.forward/iosfwd.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.forward/iosfwd.pass.cpp
@@ -17,7 +17,7 @@ template <class Ptr> void test()
     ((void)p); // Prevent unused warning
 }
 
-int main()
+int main(int, char**)
 {
     test<std::char_traits<char>*          >();
     test<std::char_traits<wchar_t>*       >();
@@ -119,4 +119,6 @@ int main()
     test<std::fpos<std::mbstate_t>*>();
     test<std::streampos*           >();
     test<std::wstreampos*          >();
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cerr.pass.cpp b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cerr.pass.cpp
index 1c046bcf447..ef3cbf676aa 100644
--- a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cerr.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cerr.pass.cpp
@@ -13,7 +13,7 @@
 #include <iostream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::cerr << "Hello World!\n";
@@ -25,4 +25,6 @@ int main()
 #endif
     assert(std::cerr.flags() & std::ios_base::unitbuf);
 #endif  // 0
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cin.pass.cpp b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cin.pass.cpp
index cce1f3eaf62..d28255043b6 100644
--- a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cin.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cin.pass.cpp
@@ -15,7 +15,7 @@
 #include <iostream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::cout << "Hello World!\n";
@@ -30,4 +30,6 @@ int main()
     assert(std::cin.tie() == &std::cout);
 #endif
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/clog.pass.cpp b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/clog.pass.cpp
index 49fffca4286..97e67fddf81 100644
--- a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/clog.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/clog.pass.cpp
@@ -12,11 +12,13 @@
 
 #include <iostream>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::clog << "Hello World!\n";
 #else
     (void)std::clog;
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cout.pass.cpp b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cout.pass.cpp
index d470956e284..44ae0857792 100644
--- a/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cout.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/narrow.stream.objects/cout.pass.cpp
@@ -14,7 +14,7 @@
 
 #include <iostream>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::cout << "Hello World!\n";
@@ -25,4 +25,6 @@ int main()
 #else  // 0
     (void)std::cout;
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcerr.pass.cpp b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcerr.pass.cpp
index 516f3b8c994..0af3f5ee7e5 100644
--- a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcerr.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcerr.pass.cpp
@@ -13,7 +13,7 @@
 #include <iostream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::wcerr << L"Hello World!\n";
@@ -25,4 +25,6 @@ int main()
 #endif
     assert(std::wcerr.flags() & std::ios_base::unitbuf);
 #endif  // 0
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcin.pass.cpp b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcin.pass.cpp
index 862f2203456..68c1528602b 100644
--- a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcin.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcin.pass.cpp
@@ -15,7 +15,7 @@
 #include <iostream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::wcout << L"Hello World!\n";
@@ -30,4 +30,6 @@ int main()
     assert(std::wcin.tie() == &std::wcout);
 #endif
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wclog.pass.cpp b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wclog.pass.cpp
index a6883b25704..ad7e35b5151 100644
--- a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wclog.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wclog.pass.cpp
@@ -12,11 +12,13 @@
 
 #include <iostream>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::wclog << L"Hello World!\n";
 #else
     (void)std::wclog;
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcout.pass.cpp b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcout.pass.cpp
index ec5bb50ecb0..5703c61639d 100644
--- a/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcout.pass.cpp
+++ b/libcxx/test/std/input.output/iostream.objects/wide.stream.objects/wcout.pass.cpp
@@ -14,11 +14,13 @@
 
 #include <iostream>
 
-int main()
+int main(int, char**)
 {
 #if 0
     std::wcout << L"Hello World!\n";
 #else
     (void)std::wcout;
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.members/state.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.members/state.pass.cpp
index 9c4d74dcd09..3938d79804c 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.members/state.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.members/state.pass.cpp
@@ -15,9 +15,11 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::fpos<int> f;
     f.state(3);
     assert(f.state() == 3);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/addition.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/addition.pass.cpp
index 1b58566088c..30bdabc368c 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/addition.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/addition.pass.cpp
@@ -15,7 +15,7 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::fpos<std::mbstate_t> P;
     P p(5);
@@ -24,4 +24,6 @@ int main()
     assert(q == P(11));
     p += o;
     assert(p == q);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/ctor_int.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/ctor_int.pass.cpp
index ff30e81afbc..e27c9068784 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/ctor_int.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/ctor_int.pass.cpp
@@ -15,9 +15,11 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::fpos<std::mbstate_t> P;
     P p(5);
     assert(p == P(5));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/difference.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/difference.pass.cpp
index 405c98899fc..114e382a71f 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/difference.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/difference.pass.cpp
@@ -15,11 +15,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::fpos<std::mbstate_t> P;
     P p(11);
     P q(6);
     std::streamoff o = p - q;
     assert(o == 5);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/eq_int.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/eq_int.pass.cpp
index 20ffe33c413..1b1a5f33d1c 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/eq_int.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/eq_int.pass.cpp
@@ -15,11 +15,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::fpos<std::mbstate_t> P;
     P p(5);
     P q(6);
     assert(p == p);
     assert(p != q);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/offset.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/offset.pass.cpp
index 108cffdf90f..a8e763f7245 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/offset.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/offset.pass.cpp
@@ -15,10 +15,12 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::fpos<std::mbstate_t> P;
     P p(std::streamoff(7));
     std::streamoff offset(p);
     assert(offset == 7);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/streamsize.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/streamsize.pass.cpp
index e6cb51ae174..9d9cd79024e 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/streamsize.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/streamsize.pass.cpp
@@ -13,11 +13,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::streamoff o(5);
     std::streamsize sz(o);
     assert(sz == 5);
     std::streamoff o2(sz);
     assert(o == o2);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/subtraction.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/subtraction.pass.cpp
index 9991be4f953..b38378b7e8c 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/subtraction.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/fpos.operations/subtraction.pass.cpp
@@ -15,7 +15,7 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     typedef std::fpos<std::mbstate_t> P;
     P p(11);
@@ -24,4 +24,6 @@ int main()
     assert(q == P(5));
     p -= o;
     assert(p == q);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/fpos/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostreams.base/fpos/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.base/fpos/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/fpos/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags.pass.cpp
index 1a958b615b9..da147bd82f8 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags.pass.cpp
@@ -25,8 +25,10 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     const test t;
     assert(t.flags() == (test::skipws | test::dec));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags_fmtflags.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags_fmtflags.pass.cpp
index 0f49701fbf2..ed39a54245a 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags_fmtflags.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/flags_fmtflags.pass.cpp
@@ -25,11 +25,13 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.flags() == (test::skipws | test::dec));
     test::fmtflags f = t.flags(test::hex | test::right);
     assert(f == (test::skipws | test::dec));
     assert(t.flags() == (test::hex | test::right));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision.pass.cpp
index d22ca2647b5..f6387c828f2 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision.pass.cpp
@@ -25,8 +25,10 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     const test t;
     assert(t.precision() == 6);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision_streamsize.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision_streamsize.pass.cpp
index ab38ab3d5e8..475ddc47f8a 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision_streamsize.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/precision_streamsize.pass.cpp
@@ -25,11 +25,13 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.precision() == 6);
     std::streamsize p = t.precision(10);
     assert(p == 6);
     assert(t.precision() == 10);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags.pass.cpp
index da742974dab..d8ca9cc8239 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags.pass.cpp
@@ -25,11 +25,13 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.flags() == (test::skipws | test::dec));
     test::fmtflags f = t.setf(test::hex | test::right);
     assert(f == (test::skipws | test::dec));
     assert(t.flags() == (test::skipws | test::dec | test::hex | test::right));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags_mask.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags_mask.pass.cpp
index 00ce003dada..6793ced7fe0 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags_mask.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/setf_fmtflags_mask.pass.cpp
@@ -25,11 +25,13 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.flags() == (test::skipws | test::dec));
     test::fmtflags f = t.setf(test::hex | test::right, test::dec | test::right);
     assert(f == (test::skipws | test::dec));
     assert(t.flags() == (test::skipws | test::right));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/unsetf_mask.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/unsetf_mask.pass.cpp
index 49a55cb4023..f20acff1347 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/unsetf_mask.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/unsetf_mask.pass.cpp
@@ -25,10 +25,12 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.flags() == (test::skipws | test::dec));
     t.unsetf(test::dec | test::right);
     assert(t.flags() == test::skipws);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width.pass.cpp
index d812aa291f1..fc2601a4567 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width.pass.cpp
@@ -25,8 +25,10 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     const test t;
     assert(t.width() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width_streamsize.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width_streamsize.pass.cpp
index 7c906094804..3b389e5fd22 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width_streamsize.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/fmtflags.state/width_streamsize.pass.cpp
@@ -25,11 +25,13 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.width() == 0);
     std::streamsize w = t.width(4);
     assert(w == 0);
     assert(t.width() == 4);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.callback/register_callback.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.callback/register_callback.pass.cpp
index 3de42eabc4a..316d23a528b 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.callback/register_callback.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.callback/register_callback.pass.cpp
@@ -43,7 +43,7 @@ void f1(std::ios_base::event ev, std::ios_base& stream, int index)
     }
 }
 
-int main()
+int main(int, char**)
 {
     test t;
     std::ios_base& b = t;
@@ -52,4 +52,6 @@ int main()
     b.register_callback(f1, 4);
     std::locale l = b.imbue(std::locale(LOCALE_en_US_UTF_8));
     assert(f1_called == 3);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.cons/dtor.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.cons/dtor.pass.cpp
index 12434f5a219..7c78ea5667d 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.cons/dtor.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.cons/dtor.pass.cpp
@@ -70,7 +70,7 @@ void f3(std::ios_base::event ev, std::ios_base& stream, int index)
     }
 }
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -82,4 +82,6 @@ int main()
     assert(f1_called);
     assert(f2_called);
     assert(f3_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/getloc.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/getloc.pass.cpp
index 821a1f51461..06b8d83c79e 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/getloc.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/getloc.pass.cpp
@@ -26,8 +26,10 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     const test t;
     assert(t.getloc().name() == std::string("C"));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/imbue.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/imbue.pass.cpp
index 0fa77cb7ac2..ad8898a170f 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/imbue.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.locales/imbue.pass.cpp
@@ -74,7 +74,7 @@ void f3(std::ios_base::event ev, std::ios_base& stream, int index)
     }
 }
 
-int main()
+int main(int, char**)
 {
     test t;
     std::ios_base& b = t;
@@ -87,4 +87,6 @@ int main()
     assert(f1_called);
     assert(f2_called);
     assert(f3_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/iword.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/iword.pass.cpp
index 467b885cebe..84eb18370c3 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/iword.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/iword.pass.cpp
@@ -29,7 +29,7 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     std::ios_base& b = t;
@@ -41,4 +41,6 @@ int main()
         for (int j = 0; j <= i; ++j)
             assert(b.iword(j) == j);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/pword.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/pword.pass.cpp
index 65aca332ac2..c4594615daa 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/pword.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/pword.pass.cpp
@@ -30,7 +30,7 @@ public:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     std::ios_base& b = t;
@@ -42,4 +42,6 @@ int main()
         for (std::intptr_t j = 0; j <= i; ++j)
             assert(b.pword(j) == (void*)j);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/xalloc.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/xalloc.pass.cpp
index dd95b26819f..2fcaddd6d54 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/xalloc.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.base.storage/xalloc.pass.cpp
@@ -15,11 +15,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::ios_base::xalloc() == 0);
     assert(std::ios_base::xalloc() == 1);
     assert(std::ios_base::xalloc() == 2);
     assert(std::ios_base::xalloc() == 3);
     assert(std::ios_base::xalloc() == 4);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.members.static/sync_with_stdio.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.members.static/sync_with_stdio.pass.cpp
index 8937f2585bf..cd219971e54 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.members.static/sync_with_stdio.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.members.static/sync_with_stdio.pass.cpp
@@ -13,7 +13,7 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert( std::ios_base::sync_with_stdio(false));
     assert(!std::ios_base::sync_with_stdio(false));
@@ -23,4 +23,6 @@ int main()
     assert( std::ios_base::sync_with_stdio(false));
     assert(!std::ios_base::sync_with_stdio());
     assert( std::ios_base::sync_with_stdio());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_Init/tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_Init/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_Init/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_Init/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_char_pointer_error_code.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_char_pointer_error_code.pass.cpp
index 0fc16259974..382aeda4f11 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_char_pointer_error_code.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_char_pointer_error_code.pass.cpp
@@ -17,7 +17,7 @@
 #include <system_error>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::string what_arg("io test message");
@@ -37,4 +37,6 @@ int main()
         assert(what_message.find(std::iostream_category().message(static_cast<int>
             (std::io_errc::stream))) != std::string::npos);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_string_error_code.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_string_error_code.pass.cpp
index cc607d9458d..610e6ad1527 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_string_error_code.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_failure/ctor_string_error_code.pass.cpp
@@ -17,7 +17,7 @@
 #include <system_error>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     // LWG2462 std::ios_base::failure is overspecified
     static_assert((std::is_base_of<std::system_error, std::ios_base::failure>::value), "");
@@ -40,4 +40,6 @@ int main()
         assert(what_message.find(std::iostream_category().message(static_cast<int>
             (std::io_errc::stream))) != std::string::npos);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_fmtflags/fmtflags.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_fmtflags/fmtflags.pass.cpp
index 6a51484f3f7..2eed477b0dd 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_fmtflags/fmtflags.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_fmtflags/fmtflags.pass.cpp
@@ -32,7 +32,7 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::ios_base::boolalpha);
     assert(std::ios_base::dec);
@@ -77,4 +77,6 @@ int main()
                                       | std::ios_base::hex));
     assert(std::ios_base::floatfield == (std::ios_base::scientific
                                        | std::ios_base::fixed));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_iostate/iostate.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_iostate/iostate.pass.cpp
index 64123e5d186..7e982f25f5f 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_iostate/iostate.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_iostate/iostate.pass.cpp
@@ -18,7 +18,7 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::ios_base::badbit);
     assert(std::ios_base::eofbit);
@@ -32,4 +32,6 @@ int main()
     );
 
     assert(std::ios_base::goodbit == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_openmode/openmode.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_openmode/openmode.pass.cpp
index 88c292955d3..ab21f96b7fc 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_openmode/openmode.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_openmode/openmode.pass.cpp
@@ -20,7 +20,7 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::ios_base::app);
     assert(std::ios_base::ate);
@@ -38,4 +38,6 @@ int main()
         & std::ios_base::out
         & std::ios_base::trunc) == 0
     );
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_seekdir/seekdir.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_seekdir/seekdir.pass.cpp
index 3d0c80974fe..dfa955c7f55 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_seekdir/seekdir.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/ios_seekdir/seekdir.pass.cpp
@@ -17,9 +17,11 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::ios_base::beg != std::ios_base::cur);
     assert(std::ios_base::beg != std::ios_base::end);
     assert(std::ios_base::cur != std::ios_base::end);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/ios.types/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios.base/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios.base/nothing_to_do.pass.cpp
index 8e23732f09f..c4eff25bcb1 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios.base/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios.base/nothing_to_do.pass.cpp
@@ -10,6 +10,8 @@
 
 #include <ios>
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.cons/ctor_streambuf.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.cons/ctor_streambuf.pass.cpp
index 1bd33e96170..01c0d4679bc 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.cons/ctor_streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.cons/ctor_streambuf.pass.cpp
@@ -16,7 +16,7 @@
 #include <streambuf>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::streambuf* sb = 0;
@@ -44,4 +44,6 @@ int main()
         assert(ios.fill() == ' ');
         assert(ios.getloc() == std::locale());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/copyfmt.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/copyfmt.pass.cpp
index 08d00c1c0a9..949c87e0b83 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/copyfmt.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/copyfmt.pass.cpp
@@ -110,7 +110,7 @@ void g3(std::ios_base::event ev, std::ios_base& stream, int index)
     }
 }
 
-int main()
+int main(int, char**)
 {
     testbuf sb1;
     std::ios ios1(&sb1);
@@ -190,4 +190,6 @@ int main()
     assert(ios1.tie() == (std::ostream*)2);
     assert(ios1.fill() == '2');
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill.pass.cpp
index b5cc96c3384..f45c6c8b25c 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill.pass.cpp
@@ -15,8 +15,10 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     const std::ios ios(0);
     assert(ios.fill() == ' ');
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill_char_type.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill_char_type.pass.cpp
index b1c56ed539d..1c42a03fb31 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill_char_type.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/fill_char_type.pass.cpp
@@ -15,11 +15,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::ios ios(0);
     assert(ios.fill() == ' ');
     char c = ios.fill('*');
     assert(c == ' ');
     assert(ios.fill() == '*');
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/imbue.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/imbue.pass.cpp
index 3874372902f..ed0df788daa 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/imbue.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/imbue.pass.cpp
@@ -68,7 +68,7 @@ void f3(std::ios_base::event ev, std::ios_base& stream, int index)
     }
 }
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -99,4 +99,6 @@ int main()
         assert(f2_called);
         assert(f3_called);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/move.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/move.pass.cpp
index 4c60756746e..5f99f3db0ae 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/move.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/move.pass.cpp
@@ -77,7 +77,7 @@ void g3(std::ios_base::event ev, std::ios_base&, int index)
     }
 }
 
-int main()
+int main(int, char**)
 {
     testios ios1;
     testbuf sb2;
@@ -136,4 +136,6 @@ int main()
 
     assert(ios2.rdbuf() == &sb2);
     assert(ios2.tie() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/narrow.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/narrow.pass.cpp
index b1ffc1e96d6..afab4ec5def 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/narrow.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/narrow.pass.cpp
@@ -15,9 +15,11 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     const std::wios ios(0);
     assert(ios.narrow(L'c', '*') == 'c');
     assert(ios.narrow(L'\u203C', '*') == '*');
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf.pass.cpp
index bc5871f924d..f104cada627 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf.pass.cpp
@@ -16,7 +16,7 @@
 #include <streambuf>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         const std::ios ios(0);
@@ -27,4 +27,6 @@ int main()
         const std::ios ios(sb);
         assert(ios.rdbuf() == sb);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf_streambuf.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf_streambuf.pass.cpp
index c1aa1aaf3de..5c4e24a82eb 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf_streambuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/rdbuf_streambuf.pass.cpp
@@ -16,7 +16,7 @@
 #include <streambuf>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::ios ios(0);
     assert(ios.rdbuf() == 0);
@@ -30,4 +30,6 @@ int main()
     assert(sb2 == (std::streambuf*)1);
     assert(ios.rdbuf() == 0);
     assert(ios.bad());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/set_rdbuf.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/set_rdbuf.pass.cpp
index 65f66cb4b63..04b1b9ff6b0 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/set_rdbuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/set_rdbuf.pass.cpp
@@ -30,7 +30,7 @@ struct testios
     void set_rdbuf(std::streambuf* x) {std::ios::set_rdbuf(x);}
 };
 
-int main()
+int main(int, char**)
 {
     testbuf sb1;
     testbuf sb2;
@@ -60,4 +60,6 @@ int main()
 #endif
     ios.set_rdbuf(0);
     assert(ios.rdbuf() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/swap.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/swap.pass.cpp
index 559768b945b..40e95bae704 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/swap.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/swap.pass.cpp
@@ -70,7 +70,7 @@ void g3(std::ios_base::event, std::ios_base&, int index)
     g3_called = true;
 }
 
-int main()
+int main(int, char**)
 {
     testbuf sb1;
     testios ios1(&sb1);
@@ -164,4 +164,6 @@ int main()
     ios2.imbue(std::locale("C"));
     assert(f1_called);
     assert(f2_called);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie.pass.cpp
index 6ea816d7d1b..c0d7ac17332 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie.pass.cpp
@@ -15,8 +15,10 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     const std::basic_ios<char> ios(0);
     assert(ios.tie() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie_ostream.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie_ostream.pass.cpp
index d2bb41c4e28..4ce5966add8 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie_ostream.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/tie_ostream.pass.cpp
@@ -15,11 +15,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::ios ios(0);
     std::ostream* os = (std::ostream*)1;
     std::ostream* r = ios.tie(os);
     assert(r == 0);
     assert(ios.tie() == os);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/widen.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/widen.pass.cpp
index a1585cd545e..0ae5637184c 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/widen.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/basic.ios.members/widen.pass.cpp
@@ -15,8 +15,10 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     const std::ios ios(0);
     assert(ios.widen('c') == 'c');
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bad.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bad.pass.cpp
index 158c953a401..2308cfa929f 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bad.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bad.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -37,4 +37,6 @@ int main()
         ios.setstate(std::ios::badbit);
         assert(ios.bad());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bool.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bool.pass.cpp
index 126431ce20d..24fcbff3926 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bool.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/bool.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     std::ios ios(0);
     assert(static_cast<bool>(ios) == !ios.fail());
@@ -30,4 +30,6 @@ int main()
 #if TEST_STD_VER >= 11
     static_assert((!std::is_convertible<std::ios, bool>::value), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/clear.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/clear.pass.cpp
index 7938a84cfe4..6fc38fde9ba 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/clear.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/clear.pass.cpp
@@ -20,7 +20,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -66,4 +66,6 @@ int main()
         ios.clear(std::ios::eofbit);
         assert(ios.rdstate() == std::ios::eofbit);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/eof.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/eof.pass.cpp
index bf65663427f..bf1d0246d4d 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/eof.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/eof.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -33,4 +33,6 @@ int main()
         ios.setstate(std::ios::eofbit);
         assert(ios.eof());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions.pass.cpp
index 9a6b3233f7f..4632e004333 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         const std::ios ios(0);
@@ -29,4 +29,6 @@ int main()
         const std::ios ios(&sb);
         assert(ios.exceptions() == std::ios::goodbit);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions_iostate.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions_iostate.pass.cpp
index 1d56d475a9e..b8b6577b243 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions_iostate.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/exceptions_iostate.pass.cpp
@@ -20,7 +20,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -48,4 +48,6 @@ int main()
         ios.exceptions(std::ios::badbit);
         assert(ios.exceptions() == std::ios::badbit);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/fail.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/fail.pass.cpp
index a475c3589ab..3ae215e45f4 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/fail.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/fail.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -37,4 +37,6 @@ int main()
         ios.setstate(std::ios::failbit);
         assert(ios.fail());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/good.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/good.pass.cpp
index e4f28bfe325..19c05edce67 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/good.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/good.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -31,4 +31,6 @@ int main()
         ios.setstate(std::ios::eofbit);
         assert(!ios.good());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/not.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/not.pass.cpp
index 151c2244e80..20ddb35dcca 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/not.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/not.pass.cpp
@@ -15,10 +15,12 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::ios ios(0);
     assert(!ios == ios.fail());
     ios.setstate(std::ios::failbit);
     assert(!ios == ios.fail());
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/rdstate.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/rdstate.pass.cpp
index dde113a918c..37886ac83e2 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/rdstate.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/rdstate.pass.cpp
@@ -15,10 +15,12 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::ios ios(0);
     assert(ios.rdstate() == std::ios::badbit);
     ios.setstate(std::ios::failbit);
     assert(ios.rdstate() == (std::ios::failbit | std::ios::badbit));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/setstate.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/setstate.pass.cpp
index 830dd448ef1..ea954bee05e 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/setstate.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/iostate.flags/setstate.pass.cpp
@@ -20,7 +20,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     {
         std::ios ios(0);
@@ -65,4 +65,6 @@ int main()
         ios.setstate(std::ios::failbit);
         assert(ios.rdstate() == (std::ios::eofbit | std::ios::failbit));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/ios/types.pass.cpp b/libcxx/test/std/input.output/iostreams.base/ios/types.pass.cpp
index 58165fc4444..b4a4d7c57d8 100644
--- a/libcxx/test/std/input.output/iostreams.base/ios/types.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/ios/types.pass.cpp
@@ -21,7 +21,7 @@
 #include <ios>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::ios_base, std::basic_ios<char> >::value), "");
     static_assert((std::is_same<std::basic_ios<char>::char_type, char>::value), "");
@@ -29,4 +29,6 @@ int main()
     static_assert((std::is_same<std::basic_ios<char>::int_type, std::char_traits<char>::int_type>::value), "");
     static_assert((std::is_same<std::basic_ios<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_ios<char>::off_type, std::char_traits<char>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/is_error_code_enum_io_errc.pass.cpp b/libcxx/test/std/input.output/iostreams.base/is_error_code_enum_io_errc.pass.cpp
index c087871ea84..76eb83148b3 100644
--- a/libcxx/test/std/input.output/iostreams.base/is_error_code_enum_io_errc.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/is_error_code_enum_io_errc.pass.cpp
@@ -15,10 +15,12 @@
 #include <ios>
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     static_assert(std::is_error_code_enum  <std::io_errc>::value, "");
 #if TEST_STD_VER > 14
     static_assert(std::is_error_code_enum_v<std::io_errc>, "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/internal.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/internal.pass.cpp
index a214813984e..fba2e71ca7d 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/internal.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/internal.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::internal(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::internal);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/left.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/left.pass.cpp
index 1073e2522be..f89d6b9e78f 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/left.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/left.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::left(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::left);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/right.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/right.pass.cpp
index c391ab8c500..399d3ba51dc 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/right.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/adjustfield.manip/right.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::right(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::right);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/dec.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/dec.pass.cpp
index 64351b6b192..98740cdc026 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/dec.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/dec.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::dec(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::dec);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/hex.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/hex.pass.cpp
index cab0bc25834..39addcdcf24 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/hex.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/hex.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::hex(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::hex);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/oct.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/oct.pass.cpp
index a4073646c4e..92b2d4ee7ef 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/oct.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/basefield.manip/oct.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::oct(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::oct);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/iostream_category.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/iostream_category.pass.cpp
index 0517481b899..e017c632a4d 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/iostream_category.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/iostream_category.pass.cpp
@@ -14,9 +14,11 @@
 #include <cassert>
 #include <string>
 
-int main()
+int main(int, char**)
 {
     const std::error_category& e_cat1 = std::iostream_category();
     std::string m1 = e_cat1.name();
     assert(m1 == "iostream");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_code.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_code.pass.cpp
index 745349d14cb..060b6284cac 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_code.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_code.pass.cpp
@@ -13,11 +13,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::error_code ec = make_error_code(std::io_errc::stream);
         assert(ec.value() == static_cast<int>(std::io_errc::stream));
         assert(ec.category() == std::iostream_category());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_condition.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_condition.pass.cpp
index ce9f9f02052..3970708bfa0 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_condition.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/error.reporting/make_error_condition.pass.cpp
@@ -13,11 +13,13 @@
 #include <ios>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         const std::error_condition ec1 = std::make_error_condition(std::io_errc::stream);
         assert(ec1.value() == static_cast<int>(std::io_errc::stream));
         assert(ec1.category() == std::iostream_category());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/defaultfloat.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/defaultfloat.pass.cpp
index 7f04bbc51e7..bb8c424a162 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/defaultfloat.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/defaultfloat.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::fixed));
     assert(!(ios.flags() & std::ios::scientific));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/fixed.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/fixed.pass.cpp
index 8dbb7a1d8b4..94cbf1a53d9 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/fixed.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/fixed.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::fixed(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::fixed);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/hexfloat.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/hexfloat.pass.cpp
index 24afef8b86e..c24d7f999d9 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/hexfloat.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/hexfloat.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     assert(&r == &ios);
     assert(ios.flags() & std::ios::fixed);
     assert(ios.flags() & std::ios::scientific);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/scientific.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/scientific.pass.cpp
index d84aa3775a0..c8a4819447b 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/scientific.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/floatfield.manip/scientific.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::scientific(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::scientific);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/boolalpha.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/boolalpha.pass.cpp
index de58c17f060..176267dd6fe 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/boolalpha.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/boolalpha.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::boolalpha(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::boolalpha);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noboolalpha.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noboolalpha.pass.cpp
index f67ddabaea3..27d61cee7aa 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noboolalpha.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noboolalpha.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     std::ios_base& r = std::noboolalpha(ios);
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::boolalpha));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowbase.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowbase.pass.cpp
index bd904ad6419..b730afa88ba 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowbase.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowbase.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     std::ios_base& r = std::noshowbase(ios);
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::showbase));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpoint.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpoint.pass.cpp
index 97d9198014c..0d9f33ea5c1 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpoint.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpoint.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     std::ios_base& r = std::noshowpoint(ios);
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::showpoint));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpos.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpos.pass.cpp
index 24f8bfca0b0..fa54cd64735 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpos.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noshowpos.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     std::ios_base& r = std::noshowpos(ios);
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::showpos));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noskipws.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noskipws.pass.cpp
index 5d24d3d4190..9ee5ea8e61a 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noskipws.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/noskipws.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     std::ios_base& r = std::noskipws(ios);
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::skipws));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nounitbuf.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nounitbuf.pass.cpp
index 61a7dd29e83..ce06e12bd11 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nounitbuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nounitbuf.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     std::ios_base& r = std::nounitbuf(ios);
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::unitbuf));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nouppercase.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nouppercase.pass.cpp
index 923a6ac754a..8e055462099 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nouppercase.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/nouppercase.pass.cpp
@@ -18,7 +18,7 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
@@ -26,4 +26,6 @@ int main()
     std::ios_base& r = std::nouppercase(ios);
     assert(&r == &ios);
     assert(!(ios.flags() & std::ios::uppercase));
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showbase.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showbase.pass.cpp
index d584d3128a8..7f1338c5dbf 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showbase.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showbase.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::showbase(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::showbase);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpoint.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpoint.pass.cpp
index 6cfb73633d1..03cf312d0f3 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpoint.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpoint.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::showpoint(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::showpoint);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpos.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpos.pass.cpp
index 06f1dd83620..2fb0d651154 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpos.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/showpos.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::showpos(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::showpos);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/skipws.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/skipws.pass.cpp
index b153bc84018..2c64cb8dfb1 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/skipws.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/skipws.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::skipws(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::skipws);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/unitbuf.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/unitbuf.pass.cpp
index 22bcf5eb99e..6acedc6a5c2 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/unitbuf.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/unitbuf.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::unitbuf(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::unitbuf);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/uppercase.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/uppercase.pass.cpp
index cc2a4bc45e8..e97763fff03 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/uppercase.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/fmtflags.manip/uppercase.pass.cpp
@@ -18,11 +18,13 @@
 
 struct testbuf : public std::streambuf {};
 
-int main()
+int main(int, char**)
 {
     testbuf sb;
     std::ios ios(&sb);
     std::ios_base& r = std::uppercase(ios);
     assert(&r == &ios);
     assert(ios.flags() & std::ios::uppercase);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.base/std.ios.manip/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/std.ios.manip/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/stream.types/streamoff.pass.cpp b/libcxx/test/std/input.output/iostreams.base/stream.types/streamoff.pass.cpp
index aaa5b871ac2..20b953d5527 100644
--- a/libcxx/test/std/input.output/iostreams.base/stream.types/streamoff.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/stream.types/streamoff.pass.cpp
@@ -13,8 +13,10 @@
 #include <ios>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert(std::is_integral<std::streamoff>::value, "");
     static_assert(std::is_signed<std::streamoff>::value, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.base/stream.types/streamsize.pass.cpp b/libcxx/test/std/input.output/iostreams.base/stream.types/streamsize.pass.cpp
index 67093232456..50fa21e8d52 100644
--- a/libcxx/test/std/input.output/iostreams.base/stream.types/streamsize.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.base/stream.types/streamsize.pass.cpp
@@ -13,8 +13,10 @@
 #include <ios>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert(std::is_integral<std::streamsize>::value, "");
     static_assert(std::is_signed<std::streamsize>::value, "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.requirements/iostream.limits.imbue/tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/iostreams.requirements/iostream.limits.imbue/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.requirements/iostream.limits.imbue/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.requirements/iostream.limits.imbue/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.requirements/iostreams.limits.pos/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostreams.requirements/iostreams.limits.pos/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.requirements/iostreams.limits.pos/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.requirements/iostreams.limits.pos/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.requirements/iostreams.threadsafety/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostreams.requirements/iostreams.threadsafety/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.requirements/iostreams.threadsafety/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.requirements/iostreams.threadsafety/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/iostreams.requirements/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/iostreams.requirements/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/iostreams.requirements/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/iostreams.requirements/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf.reqts/tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf.reqts/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf.reqts/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf.reqts/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.fail.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.fail.cpp
index b94714212b1..285485087b4 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.fail.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.fail.cpp
@@ -18,7 +18,9 @@
 
 std::streambuf &get();
 
-int main()
+int main(int, char**)
 {
     std::streambuf sb = get(); // expected-error {{calling a protected constructor}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp
index c2989929174..405c7299591 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/copy.pass.cpp
@@ -49,7 +49,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -82,4 +82,6 @@ int main()
         test<wchar_t> t;
         test<wchar_t> t2 = t;
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.fail.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.fail.cpp
index 76d47f2a237..ec7650ae04e 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.fail.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.fail.cpp
@@ -15,7 +15,9 @@
 
 #include <streambuf>
 
-int main()
+int main(int, char**)
 {
     std::basic_streambuf<char> sb;
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp
index 9eebf255760..15475d3d684 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.cons/default.pass.cpp
@@ -35,7 +35,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -54,4 +54,6 @@ int main()
         test<wchar_t> t;
         assert(t.getloc().name() == LOCALE_en_US_UTF_8);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekoff.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekoff.pass.cpp
index 741b71e38c2..b49fc2094ed 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekoff.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekoff.pass.cpp
@@ -24,11 +24,13 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
         assert(t.pubseekoff(0, std::ios_base::beg) == -1);
         assert(t.pubseekoff(0, std::ios_base::beg, std::ios_base::app) == -1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekpos.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekpos.pass.cpp
index 2e14de9d28f..1095c9148c7 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekpos.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubseekpos.pass.cpp
@@ -24,10 +24,12 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
         assert(t.pubseekpos(0, std::ios_base::app) == -1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsetbuf.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsetbuf.pass.cpp
index fae4dd78fd6..c0efb1710ab 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsetbuf.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsetbuf.pass.cpp
@@ -23,10 +23,12 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
         assert(t.pubsetbuf(0, 0) == &t);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsync.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsync.pass.cpp
index 8433a9f31a9..8d7528ee261 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsync.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.buffer/pubsync.pass.cpp
@@ -23,10 +23,12 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
         assert(t.pubsync() == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp
index ed1d43a8666..835944fcf31 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.locales/locales.pass.cpp
@@ -34,7 +34,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -48,4 +48,6 @@ int main()
                LOCALE_en_US_UTF_8);
         assert(t.getloc().name() == LOCALE_fr_FR_UTF_8);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/in_avail.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/in_avail.pass.cpp
index ea51ac64df1..6d11a8e8969 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/in_avail.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/in_avail.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -48,4 +48,6 @@ int main()
         t.setg(in, in+2, in+5);
         assert(t.in_avail() == 3);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sbumpc.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sbumpc.pass.cpp
index 4aa7a81818b..4ac2d6fe547 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sbumpc.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sbumpc.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -52,4 +52,6 @@ int main()
         assert(t.sbumpc() == 'B');
         assert(uflow_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetc.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetc.pass.cpp
index 2a48158fd41..8baefb279cf 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetc.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetc.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -52,4 +52,6 @@ int main()
         assert(t.sgetc() == 'A');
         assert(underflow_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetn.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetn.pass.cpp
index 59804043cb0..9088ed846b9 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetn.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/sgetn.pass.cpp
@@ -31,10 +31,12 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(xsgetn_called == 0);
     assert(t.sgetn(0, 0) == 10);
     assert(xsgetn_called == 1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/snextc.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/snextc.pass.cpp
index 830f27282ef..54965bca2fc 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/snextc.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.get/snextc.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -52,4 +52,6 @@ int main()
         assert(t.snextc() == 'C');
         assert(uflow_called == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sputbackc.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sputbackc.pass.cpp
index a2546b810df..3b63ba3cef9 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sputbackc.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sputbackc.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -52,4 +52,6 @@ int main()
         assert(t.sputbackc('A') == 'a');
         assert(pbackfail_called == 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sungetc.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sungetc.pass.cpp
index dcdec61a3d4..07c1600b0b2 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sungetc.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.pback/sungetc.pass.cpp
@@ -38,7 +38,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -52,4 +52,6 @@ int main()
         assert(t.sungetc() == 'a');
         assert(pbackfail_called == 2);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputc.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputc.pass.cpp
index 3d04924b160..989b61d4e19 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputc.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputc.pass.cpp
@@ -42,7 +42,7 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -59,4 +59,6 @@ int main()
         assert(out[0] == 'A');
         assert(out[1] == 'B');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputn.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputn.pass.cpp
index bb865636ca3..01bd9d487d8 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputn.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.members/streambuf.pub.put/sputn.pass.cpp
@@ -31,10 +31,12 @@ protected:
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(xsputn_called == 0);
     assert(t.sputn(0, 0) == 5);
     assert(xsputn_called == 1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp
index 0c1cd4efbf9..6109a6aa471 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/assign.pass.cpp
@@ -50,7 +50,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -89,4 +89,6 @@ int main()
         test<wchar_t> t2;
         t2 = t;
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp
index 6ece9aa57cf..2809d63124f 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.assign/swap.pass.cpp
@@ -59,7 +59,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -98,4 +98,6 @@ int main()
         test<wchar_t> t2;
         t2.swap(t);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/gbump.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/gbump.pass.cpp
index 015a7daa2f7..161461dee95 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/gbump.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/gbump.pass.cpp
@@ -41,7 +41,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -55,4 +55,6 @@ int main()
         t.setg(in, in+1, in+sizeof(in)/sizeof(in[0]));
         t.gbump(3);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/setg.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/setg.pass.cpp
index 74152974c07..b303465f02d 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/setg.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.get.area/setg.pass.cpp
@@ -33,7 +33,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -45,4 +45,6 @@ int main()
         wchar_t in[] = L"ABC";
         t.setg(in, in+1, in+sizeof(in)/sizeof(in[0]));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump.pass.cpp
index 92b869d31e5..e151d32273c 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump.pass.cpp
@@ -41,7 +41,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -57,4 +57,6 @@ int main()
         t.pbump(3);
         t.pbump(1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump2gig.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump2gig.pass.cpp
index 5811c90196f..eee48f3dfdb 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump2gig.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/pbump2gig.pass.cpp
@@ -26,7 +26,7 @@ struct SB : std::stringbuf
   const char* pubpptr() const { return pptr(); }
 };
 
-int main()
+int main(int, char**)
 {
 #ifndef TEST_HAS_NO_EXCEPTIONS
     try {
@@ -40,4 +40,6 @@ int main()
     catch (const std::length_error &) {} // maybe the string can't take 2GB
     catch (const std::bad_alloc    &) {} // maybe we don't have enough RAM
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/setp.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/setp.pass.cpp
index 12f955360c9..6ca36227b53 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/setp.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.protected/streambuf.put.area/setp.pass.cpp
@@ -33,7 +33,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test<char> t;
@@ -45,4 +45,6 @@ int main()
         wchar_t in[] = L"ABC";
         t.setp(in, in+sizeof(in)/sizeof(in[0]));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.buffer/tested_elsewhere.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.buffer/tested_elsewhere.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.buffer/tested_elsewhere.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.buffer/tested_elsewhere.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/showmanyc.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/showmanyc.pass.cpp
index b31408e952d..5a238e88455 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/showmanyc.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/showmanyc.pass.cpp
@@ -25,8 +25,10 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     test<char> t;
     assert(t.in_avail() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/uflow.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/uflow.pass.cpp
index 1d1ee519f58..2f86c3b1a96 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/uflow.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/uflow.pass.cpp
@@ -25,8 +25,10 @@ struct test
 
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.sgetc() == -1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/underflow.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/underflow.pass.cpp
index 2422c52e54b..1d2ce7c5c23 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/underflow.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/underflow.pass.cpp
@@ -22,8 +22,10 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.sgetc() == -1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/xsgetn.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/xsgetn.pass.cpp
index 7c5f6b9d6fe..f5a95821b28 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/xsgetn.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.get/xsgetn.pass.cpp
@@ -30,7 +30,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     char input[7] = "123456";
@@ -38,4 +38,6 @@ int main()
     char output[sizeof(input)] = {0};
     assert(t.sgetn(output, 10) == 7);
     assert(std::strcmp(input, output) == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.locales/nothing_to_do.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.locales/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.locales/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.locales/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.pback/pbackfail.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.pback/pbackfail.pass.cpp
index 1f243e958d6..217ff8c32fc 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.pback/pbackfail.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.pback/pbackfail.pass.cpp
@@ -24,8 +24,10 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.sputbackc('A') == -1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/overflow.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/overflow.pass.cpp
index ae52b9539ee..e067088f50b 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/overflow.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/overflow.pass.cpp
@@ -22,8 +22,10 @@ struct test
     test() {}
 };
 
-int main()
+int main(int, char**)
 {
     test t;
     assert(t.sputc('A') == -1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.pass.cpp
index 15d37404122..1c30c8f2836 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/streambuf.virtuals/streambuf.virt.put/xsputn.pass.cpp
@@ -30,7 +30,7 @@ struct test
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         test t;
@@ -41,4 +41,6 @@ int main()
         assert(t.sputn(in, sizeof(in)) == sizeof(in));
         assert(std::strcmp(in, out) == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/stream.buffers/streambuf/types.pass.cpp b/libcxx/test/std/input.output/stream.buffers/streambuf/types.pass.cpp
index d6ea963df27..434f8e3ec12 100644
--- a/libcxx/test/std/input.output/stream.buffers/streambuf/types.pass.cpp
+++ b/libcxx/test/std/input.output/stream.buffers/streambuf/types.pass.cpp
@@ -22,7 +22,7 @@
 #include <streambuf>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::streambuf::char_type, char>::value), "");
     static_assert((std::is_same<std::streambuf::traits_type, std::char_traits<char> >::value), "");
@@ -35,4 +35,6 @@ int main()
     static_assert((std::is_same<std::wstreambuf::int_type, std::char_traits<wchar_t>::int_type>::value), "");
     static_assert((std::is_same<std::wstreambuf::pos_type, std::char_traits<wchar_t>::pos_type>::value), "");
     static_assert((std::is_same<std::wstreambuf::off_type, std::char_traits<wchar_t>::off_type>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/member_swap.pass.cpp
index cb4644aad43..d0a5863ed84 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/member_swap.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream ss0(" 123 456");
@@ -52,4 +52,6 @@ int main()
         ss0 >> i;
         assert(i == 321);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/move.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/move.pass.cpp
index b906db8d5bf..5677959438f 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/move.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream ss0(" 123 456");
@@ -82,4 +82,6 @@ int main()
         s1 >> s;
         assert(s == L"Dddddddddddddddddd");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/nonmember_swap.pass.cpp
index 09b6e4b3996..b8b00310dbe 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.assign/nonmember_swap.pass.cpp
@@ -19,7 +19,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream ss0(" 123 456");
@@ -55,4 +55,6 @@ int main()
         ss0 >> i;
         assert(i == 321);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/default.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/default.pass.cpp
index 327c4ca124d..414c2269581 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/default.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream ss;
@@ -42,4 +42,6 @@ int main()
         assert(ss.good());
         assert(ss.str() == L"");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/move.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/move.pass.cpp
index c5b144b0920..27eb5a745c8 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/move.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream ss0(" 123 456");
@@ -44,4 +44,6 @@ int main()
         ss >> i;
         assert(i == 456);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/string.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/string.pass.cpp
index cf3c7d89130..04733d6042f 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.cons/string.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream ss(" 123 456");
@@ -63,4 +63,6 @@ int main()
         ss >> i;
         assert(i == 456);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.members/str.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.members/str.pass.cpp
index 9b706a535ac..4c010e2b434 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/istringstream.members/str.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/istringstream.members/str.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream ss(" 123 456");
@@ -52,4 +52,6 @@ int main()
         ss >> i;
         assert(i == 789);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/istringstream/types.pass.cpp b/libcxx/test/std/input.output/string.streams/istringstream/types.pass.cpp
index 0f256cbbdd4..97319644229 100644
--- a/libcxx/test/std/input.output/string.streams/istringstream/types.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/istringstream/types.pass.cpp
@@ -23,7 +23,7 @@
 #include <sstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_istream<char>, std::basic_istringstream<char> >::value), "");
     static_assert((std::is_same<std::basic_istringstream<char>::char_type, char>::value), "");
@@ -32,4 +32,6 @@ int main()
     static_assert((std::is_same<std::basic_istringstream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_istringstream<char>::off_type, std::char_traits<char>::off_type>::value), "");
     static_assert((std::is_same<std::basic_istringstream<char>::allocator_type, std::allocator<char> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/member_swap.pass.cpp
index af5622ee2c9..01cc58ae6ae 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/member_swap.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream ss0(" 123 456");
@@ -44,4 +44,6 @@ int main()
         ss0 << i << ' ' << 567;
         assert(ss0.str() == L"234 567");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/move.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/move.pass.cpp
index f44b0fba41a..bad3c7316d2 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/move.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream ss0(" 123 456");
@@ -42,4 +42,6 @@ int main()
         ss << i << ' ' << 567;
         assert(ss.str() == L"234 5676");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/nonmember_swap.pass.cpp
index 0793fd295cf..d251e6e085f 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.assign/nonmember_swap.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream ss0(" 123 456");
@@ -44,4 +44,6 @@ int main()
         ss0 << i << ' ' << 567;
         assert(ss0.str() == L"234 567");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/default.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/default.pass.cpp
index 79e0f614c5a..f772a904007 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/default.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream ss;
@@ -42,4 +42,6 @@ int main()
         assert(ss.good());
         assert(ss.str() == L"");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/move.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/move.pass.cpp
index 569310174b8..3b562bafd52 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/move.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream ss0(" 123 456");
@@ -40,4 +40,6 @@ int main()
         ss << i << ' ' << 567;
         assert(ss.str() == L"234 5676");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/string.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/string.pass.cpp
index 8d64dd5e5f1..98782dce1f6 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.cons/string.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream ss(" 123 456");
@@ -55,4 +55,6 @@ int main()
         ss << i << ' ' << 567;
         assert(ss.str() == L"234 5676");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.members/str.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.members/str.pass.cpp
index d74acf3a588..56a85159cca 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.members/str.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/ostringstream.members/str.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream ss(" 123 456");
@@ -48,4 +48,6 @@ int main()
         ss << L"abc";
         assert(ss.str() == L"abc9");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/ostringstream/types.pass.cpp b/libcxx/test/std/input.output/string.streams/ostringstream/types.pass.cpp
index 15e7dc61faf..0da5f98d46f 100644
--- a/libcxx/test/std/input.output/string.streams/ostringstream/types.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/ostringstream/types.pass.cpp
@@ -23,7 +23,7 @@
 #include <sstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_ostream<char>, std::basic_ostringstream<char> >::value), "");
     static_assert((std::is_same<std::basic_ostringstream<char>::char_type, char>::value), "");
@@ -32,4 +32,6 @@ int main()
     static_assert((std::is_same<std::basic_ostringstream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_ostringstream<char>::off_type, std::char_traits<char>::off_type>::value), "");
     static_assert((std::is_same<std::basic_ostringstream<char>::allocator_type, std::allocator<char> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp
index b5dce8fb914..6977d3189cf 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/member_swap.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -60,4 +60,6 @@ int main()
         assert(buf.str() == L"testing");
         assert(buf1.str() == L"");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp
index 2a469ebb79a..653edc0d19c 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/move.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -54,4 +54,6 @@ int main()
         buf = move(buf1);
         assert(buf.str() == L"testing");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp
index 5a57f902af3..38562fc3220 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.assign/nonmember_swap.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -62,4 +62,6 @@ int main()
         assert(buf.str() == L"testing");
         assert(buf1.str() == L"");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp
index 2121a7a842e..836509f2fdd 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/default.pass.cpp
@@ -31,7 +31,7 @@ struct testbuf
     }
 };
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf;
@@ -49,4 +49,6 @@ int main()
         testbuf<wchar_t> buf;
         buf.check();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp
index 70eff738492..a3cccd39c87 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/move.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf1("testing");
@@ -48,4 +48,6 @@ int main()
         std::wstringbuf buf(move(buf1));
         assert(buf.str() == L"testing");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp
index 607d314255b..de211c80ea1 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.cons/string.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf("testing");
@@ -43,4 +43,6 @@ int main()
         std::wstringbuf buf(L"testing", std::ios_base::out);
         assert(buf.str() == L"testing");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp
index baf406b696c..78b572454a5 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.members/str.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf buf("testing");
@@ -30,4 +30,6 @@ int main()
         buf.str(L"another test");
         assert(buf.str() == L"another test");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp
index 0f833070525..c9fdd0abcc9 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/overflow.pass.cpp
@@ -34,7 +34,7 @@ struct testbuf
     void pbump(int n) {base::pbump(n);}
 };
 
-int main()
+int main(int, char**)
 {
     {  // sanity check
     testbuf<char> tb("");
@@ -97,4 +97,6 @@ int main()
         assert(sb.sputc('2') == '2');
         assert(sb.str() == "abc12");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp
index dfbe2084b9d..458e393c8ec 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/pbackfail.pass.cpp
@@ -32,7 +32,7 @@ struct testbuf
     void pbump(int n) {base::pbump(n);}
 };
 
-int main()
+int main(int, char**)
 {
     {  // sanity check
     testbuf<char> tb("");
@@ -92,4 +92,6 @@ int main()
         assert(sb.pbackfail(std::char_traits<wchar_t>::eof()) == std::char_traits<wchar_t>::eof());
         assert(sb.str() == L"133");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
index dbe117eaa17..1bee5c216a5 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekoff.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf sb(std::ios_base::in);
@@ -163,4 +163,6 @@ int main()
         assert(sb.sputc(L'c') == L'c');
         assert(sb.str() == L"0123456c89");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp
index 7d687e070c1..fde91e74ba0 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/seekpos.pass.cpp
@@ -17,7 +17,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf sb("0123456789", std::ios_base::in);
@@ -73,4 +73,6 @@ int main()
         assert(sb.sputc(L'3') == L'3');
         assert(sb.str() == L"0123456789");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp
index 99bc75e6c8a..f833debe39d 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/setbuf.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringbuf sb("0123456789");
@@ -28,4 +28,6 @@ int main()
         assert(sb.pubsetbuf(0, 0) == &sb);
         assert(sb.str() == L"0123456789");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
index c3244985749..23b77d229ca 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/stringbuf.virtuals/underflow.pass.cpp
@@ -28,7 +28,7 @@ struct testbuf
     void pbump(int n) {base::pbump(n);}
 };
 
-int main()
+int main(int, char**)
 {
     {
         testbuf<char> sb("123");
@@ -66,4 +66,6 @@ int main()
         assert(sb.underflow() == L'4');
         assert(sb.underflow() == L'4');
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp b/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp
index 29d651fc5e5..c27db853599 100644
--- a/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringbuf/types.pass.cpp
@@ -23,7 +23,7 @@
 #include <sstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_streambuf<char>, std::basic_stringbuf<char> >::value), "");
     static_assert((std::is_same<std::basic_stringbuf<char>::char_type, char>::value), "");
@@ -32,4 +32,6 @@ int main()
     static_assert((std::is_same<std::basic_stringbuf<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_stringbuf<char>::off_type, std::char_traits<char>::off_type>::value), "");
     static_assert((std::is_same<std::basic_stringbuf<char>::allocator_type, std::allocator<char> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.cons/default.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.cons/default.pass.cpp
index 571c3dc658e..11cf288fcc9 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.cons/default.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.cons/default.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringstream ss;
@@ -42,4 +42,6 @@ int main()
         assert(ss.good());
         assert(ss.str() == L"");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.cons/move.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.cons/move.pass.cpp
index 671aee55397..2a73ad9c215 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.cons/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.cons/move.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringstream ss0(" 123 456 ");
@@ -48,4 +48,6 @@ int main()
         ss << i << ' ' << 123;
         assert(ss.str() == L"456 1236 ");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.cons/move2.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.cons/move2.pass.cpp
index 4527cae33f6..044e62824ca 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.cons/move2.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.cons/move2.pass.cpp
@@ -21,7 +21,7 @@
 #include <cassert>
 #include <cstddef>
 
-int main()
+int main(int, char**)
 {
     std::vector<std::istringstream> vecis;
     vecis.push_back(std::istringstream());
@@ -34,4 +34,6 @@ int main()
         vecis[n].seekg(0, std::ios_base::beg);
         assert(vecis[n].str().size() == 31);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.cons/string.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.cons/string.pass.cpp
index 7bc383f9a4a..29c81b3be62 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.cons/string.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.cons/string.pass.cpp
@@ -27,7 +27,7 @@ struct NoDefaultAllocator : std::allocator<T>
 };
 
 
-int main()
+int main(int, char**)
 {
     {
         std::stringstream ss(" 123 456 ");
@@ -64,4 +64,6 @@ int main()
     //  This test is not required by the standard, but *where else* could it get the allocator?
         assert(sb.str().get_allocator() == s.get_allocator());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/member_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/member_swap.pass.cpp
index 07d3a1dea9d..2e0f4471a1c 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/member_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/member_swap.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringstream ss0(" 123 456 ");
@@ -52,4 +52,6 @@ int main()
         ss0 << i << ' ' << 123;
         assert(ss0.str() == L"456 123");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/move.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/move.pass.cpp
index 0332924a69f..c3088679ed6 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/move.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/move.pass.cpp
@@ -18,7 +18,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringstream ss0(" 123 456 ");
@@ -50,4 +50,6 @@ int main()
         ss << i << ' ' << 123;
         assert(ss.str() == L"456 1236 ");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/nonmember_swap.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/nonmember_swap.pass.cpp
index 3225b273e68..06a95dcb394 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/nonmember_swap.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.cons/stringstream.assign/nonmember_swap.pass.cpp
@@ -19,7 +19,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringstream ss0(" 123 456 ");
@@ -55,4 +55,6 @@ int main()
         ss0 << i << ' ' << 123;
         assert(ss0.str() == L"456 123");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream.members/str.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream.members/str.pass.cpp
index 392a1680e5c..1dc655193b8 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream.members/str.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream.members/str.pass.cpp
@@ -16,7 +16,7 @@
 #include <sstream>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     {
         std::stringstream ss(" 123 456 ");
@@ -63,4 +63,6 @@ int main()
         ss.write("\xd1", 1);
         assert(ss.str().length() == 1);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/input.output/string.streams/stringstream/types.pass.cpp b/libcxx/test/std/input.output/string.streams/stringstream/types.pass.cpp
index e05048a2df1..580ccb9a4e6 100644
--- a/libcxx/test/std/input.output/string.streams/stringstream/types.pass.cpp
+++ b/libcxx/test/std/input.output/string.streams/stringstream/types.pass.cpp
@@ -23,7 +23,7 @@
 #include <sstream>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_base_of<std::basic_iostream<char>, std::basic_stringstream<char> >::value), "");
     static_assert((std::is_same<std::basic_stringstream<char>::char_type, char>::value), "");
@@ -32,4 +32,6 @@ int main()
     static_assert((std::is_same<std::basic_stringstream<char>::pos_type, std::char_traits<char>::pos_type>::value), "");
     static_assert((std::is_same<std::basic_stringstream<char>::off_type, std::char_traits<char>::off_type>::value), "");
     static_assert((std::is_same<std::basic_stringstream<char>::allocator_type, std::allocator<char> >::value), "");
+
+  return 0;
 }