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

424 files changed, 1293 insertions, 443 deletions

diff --git a/libcxx/test/std/strings/basic.string.hash/enabled_hashes.pass.cpp b/libcxx/test/std/strings/basic.string.hash/enabled_hashes.pass.cpp
index 10504c50151..0fecb1bb081 100644
--- a/libcxx/test/std/strings/basic.string.hash/enabled_hashes.pass.cpp
+++ b/libcxx/test/std/strings/basic.string.hash/enabled_hashes.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "poisoned_hash_helper.hpp"
 
-int main() {
+int main(int, char**) {
   test_library_hash_specializations_available();
   {
     test_hash_enabled_for_type<std::string>();
@@ -30,4 +30,6 @@ int main() {
     test_hash_enabled_for_type<std::u32string>();
 #endif
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string.hash/strings.pass.cpp b/libcxx/test/std/strings/basic.string.hash/strings.pass.cpp
index ea97e64f203..c2a2ef95647 100644
--- a/libcxx/test/std/strings/basic.string.hash/strings.pass.cpp
+++ b/libcxx/test/std/strings/basic.string.hash/strings.pass.cpp
@@ -40,7 +40,7 @@ test()
     assert(h(s1) != h(s2));
 }
 
-int main()
+int main(int, char**)
 {
     test<std::string>();
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -51,4 +51,6 @@ int main()
     test<std::u32string>();
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
     test<std::wstring>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string.literals/literal.pass.cpp b/libcxx/test/std/strings/basic.string.literals/literal.pass.cpp
index eed5c9420ac..a51d0d9ac8c 100644
--- a/libcxx/test/std/strings/basic.string.literals/literal.pass.cpp
+++ b/libcxx/test/std/strings/basic.string.literals/literal.pass.cpp
@@ -21,7 +21,7 @@
 #endif
 
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals::string_literals;
 
@@ -54,4 +54,6 @@ int main()
     Lfoo  =  L"ABC"s;     assert( Lfoo ==  L"ABC");   assert( Lfoo == std::wstring  ( L"ABC"));
     ufoo  =  u"ABC"s;     assert( ufoo ==  u"ABC");   assert( ufoo == std::u16string( u"ABC"));
     Ufoo  =  U"ABC"s;     assert( Ufoo ==  U"ABC");   assert( Ufoo == std::u32string( U"ABC"));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string.literals/literal1.fail.cpp b/libcxx/test/std/strings/basic.string.literals/literal1.fail.cpp
index 129d2844777..be4604059fe 100644
--- a/libcxx/test/std/strings/basic.string.literals/literal1.fail.cpp
+++ b/libcxx/test/std/strings/basic.string.literals/literal1.fail.cpp
@@ -12,9 +12,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using std::string;
 
     string foo  =   ""s;  // should fail w/conversion operator not found
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string.literals/literal1.pass.cpp b/libcxx/test/std/strings/basic.string.literals/literal1.pass.cpp
index 5134ec79aaa..92777c4f428 100644
--- a/libcxx/test/std/strings/basic.string.literals/literal1.pass.cpp
+++ b/libcxx/test/std/strings/basic.string.literals/literal1.pass.cpp
@@ -12,9 +12,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals;
 
     std::string foo  =   ""s;
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string.literals/literal2.fail.cpp b/libcxx/test/std/strings/basic.string.literals/literal2.fail.cpp
index 3ebbfa24c13..54a0a9e405b 100644
--- a/libcxx/test/std/strings/basic.string.literals/literal2.fail.cpp
+++ b/libcxx/test/std/strings/basic.string.literals/literal2.fail.cpp
@@ -12,7 +12,9 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::string foo  =   ""s;  // should fail w/conversion operator not found
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string.literals/literal2.pass.cpp b/libcxx/test/std/strings/basic.string.literals/literal2.pass.cpp
index ac41ce94c9b..6f73ae9a103 100644
--- a/libcxx/test/std/strings/basic.string.literals/literal2.pass.cpp
+++ b/libcxx/test/std/strings/basic.string.literals/literal2.pass.cpp
@@ -12,9 +12,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals::string_literals;
 
     std::string foo  =   ""s;
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string.literals/literal3.pass.cpp b/libcxx/test/std/strings/basic.string.literals/literal3.pass.cpp
index c5ca6708add..b7a8d553687 100644
--- a/libcxx/test/std/strings/basic.string.literals/literal3.pass.cpp
+++ b/libcxx/test/std/strings/basic.string.literals/literal3.pass.cpp
@@ -12,9 +12,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std;
 
     string foo  =   ""s;
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/allocator_mismatch.fail.cpp b/libcxx/test/std/strings/basic.string/allocator_mismatch.fail.cpp
index ae63acfcec1..1d016991f0c 100644
--- a/libcxx/test/std/strings/basic.string/allocator_mismatch.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/allocator_mismatch.fail.cpp
@@ -11,7 +11,9 @@
 
 #include <string>
 
-int main()
+int main(int, char**)
 {
     std::basic_string<char, std::char_traits<char>, std::allocator<int> > s;
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/char.bad.fail.cpp b/libcxx/test/std/strings/basic.string/char.bad.fail.cpp
index d78cb6aad98..bace91c3222 100644
--- a/libcxx/test/std/strings/basic.string/char.bad.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/char.bad.fail.cpp
@@ -26,7 +26,7 @@ private:
     int two;
 };
 
-int main()
+int main(int, char**)
 {
     {
 //  array
@@ -49,4 +49,6 @@ int main()
     std::basic_string<NotStandardLayout, test_traits<NotStandardLayout> > s;
 //  expected-error-re@string:* {{static_assert failed{{.*}} "Character type of basic_string must be standard-layout"}}
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.access/at.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/at.pass.cpp
index 6515e272721..514d1a894ce 100644
--- a/libcxx/test/std/strings/basic.string/string.access/at.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/at.pass.cpp
@@ -54,7 +54,7 @@ test(S s, typename S::size_type pos)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -74,4 +74,6 @@ int main()
     test(S("123"), 3);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.access/back.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/back.pass.cpp
index b4108010ac3..3831da0845c 100644
--- a/libcxx/test/std/strings/basic.string/string.access/back.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/back.pass.cpp
@@ -31,7 +31,7 @@ test(S s)
     assert(s.back() == typename S::value_type('z'));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -52,4 +52,6 @@ int main()
         assert(false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.access/db_back.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/db_back.pass.cpp
index 5034bfa11a9..e1cf707a6f0 100644
--- a/libcxx/test/std/strings/basic.string/string.access/db_back.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/db_back.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -46,8 +46,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.access/db_cback.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/db_cback.pass.cpp
index ddffb6cd787..e3e6db525e4 100644
--- a/libcxx/test/std/strings/basic.string/string.access/db_cback.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/db_cback.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -42,8 +42,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.access/db_cfront.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/db_cfront.pass.cpp
index e171883dc36..c9b2ba7c88e 100644
--- a/libcxx/test/std/strings/basic.string/string.access/db_cfront.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/db_cfront.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -42,8 +42,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.access/db_cindex.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/db_cindex.pass.cpp
index 770ab333c8b..c7b430efc98 100644
--- a/libcxx/test/std/strings/basic.string/string.access/db_cindex.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/db_cindex.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -44,8 +44,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.access/db_front.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/db_front.pass.cpp
index 7f2db649a12..73db2240510 100644
--- a/libcxx/test/std/strings/basic.string/string.access/db_front.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/db_front.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -46,8 +46,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.access/db_index.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/db_index.pass.cpp
index 40318e3988f..d3f2e8d28d0 100644
--- a/libcxx/test/std/strings/basic.string/string.access/db_index.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/db_index.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -44,8 +44,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.access/front.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/front.pass.cpp
index 5eee328feca..d51a12f0a77 100644
--- a/libcxx/test/std/strings/basic.string/string.access/front.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/front.pass.cpp
@@ -31,7 +31,7 @@ test(S s)
     assert(s.front() == typename S::value_type('z'));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -52,4 +52,6 @@ int main()
         assert(false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.access/index.pass.cpp b/libcxx/test/std/strings/basic.string/string.access/index.pass.cpp
index d529567c6fb..3a1224ca301 100644
--- a/libcxx/test/std/strings/basic.string/string.access/index.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.access/index.pass.cpp
@@ -20,7 +20,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -59,4 +59,6 @@ int main()
         assert(false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/capacity.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/capacity.pass.cpp
index 9f09dea1d3e..02187c5193a 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/capacity.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/capacity.pass.cpp
@@ -40,7 +40,7 @@ test(S s)
     S::allocator_type::throw_after = INT_MAX;
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::basic_string<char, std::char_traits<char>, test_allocator<char> > S;
@@ -60,4 +60,6 @@ int main()
     assert(s.capacity() > 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/clear.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/clear.pass.cpp
index 4f75e013401..914842bb7a6 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/clear.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/clear.pass.cpp
@@ -23,7 +23,7 @@ test(S s)
     assert(s.size() == 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -53,4 +53,6 @@ int main()
     test(s);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/empty.fail.cpp b/libcxx/test/std/strings/basic.string/string.capacity/empty.fail.cpp
index 2359dea942d..1bfa388b7b9 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/empty.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/empty.fail.cpp
@@ -20,8 +20,10 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     std::string c;
     c.empty();  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/empty.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/empty.pass.cpp
index 56d925d571c..47827db7f75 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/empty.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/empty.pass.cpp
@@ -24,7 +24,7 @@ test(const S& s)
     assert(s.empty() == (s.size() == 0));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -40,4 +40,6 @@ int main()
     test(S("12345678901234567890123456789012345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/length.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/length.pass.cpp
index 617d81a9205..b61ec488e27 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/length.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/length.pass.cpp
@@ -22,7 +22,7 @@ test(const S& s)
     assert(s.length() == s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -38,4 +38,6 @@ int main()
     test(S("12345678901234567890123456789012345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/max_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/max_size.pass.cpp
index 68017f45349..8f8c9a3fb42 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/max_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/max_size.pass.cpp
@@ -54,7 +54,7 @@ test(const S& s)
     test2(s);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -70,4 +70,6 @@ int main()
     test(S("12345678901234567890123456789012345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/over_max_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/over_max_size.pass.cpp
index 414b6742495..9832df536c9 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/over_max_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/over_max_size.pass.cpp
@@ -35,7 +35,7 @@ test(const S& s)
     assert ( false );
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -51,4 +51,6 @@ int main()
     test(S("12345678901234567890123456789012345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp
index 33699a79932..f49125cec98 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/reserve.pass.cpp
@@ -65,7 +65,7 @@ test(S s, typename S::size_type res_arg)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -131,4 +131,6 @@ int main()
     }
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/resize_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/resize_size.pass.cpp
index ad37dc30a1e..8b545939e3d 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/resize_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/resize_size.pass.cpp
@@ -43,7 +43,7 @@ test(S s, typename S::size_type n, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -85,4 +85,6 @@ int main()
     test(S(), S::npos, S("not going to happen"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/resize_size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/resize_size_char.pass.cpp
index b9005341456..b5e5aff8424 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/resize_size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/resize_size_char.pass.cpp
@@ -43,7 +43,7 @@ test(S s, typename S::size_type n, typename S::value_type c, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -85,4 +85,6 @@ int main()
     test(S(), S::npos, 'a', S("not going to happen"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/shrink_to_fit.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/shrink_to_fit.pass.cpp
index ee91ac1676b..2c6ce0df6f9 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/shrink_to_fit.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/shrink_to_fit.pass.cpp
@@ -29,7 +29,7 @@ test(S s)
     assert(s.capacity() >= s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -59,4 +59,6 @@ int main()
     test(s);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.capacity/size.pass.cpp b/libcxx/test/std/strings/basic.string/string.capacity/size.pass.cpp
index 16b236eebb8..f3f89a5a6d8 100644
--- a/libcxx/test/std/strings/basic.string/string.capacity/size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.capacity/size.pass.cpp
@@ -22,7 +22,7 @@ test(const S& s, typename S::size_type c)
     assert(s.size() == c);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -38,4 +38,6 @@ int main()
     test(S("12345678901234567890123456789012345678901234567890"), 50);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/T_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/T_size_size.pass.cpp
index 4f8158ea56d..38725979f9d 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/T_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/T_size_size.pass.cpp
@@ -91,7 +91,7 @@ test(SV sv, std::size_t pos, std::size_t n, const typename S::allocator_type& a)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
 
     {
@@ -183,4 +183,6 @@ int main()
     S s7(s.data(), 2);     // calls ctor(const char *, len)
     assert(s7 == "AB");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/alloc.pass.cpp
index a2518a184c0..765f61eafb8 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/alloc.pass.cpp
@@ -85,11 +85,13 @@ test2()
 
 #endif
 
-int main()
+int main(int, char**)
 {
     test<std::basic_string<char, std::char_traits<char>, test_allocator<char> > >();
 #if TEST_STD_VER >= 11
     test2<std::basic_string<char, std::char_traits<char>, min_allocator<char> > >();
     test2<std::basic_string<char, std::char_traits<char>, explicit_allocator<char> > >();
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/brace_assignment.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/brace_assignment.pass.cpp
index 44db3c14059..5e77e46b2e4 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/brace_assignment.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/brace_assignment.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
   // Test that assignment from {} and {ptr, len} are allowed and are not
   // ambiguous.
@@ -32,4 +32,6 @@ int main()
     s = {"abc", 2};
     assert(s == "ab");
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/char_assignment.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/char_assignment.pass.cpp
index e3976cffa94..53f676e3bb3 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/char_assignment.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/char_assignment.pass.cpp
@@ -28,7 +28,7 @@ test(S s1, typename S::value_type s2)
     assert(s1.capacity() >= s1.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -46,4 +46,6 @@ int main()
     test(S("1234567890123456789012345678901234567890123456789012345678901234567890"), 'a');
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/copy.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/copy.pass.cpp
index f2cfa8a0e37..0024f2defac 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/copy.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/copy.pass.cpp
@@ -28,7 +28,7 @@ test(S s1)
     assert(s2.get_allocator() == s1.get_allocator());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -46,4 +46,6 @@ int main()
     test(S("1234567890123456789012345678901234567890123456789012345678901234567890", A()));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/copy_alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/copy_alloc.pass.cpp
index 57a17e8abb9..a635f017e80 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/copy_alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/copy_alloc.pass.cpp
@@ -87,7 +87,7 @@ test(S s1, const typename S::allocator_type& a)
     assert(s2.get_allocator() == a);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -127,4 +127,6 @@ int main()
     }
 #endif
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/copy_assignment.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/copy_assignment.pass.cpp
index a3c1389dafe..8b3b7ac04c8 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/copy_assignment.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/copy_assignment.pass.cpp
@@ -27,7 +27,7 @@ test(S s1, const S& s2)
     assert(s1.capacity() >= s1.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -76,4 +76,6 @@ int main()
     assert(s == "a");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/default_noexcept.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/default_noexcept.pass.cpp
index 1ab00b60e11..301876b2c3b 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/default_noexcept.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/default_noexcept.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 #include "test_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         typedef std::string C;
@@ -35,4 +35,6 @@ int main()
         typedef std::basic_string<char, std::char_traits<char>, limited_allocator<char, 10>> C;
         static_assert(!std::is_nothrow_default_constructible<C>::value, "");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/dtor_noexcept.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/dtor_noexcept.pass.cpp
index 5b57fe3cadc..d1372d29643 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/dtor_noexcept.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/dtor_noexcept.pass.cpp
@@ -32,7 +32,7 @@ struct throwing_alloc
 std::string s;
 std::wstring ws;
 
-int main()
+int main(int, char**)
 {
     {
         typedef std::string C;
@@ -48,4 +48,6 @@ int main()
         static_assert(!std::is_nothrow_destructible<C>::value, "");
     }
 #endif // _LIBCPP_VERSION
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/implicit_deduction_guides.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/implicit_deduction_guides.pass.cpp
index 7eb364e6239..9e31d3e6f9e 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/implicit_deduction_guides.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/implicit_deduction_guides.pass.cpp
@@ -46,7 +46,7 @@ using BStr = std::basic_string<T, std::char_traits<T>, Alloc>;
 // (13) basic_string(initializer_list<CharT>, A const& = A())
 // (14) basic_string(BSV, A const& = A())
 // (15) basic_string(const T&, size_type, size_type, A const& = A())
-int main()
+int main(int, char**)
 {
   using TestSizeT = test_allocator<char>::size_type;
   { // Testing (1)
@@ -313,4 +313,6 @@ int main()
     ASSERT_SAME_TYPE(decltype(w), ExpectW);
     assert(w == L"cd");
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/initializer_list.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/initializer_list.pass.cpp
index 3a8914cd3d8..a106203d49c 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/initializer_list.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/initializer_list.pass.cpp
@@ -18,7 +18,7 @@
 #include "test_allocator.h"
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s = {'a', 'b', 'c'};
@@ -40,4 +40,6 @@ int main()
         s = {L'a', L'b', L'c'};
         assert(s == L"abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/initializer_list_assignment.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/initializer_list_assignment.pass.cpp
index 6a512f27413..dcb9bb911b4 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/initializer_list_assignment.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/initializer_list_assignment.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s;
@@ -30,4 +30,6 @@ int main()
         s = {'a', 'b', 'c'};
         assert(s == "abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp
index 6966e6e5d24..042018cb532 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc.pass.cpp
@@ -56,7 +56,7 @@ test(It first, It last, const A& a)
     assert(s2.capacity() >= s2.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -116,4 +116,6 @@ int main()
     test(input_iterator<const char*>(s), input_iterator<const char*>(s+50), A());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.fail.cpp
index f87aac5f0e7..57fd550ac47 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.fail.cpp
@@ -35,7 +35,7 @@ class NotAnItertor {};
 template <typename T>
 struct NotAnAllocator { typedef T value_type; };
 
-int main()
+int main(int, char**)
 {
     { // Not an iterator at all
     std::basic_string s1{NotAnItertor{}, NotAnItertor{}, std::allocator<char>{}}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
@@ -52,4 +52,6 @@ int main()
     std::basic_string s1{s, s+10, NotAnAllocator<wchar_t>{}}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
     }
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp
index dac9ee33277..44daab4fcdc 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/iter_alloc_deduction.pass.cpp
@@ -36,7 +36,7 @@
 #include "../input_iterator.h"
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     const char* s = "12345678901234";
@@ -89,4 +89,6 @@ int main()
     assert(s1.size() == 10);
     assert(s1.compare(0, s1.size(), s, s1.size()) == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/move.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/move.pass.cpp
index 1c11368c7ea..729c8e80690 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/move.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/move.pass.cpp
@@ -32,7 +32,7 @@ test(S s0)
     assert(s2.get_allocator() == s1.get_allocator());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -48,4 +48,6 @@ int main()
     test(S("1", A()));
     test(S("1234567890123456789012345678901234567890123456789012345678901234567890", A()));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/move_alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/move_alloc.pass.cpp
index e426e2dc85d..63e349e71ce 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/move_alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/move_alloc.pass.cpp
@@ -34,7 +34,7 @@ test(S s0, const typename S::allocator_type& a)
 }
 
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -74,4 +74,6 @@ int main()
     test(S("1"), A());
     test(S("1234567890123456789012345678901234567890123456789012345678901234567890"), A());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/move_assign_noexcept.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/move_assign_noexcept.pass.cpp
index 88bc1231071..2a00898c1de 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/move_assign_noexcept.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/move_assign_noexcept.pass.cpp
@@ -62,7 +62,7 @@ struct some_alloc3
     typedef std::false_type is_always_equal;
 };
 
-int main()
+int main(int, char**)
 {
     {
         typedef std::string C;
@@ -93,4 +93,6 @@ int main()
         static_assert(!std::is_nothrow_move_assignable<C>::value, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/move_assignment.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/move_assignment.pass.cpp
index b039e79554f..9684fe7380a 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/move_assignment.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/move_assignment.pass.cpp
@@ -32,7 +32,7 @@ test(S s1, S s2)
     assert(s1.capacity() >= s1.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -70,4 +70,6 @@ int main()
            "1234567890123456789012345678901234567890123456789012345678901234567890"),
          S("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz"));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/move_noexcept.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/move_noexcept.pass.cpp
index 374183f99ff..ee839cf261c 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/move_noexcept.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/move_noexcept.pass.cpp
@@ -21,7 +21,7 @@
 #include "test_macros.h"
 #include "test_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         typedef std::string C;
@@ -39,4 +39,6 @@ int main()
         static_assert( std::is_nothrow_move_constructible<C>::value, "");
 #endif
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/pointer_alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/pointer_alloc.pass.cpp
index b68c5228a4b..d67f1231fd3 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/pointer_alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/pointer_alloc.pass.cpp
@@ -51,7 +51,7 @@ test(const charT* s, const A& a)
     assert(s2.capacity() >= s2.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -85,4 +85,6 @@ int main()
     test("123456798012345679801234567980123456798012345679801234567980", A());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/pointer_assignment.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/pointer_assignment.pass.cpp
index 1216f3f18cd..4a885485bea 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/pointer_assignment.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/pointer_assignment.pass.cpp
@@ -29,7 +29,7 @@ test(S s1, const typename S::value_type* s2)
     assert(s1.capacity() >= s1.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -69,4 +69,6 @@ int main()
          "abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/pointer_size_alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/pointer_size_alloc.pass.cpp
index 96457135ed1..75ad883fcf1 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/pointer_size_alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/pointer_size_alloc.pass.cpp
@@ -48,7 +48,7 @@ test(const charT* s, unsigned n, const A& a)
     assert(s2.capacity() >= s2.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -90,4 +90,6 @@ int main()
     assert(s == "a");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/size_char_alloc.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/size_char_alloc.pass.cpp
index 21ed485ef13..d509971910f 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/size_char_alloc.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/size_char_alloc.pass.cpp
@@ -80,7 +80,7 @@ test(Tp n, Tp c, const A& a)
     assert(s2.capacity() >= s2.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -120,4 +120,6 @@ int main()
     test(static_cast<char>(100), static_cast<char>(65), A());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view.fail.cpp
index d7a054073d4..61d5b3db4e9 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view.fail.cpp
@@ -15,8 +15,10 @@
 
 void foo ( const string &s ) {}
 
-int main()
+int main(int, char**)
 {
     std::string_view sv = "ABCDE";
     foo(sv);    // requires implicit conversion from string_view to string
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp
index f50d9e51981..b423c327dca 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view.pass.cpp
@@ -71,7 +71,7 @@ test(std::basic_string_view<charT> sv, const A& a)
   }
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -107,4 +107,6 @@ int main()
     test(SV("123456798012345679801234567980123456798012345679801234567980"), A());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_assignment.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_assignment.pass.cpp
index 9a50f62a7ae..942d990ee50 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_assignment.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view_assignment.pass.cpp
@@ -28,7 +28,7 @@ test(S s1, SV sv)
     assert(s1.capacity() >= s1.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -70,4 +70,6 @@ int main()
          SV("abcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyzabcdefghijklmnopqrstuvwxyz"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp
index 23e6668e69c..62ce16eca16 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.fail.cpp
@@ -31,10 +31,12 @@
 #include <cassert>
 #include <cstddef>
 
-int main()
+int main(int, char**)
 {
     {
     std::string_view sv = "12345678901234";
     std::basic_string s1{sv, 23}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp
index ee731581fb6..b3adc41464f 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view_deduction.pass.cpp
@@ -38,7 +38,7 @@
 #include "../input_iterator.h"
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::string_view sv = "12345678901234";
@@ -103,4 +103,6 @@ int main()
     assert(s1.size() == sv.size());
     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.fail.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.fail.cpp
index ce4e695377f..cff605677de 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.fail.cpp
@@ -37,10 +37,12 @@
 #include <cassert>
 #include <cstddef>
 
-int main()
+int main(int, char**)
 {
     {
     std::string_view sv = "12345678901234";
     std::basic_string s1{sv, 0, 4, 23}; // expected-error {{no viable constructor or deduction guide for deduction of template arguments of 'basic_string'}}
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp
index daba3bd1204..983ab78e4ce 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/string_view_size_size_deduction.pass.cpp
@@ -42,7 +42,7 @@
 #include "../input_iterator.h"
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     std::string_view sv = "12345678901234";
@@ -107,4 +107,6 @@ int main()
     assert(s1.size() == 4);
     assert(s1.compare(0, s1.size(), sv.data(), s1.size()) == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.cons/substr.pass.cpp b/libcxx/test/std/strings/basic.string/string.cons/substr.pass.cpp
index 05c53ac23db..44f29beec92 100644
--- a/libcxx/test/std/strings/basic.string/string.cons/substr.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.cons/substr.pass.cpp
@@ -140,7 +140,7 @@ void test2583()
 #endif
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -224,4 +224,6 @@ int main()
     test2583();
 #endif
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp
index 7d1c26418be..e2afe04202c 100644
--- a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.char.pass.cpp
@@ -16,7 +16,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -30,4 +30,6 @@ int main()
     assert ( s2.ends_with('e'));
     assert (!s2.ends_with('x'));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp
index 87b94042ffe..a4f8b1aa39c 100644
--- a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.ptr.pass.cpp
@@ -16,7 +16,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -59,4 +59,6 @@ int main()
     assert (!sNot.ends_with("abcde"));
     assert ( sNot.ends_with("def"));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp
index 3d75e23dac7..cbfffcfce98 100644
--- a/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ends_with/ends_with.string_view.pass.cpp
@@ -16,7 +16,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -68,4 +68,6 @@ int main()
     assert (!sNot.ends_with(sv5));
     assert ( sNot.ends_with(svNot));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp
index eedc9b991a2..fbae9fab7d2 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/begin.pass.cpp
@@ -30,7 +30,7 @@ test(S s)
     assert(b == cb);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -44,4 +44,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp
index 720ba53e738..9886d56bbd9 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/cbegin.pass.cpp
@@ -27,7 +27,7 @@ test(const S& s)
     assert(cb == s.begin());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -41,4 +41,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp
index 07d885aee88..1a3d30775f2 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/cend.pass.cpp
@@ -23,7 +23,7 @@ test(const S& s)
     assert(ce == s.end());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -37,4 +37,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp
index 2b8837fd3d2..687c34368ae 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/crbegin.pass.cpp
@@ -27,7 +27,7 @@ test(const S& s)
     assert(cb == s.rbegin());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -41,4 +41,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp
index c74b907fe7c..86aaad699d4 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/crend.pass.cpp
@@ -23,7 +23,7 @@ test(const S& s)
     assert(ce == s.rend());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -37,4 +37,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_2.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_2.pass.cpp
index 074fa84bd8d..46963239476 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_2.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_2.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -44,8 +44,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_3.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_3.pass.cpp
index 9c63eeafe39..7dbbbbb4cba 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_3.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_3.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -44,8 +44,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_4.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_4.pass.cpp
index c01b22662b6..1a46f86c28d 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_4.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_4.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string C;
@@ -46,8 +46,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_5.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_5.pass.cpp
index a5a8d917b93..77caf1b814a 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_5.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_5.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string C;
@@ -50,8 +50,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_6.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_6.pass.cpp
index b4c7fb38006..126c3661c39 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_6.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_6.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string C;
@@ -48,8 +48,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_7.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_7.pass.cpp
index 6a262e0f397..f1083a43954 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_7.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_7.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string C;
@@ -48,8 +48,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_8.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_8.pass.cpp
index f3b5656f766..c69f8ca4b03 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_8.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/db_iterators_8.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string C;
@@ -44,8 +44,10 @@ int main()
 
 #else
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
 
 #endif
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp
index 8d287f6f799..86b00a3706d 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/end.pass.cpp
@@ -33,7 +33,7 @@ test(S s)
     assert(static_cast<std::size_t>(ce - cs.begin()) == cs.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -47,4 +47,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/iterators.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/iterators.pass.cpp
index 3d907602317..08448b1fd89 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/iterators.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/iterators.pass.cpp
@@ -20,7 +20,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     { // N3644 testing
         typedef std::string C;
@@ -83,4 +83,6 @@ int main()
         assert ( !(ii1 != ii2 ));
         assert ( !(ii1 != cii ));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp
index 8de45475f62..479584c3708 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/rbegin.pass.cpp
@@ -30,7 +30,7 @@ test(S s)
     assert(b == cb);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -44,4 +44,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp b/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp
index 1edcb27af07..9b54058a60d 100644
--- a/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.iterators/rend.pass.cpp
@@ -33,7 +33,7 @@ test(S s)
     assert(static_cast<std::size_t>(ce - cs.rbegin()) == cs.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -47,4 +47,6 @@ int main()
     test(S("123"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/nothing_to_do.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/T_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/T_size_size.pass.cpp
index f2848295baf..43752406362 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/T_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/T_size_size.pass.cpp
@@ -71,7 +71,7 @@ test_npos(S s, SV sv, typename S::size_type pos, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -196,4 +196,6 @@ int main()
     s.append(sv, 0, std::string::npos);
     assert(s == "ABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZABCDEFGHIJKLMNOPQRSTUVWXYZ");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/initializer_list.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/initializer_list.pass.cpp
index 04483865d56..da74fb4e09c 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/initializer_list.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/initializer_list.pass.cpp
@@ -18,7 +18,7 @@
 #include "test_macros.h"
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("123");
@@ -31,4 +31,6 @@ int main()
         s.append({'a', 'b', 'c'});
         assert(s == "123abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/iterator.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/iterator.pass.cpp
index 08f554b34d4..8f280e828d9 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/iterator.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/iterator.pass.cpp
@@ -42,7 +42,7 @@ test_exceptions(S s, It first, It last)
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -219,4 +219,6 @@ int main()
     s.append(MoveIt(It(std::begin(p))), MoveIt(It(std::end(p) - 1)));
     assert(s == "ABCD");
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer.pass.cpp
index dec79a67cd1..eba693d0e3d 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer.pass.cpp
@@ -26,7 +26,7 @@ test(S s, const typename S::value_type* str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -76,4 +76,6 @@ int main()
     s_long.append(s_long.c_str());
     assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer_size.pass.cpp
index 2fb973ae983..c214ab7c2ac 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/pointer_size.pass.cpp
@@ -27,7 +27,7 @@ test(S s, const typename S::value_type* str, typename S::size_type n, S expected
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -85,4 +85,6 @@ int main()
     s_long.append(s_long.data(), s_long.size());
     assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/push_back.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/push_back.pass.cpp
index a2b9ad1e470..f1b34ad6cff 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/push_back.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/push_back.pass.cpp
@@ -31,7 +31,7 @@ test(S s, typename S::value_type c, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -56,4 +56,6 @@ int main()
     s.push_back(vl);
     s.push_back(vl);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/size_char.pass.cpp
index 59d0199a2bf..c4062489291 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/size_char.pass.cpp
@@ -26,7 +26,7 @@ test(S s, typename S::size_type n, typename S::value_type c, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -60,4 +60,6 @@ int main()
     test(S("12345678901234567890"), 10, 'a', S("12345678901234567890aaaaaaaaaa"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string.pass.cpp
index c0c625f2e22..5e551d7a2b1 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string.pass.cpp
@@ -26,7 +26,7 @@ test(S s, S str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -85,4 +85,6 @@ int main()
     assert(s == "a");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_size_size.pass.cpp
index 21ddd9bb225..37985d00115 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_size_size.pass.cpp
@@ -71,7 +71,7 @@ test_npos(S s, S str, typename S::size_type pos, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -133,4 +133,6 @@ int main()
     test_npos(S(), S("12345"), 5, S(""));
     test_npos(S(), S("12345"), 6, S("not happening"));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_view.pass.cpp
index 301fc77b704..d0fb1cc3315 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_append/string_view.pass.cpp
@@ -27,7 +27,7 @@ test(S s, SV sv, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -79,4 +79,6 @@ int main()
          S("1234567890123456789012345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp
index b0541712257..044b3724041 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/T_size_size.pass.cpp
@@ -70,7 +70,7 @@ test_npos(S s, SV sv, typename S::size_type pos, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -191,4 +191,6 @@ int main()
     s.assign(sv, 0, std::string::npos);
     assert(s == "ABCDEFGHIJKLMNOPQRSTUVWXYZ");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp
index 72097dae630..692b84b557d 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/initializer_list.pass.cpp
@@ -18,7 +18,7 @@
 #include "test_macros.h"
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("123");
@@ -31,4 +31,6 @@ int main()
         s.assign({'a', 'b', 'c'});
         assert(s == "abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
index 4bf805c99d6..c03b5efdfd5 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/iterator.pass.cpp
@@ -43,7 +43,7 @@ test_exceptions(S s, It first, It last)
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -204,4 +204,6 @@ int main()
     s.assign(p, p + 4);
     assert(s == "ABCD");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp
index 62a173a186d..325c354c56a 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer.pass.cpp
@@ -26,7 +26,7 @@ test(S s, const typename S::value_type* str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -74,4 +74,6 @@ int main()
     s_long.assign(s_long.c_str() + 30);
     assert(s_long == "nsectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp
index 442d8c00024..5d3fe262184 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/pointer_size.pass.cpp
@@ -27,7 +27,7 @@ test(S s, const typename S::value_type* str, typename S::size_type n, S expected
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -85,4 +85,6 @@ int main()
     s_long.assign(s_long.data() + 2, 8 );
     assert(s_long == "rem ipsu");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp
index 3d401c8a917..ac26f369ddb 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/rv_string.pass.cpp
@@ -27,7 +27,7 @@ test(S s, S str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -77,4 +77,6 @@ int main()
          S("12345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp
index 8c69b138f9f..4e5ecad2e9d 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/size_char.pass.cpp
@@ -26,7 +26,7 @@ test(S s, typename S::size_type n, typename S::value_type c, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -60,4 +60,6 @@ int main()
     test(S("12345678901234567890"), 10, 'a', S(10, 'a'));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp
index 274703a565d..fae45c80de0 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string.pass.cpp
@@ -37,7 +37,7 @@ testAlloc(S s, S str, const typename S::allocator_type& a)
     assert(s.get_allocator() == a);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -113,4 +113,6 @@ int main()
     static_assert(noexcept(S().assign(S())), "");  // LWG#2063
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp
index 76dd273455b..8e11b150e91 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_size_size.pass.cpp
@@ -71,7 +71,7 @@ test_npos(S s, S str, typename S::size_type pos, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -133,4 +133,6 @@ int main()
     test_npos(S(), S("12345"), 5, S(""));
     test_npos(S(), S("12345"), 6, S("not happening"));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp
index d445ad9b793..2d1158e41de 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_assign/string_view.pass.cpp
@@ -38,7 +38,7 @@ testAlloc(S s, SV sv, const typename S::allocator_type& a)
     assert(s.get_allocator() == a);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -101,4 +101,6 @@ int main()
     testAlloc(S(), SV("12345678901234567890"), min_allocator<char>());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_copy/copy.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_copy/copy.pass.cpp
index 81dc3329c43..778fb70c069 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_copy/copy.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_copy/copy.pass.cpp
@@ -49,7 +49,7 @@ test(S str, typename S::value_type* s, typename S::size_type n,
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -177,4 +177,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), s, 21, 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter.pass.cpp
index 1923c62b4d2..12b13d738cc 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter.pass.cpp
@@ -28,7 +28,7 @@ test(S s, typename S::difference_type pos, S expected)
     assert(i - s.begin() == pos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -62,4 +62,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), 19, S("abcdefghijklmnopqrs"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter_iter.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter_iter.pass.cpp
index 0eba9361d8a..a5e6d1251d1 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter_iter.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/iter_iter.pass.cpp
@@ -29,7 +29,7 @@ test(S s, typename S::difference_type pos, typename S::difference_type n, S expe
     assert(i - s.begin() == pos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -147,4 +147,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), 20, 0, S("abcdefghijklmnopqrst"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/pop_back.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/pop_back.pass.cpp
index e6f2a4e6035..e6490abcd2e 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/pop_back.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/pop_back.pass.cpp
@@ -26,7 +26,7 @@ test(S s, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -42,4 +42,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrs"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/size_size.pass.cpp
index a8e31c9c694..88dace52f8a 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_erase/size_size.pass.cpp
@@ -88,7 +88,7 @@ test(S s, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -298,4 +298,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S(""));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_char.pass.cpp
index d570428c054..ef6144dadb5 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_char.pass.cpp
@@ -32,7 +32,7 @@ test(S& s, typename S::const_iterator p, typename S::value_type c, S expected)
         assert(i == p);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -72,4 +72,6 @@ int main()
     test(s, s.begin()+6, 'C', S("a567ABC1432dcb"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_initializer_list.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_initializer_list.pass.cpp
index 0acc50b4549..6dd043c6db9 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_initializer_list.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_initializer_list.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("123456");
@@ -33,4 +33,6 @@ int main()
         assert(i - s.begin() == 3);
         assert(s == "123abc456");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_iter_iter.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_iter_iter.pass.cpp
index c1b16872928..6d4f1a6686e 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_iter_iter.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_iter_iter.pass.cpp
@@ -49,7 +49,7 @@ test_exceptions(S s, typename S::difference_type pos, It first, It last)
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -218,4 +218,6 @@ int main()
     s.insert(s.begin(), MoveIt(It(std::begin(p))), MoveIt(It(std::end(p) - 1)));
     assert(s == "ABCD");
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_size_char.pass.cpp
index ac29e3b3325..699b67924b1 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/iter_size_char.pass.cpp
@@ -28,7 +28,7 @@ test(S s, typename S::difference_type pos, typename S::size_type n,
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -166,4 +166,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), 20, 20, '1', S("abcdefghijklmnopqrst11111111111111111111"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_T_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_T_size_size.pass.cpp
index fb8c7e63a5c..2b54b67202b 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_T_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_T_size_size.pass.cpp
@@ -1729,7 +1729,7 @@ void test30()
     test_npos(S("abcdefghijklmnopqrst"), 10, SV("12345"), 6, S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -1838,4 +1838,6 @@ int main()
     assert(s == "");
     s.clear();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer.pass.cpp
index ee7ef204a33..24859fa8be2 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer.pass.cpp
@@ -47,7 +47,7 @@ test(S s, typename S::size_type pos, const typename S::value_type* str, S expect
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -233,4 +233,6 @@ int main()
     s_long.insert(0, s_long.c_str());
     assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer_size.pass.cpp
index 67a03400528..3dbd93f1df5 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_pointer_size.pass.cpp
@@ -48,7 +48,7 @@ test(S s, typename S::size_type pos, const typename S::value_type* str,
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -714,4 +714,6 @@ int main()
     s_long.insert(0, s_long.data(), s_long.size());
     assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_size_char.pass.cpp
index e64e9c997e3..dce8b7d7edb 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_size_char.pass.cpp
@@ -48,7 +48,7 @@ test(S s, typename S::size_type pos, typename S::size_type n,
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -218,4 +218,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), 21, 20, '1', S("can't happen"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string.pass.cpp
index 2f74fec3f79..93bc3f6d961 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string.pass.cpp
@@ -47,7 +47,7 @@ test(S s, typename S::size_type pos, S str, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -226,4 +226,6 @@ int main()
     assert(s == "a");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string_size_size.pass.cpp
index 23b8852b4c3..18a688a5d1f 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/size_string_size_size.pass.cpp
@@ -1727,7 +1727,7 @@ void test30()
     test_npos(S("abcdefghijklmnopqrst"), 10, S("12345"), 6, S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -1799,4 +1799,6 @@ int main()
     test30<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/string_view.pass.cpp
index 0596ce9849e..129389a9a7b 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_insert/string_view.pass.cpp
@@ -47,7 +47,7 @@ test(S s, typename S::size_type pos, SV sv, S expected)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -235,4 +235,6 @@ int main()
     s_long.insert(0, s_long.c_str());
     assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/char.pass.cpp
index 3c15f6f919e..2cc4496eb67 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/char.pass.cpp
@@ -25,7 +25,7 @@ test(S s, typename S::value_type str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -43,4 +43,6 @@ int main()
     test(S("12345678901234567890"), 'a', S("12345678901234567890a"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/initializer_list.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/initializer_list.pass.cpp
index 7f27559f0e6..689389eb7a6 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/initializer_list.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/initializer_list.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("123");
@@ -30,4 +30,6 @@ int main()
         s += {'a', 'b', 'c'};
         assert(s == "123abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/pointer.pass.cpp
index 3a769693518..a9edf17be5b 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/pointer.pass.cpp
@@ -25,7 +25,7 @@ test(S s, const typename S::value_type* str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -75,4 +75,6 @@ int main()
          S("1234567890123456789012345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/string.pass.cpp
index 53e1cacf4a1..f81d4bec0d2 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_op_plus_equal/string.pass.cpp
@@ -26,7 +26,7 @@ test(S s, S str, S expected)
     assert(s == expected);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -85,4 +85,6 @@ int main()
     assert(s == "a");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_initializer_list.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_initializer_list.pass.cpp
index 8e8a1f8ef9e..3df49f32535 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_initializer_list.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_initializer_list.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("123def456");
@@ -30,4 +30,6 @@ int main()
         s.replace(s.cbegin() + 3, s.cbegin() + 6, {'a', 'b', 'c'});
         assert(s == "123abc456");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_iter_iter.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_iter_iter.pass.cpp
index fc6f33beafe..47a1193be73 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_iter_iter.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_iter_iter.pass.cpp
@@ -963,7 +963,7 @@ void test8()
     test(S("abcdefghijklmnopqrst"), 20, 0, str, str+20, S("abcdefghijklmnopqrst12345678901234567890"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -1036,4 +1036,6 @@ int main()
     s.replace(s.begin(), s.end(), p, p + 4);
     assert(s == "EFGH");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer.pass.cpp
index ccbd0ff66fb..8ed1dc3df30 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer.pass.cpp
@@ -265,7 +265,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 20, 0, "12345678901234567890", S("abcdefghijklmnopqrst12345678901234567890"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -297,4 +297,6 @@ int main()
     s_long.replace(s_long.begin(), s_long.begin(), s_long.c_str());
     assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer_size.pass.cpp
index 79ae58fce2e..39b518c9146 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_pointer_size.pass.cpp
@@ -943,7 +943,7 @@ void test8()
     test(S("abcdefghijklmnopqrst"), 20, 0, "12345678901234567890", 20, S("abcdefghijklmnopqrst12345678901234567890"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -987,4 +987,6 @@ int main()
     s_long.replace(s_long.begin(), s_long.begin(), s_long.data(), s_long.size());
     assert(s_long == "Lorem ipsum dolor sit amet, consectetur/Lorem ipsum dolor sit amet, consectetur/");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_size_char.pass.cpp
index 8a79b733fe2..e60c69f7a27 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_size_char.pass.cpp
@@ -265,7 +265,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 20, 0, 20, '3', S("abcdefghijklmnopqrst33333333333333333333"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -281,4 +281,6 @@ int main()
     test2<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string.pass.cpp
index b47d2931b9b..7008736610f 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string.pass.cpp
@@ -264,7 +264,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 20, 0, S("12345678901234567890"), S("abcdefghijklmnopqrst12345678901234567890"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -289,4 +289,6 @@ int main()
     assert(s == "a");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string_view.pass.cpp
index 81ecca69fb3..0acf8286853 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/iter_iter_string_view.pass.cpp
@@ -264,7 +264,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 20, 0, SV("12345678901234567890"), S("abcdefghijklmnopqrst12345678901234567890"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -282,4 +282,6 @@ int main()
     test2<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_T_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_T_size_size.pass.cpp
index b320eff372c..2348747def0 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_T_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_T_size_size.pass.cpp
@@ -5869,7 +5869,7 @@ void test55()
     test_npos(S("abcdefghij"), 9, 2, SV("12345"), 6, S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -6025,4 +6025,6 @@ int main()
     s.replace(0, 4, arr, 0, std::string::npos);    // calls replace(pos1, n1, string("IJKL"), pos, npos)
     assert(s == "IJKL");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer.pass.cpp
index 6718242e0e8..a6a6c7d9dcf 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer.pass.cpp
@@ -363,7 +363,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 21, 0, "12345678901234567890", S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -379,4 +379,6 @@ int main()
     test2<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer_size.pass.cpp
index 53465bf680e..e3056670704 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_pointer_size.pass.cpp
@@ -1297,7 +1297,7 @@ void test11()
     test(S("abcdefghijklmnopqrst"), 21, 0, "12345678901234567890", 20, S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -1331,4 +1331,6 @@ int main()
     test11<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_size_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_size_char.pass.cpp
index 2e8c4527cc7..7d37e107561 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_size_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_size_char.pass.cpp
@@ -364,7 +364,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 21, 0, 20, '2', S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -380,4 +380,6 @@ int main()
     test2<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string.pass.cpp
index 85306d59595..c0fad33a398 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string.pass.cpp
@@ -362,7 +362,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 21, 0, S("12345678901234567890"), S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -387,4 +387,6 @@ int main()
     assert(s == "a");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_size_size.pass.cpp
index 7a75f03e59b..3fa32699fda 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_size_size.pass.cpp
@@ -5859,7 +5859,7 @@ void test55()
     test_npos(S("abcdefghij"), 9, 2, S("12345"), 6, S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -5981,4 +5981,6 @@ int main()
     test55<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_view.pass.cpp
index 9b35da025f9..542220aea70 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_replace/size_size_string_view.pass.cpp
@@ -362,7 +362,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 21, 0, SV("12345678901234567890"), S("can't happen"));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -380,4 +380,6 @@ int main()
     test2<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.modifiers/string_swap/swap.pass.cpp b/libcxx/test/std/strings/basic.string/string.modifiers/string_swap/swap.pass.cpp
index 79adee48764..8fdf3fea9b4 100644
--- a/libcxx/test/std/strings/basic.string/string.modifiers/string_swap/swap.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.modifiers/string_swap/swap.pass.cpp
@@ -31,7 +31,7 @@ test(S s1, S s2)
     assert(s2 == s1_);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -73,4 +73,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("12345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/nothing_to_do.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line.pass.cpp
index 9937863b28a..8e663cb4f60 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream in(" abc\n  def\n   ghij");
@@ -77,4 +77,6 @@ int main()
         assert(s == L"   ghij");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim.pass.cpp
index 965137c1d30..b081b55c920 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream in(" abc*  def**   ghij");
@@ -89,4 +89,6 @@ int main()
         assert(s == L"   ghij");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim_rv.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim_rv.pass.cpp
index b2255d068b2..b1511f21192 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim_rv.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_delim_rv.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("initial text");
@@ -45,4 +45,6 @@ int main()
         getline(std::wistringstream(L" abc*  def*   ghij"), s, L'*');
         assert(s == L" abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_rv.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_rv.pass.cpp
index a87529a0eab..cf4772c43d3 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_rv.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/get_line_rv.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::string s("initial text");
@@ -45,4 +45,6 @@ int main()
         getline(std::wistringstream(L" abc\n  def\n   ghij"), s);
         assert(s == L" abc");
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_extract.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_extract.pass.cpp
index 85f399dcd0d..389701d1d51 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_extract.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_extract.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::istringstream in("a bc defghij");
@@ -113,4 +113,6 @@ int main()
         assert(in.fail());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_insert.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_insert.pass.cpp
index eb272c29bc6..b30fd5afaf5 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_insert.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.io/stream_insert.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "min_allocator.h"
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream out;
@@ -87,4 +87,6 @@ int main()
         assert(L"   " + s == out.str());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap.pass.cpp
index 944bd455391..f644f287075 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap.pass.cpp
@@ -33,7 +33,7 @@ test(S s1, S s2)
     assert(s2 == s1_);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -75,4 +75,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("12345678901234567890"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp
index a00eb17be59..3f6ce447cf7 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string.special/swap_noexcept.pass.cpp
@@ -53,7 +53,7 @@ struct some_alloc2
     typedef std::true_type is_always_equal;
 };
 
-int main()
+int main(int, char**)
 {
     {
         typedef std::string C;
@@ -81,4 +81,6 @@ int main()
         static_assert( noexcept(swap(std::declval<C&>(), std::declval<C&>())), "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/pointer_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/pointer_string.pass.cpp
index 527d59d6887..bf2cc8413ab 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/pointer_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/pointer_string.pass.cpp
@@ -23,7 +23,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x)
     assert((lhs != rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_pointer.pass.cpp
index b1e6fa73d4f..76e0abe2378 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_pointer.pass.cpp
@@ -23,7 +23,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x)
     assert((lhs != rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string.pass.cpp
index 9825c1b3830..30aeb501a59 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string.pass.cpp
@@ -24,7 +24,7 @@ test(const S& lhs, const S& rhs, bool x)
     assert((lhs != rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string_view.pass.cpp
index 7108d819e0b..5b01455e7f8 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_string_view.pass.cpp
@@ -22,7 +22,7 @@ test(const S& lhs, SV rhs, bool x)
     assert((lhs != rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), SV("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_view_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_view_string.pass.cpp
index 8f3906bf18b..2d6957e3494 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_view_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op!=/string_view_string.pass.cpp
@@ -22,7 +22,7 @@ test(SV lhs, const S& rhs, bool x)
     assert((lhs != rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(SV("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/char_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/char_string.pass.cpp
index c24d8076842..9ab3c061197 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/char_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/char_string.pass.cpp
@@ -35,7 +35,7 @@ void test1(typename S::value_type lhs, S&& rhs, const S& x) {
 }
 #endif
 
-int main() {
+int main(int, char**) {
   {
     typedef std::string S;
     test0('a', S(""), S("a"));
@@ -66,4 +66,6 @@ int main() {
     test1('a', S("12345678901234567890"), S("a12345678901234567890"));
   }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/pointer_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/pointer_string.pass.cpp
index 654eca290f5..cf13fbb51d6 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/pointer_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/pointer_string.pass.cpp
@@ -35,7 +35,7 @@ void test1(const typename S::value_type* lhs, S&& rhs, const S& x) {
 }
 #endif
 
-int main() {
+int main(int, char**) {
   {
     typedef std::string S;
     test0("", S(""), S(""));
@@ -127,4 +127,6 @@ int main() {
           S("abcdefghijklmnopqrst12345678901234567890"));
   }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_char.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_char.pass.cpp
index 5196aba1a69..32411144db2 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_char.pass.cpp
@@ -35,7 +35,7 @@ void test1(S&& lhs, typename S::value_type rhs, const S& x) {
 }
 #endif
 
-int main() {
+int main(int, char**) {
   {
     typedef std::string S;
     test0(S(""), '1', S("1"));
@@ -66,4 +66,6 @@ int main() {
     test1(S("abcdefghijklmnopqrst"), '1', S("abcdefghijklmnopqrst1"));
   }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_pointer.pass.cpp
index ef8b8001009..4fec8482966 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_pointer.pass.cpp
@@ -35,7 +35,7 @@ void test1(S&& lhs, const typename S::value_type* rhs, const S& x) {
 }
 #endif
 
-int main() {
+int main(int, char**) {
   {
     typedef std::string S;
     test0(S(""), "", S(""));
@@ -126,4 +126,6 @@ int main() {
           S("abcdefghijklmnopqrst12345678901234567890"));
   }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_string.pass.cpp
index 2bc38c71a00..00aaf5cc092 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_op+/string_string.pass.cpp
@@ -58,7 +58,7 @@ void test3(S&& lhs, S&& rhs, const S& x) {
 
 #endif
 
-int main() {
+int main(int, char**) {
   {
     typedef std::string S;
     test0(S(""), S(""), S(""));
@@ -245,4 +245,6 @@ int main() {
           S("abcdefghijklmnopqrst12345678901234567890"));
   }
 #endif // TEST_STD_VER >= 11
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/pointer_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/pointer_string.pass.cpp
index 11ad5f15194..5db04b3a8d6 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/pointer_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/pointer_string.pass.cpp
@@ -23,7 +23,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x)
     assert((lhs == rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_pointer.pass.cpp
index f020c2234f3..aa79e17d121 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_pointer.pass.cpp
@@ -23,7 +23,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x)
     assert((lhs == rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string.pass.cpp
index 39ec5cc06e4..357a91fd9f5 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string.pass.cpp
@@ -24,7 +24,7 @@ test(const S& lhs, const S& rhs, bool x)
     assert((lhs == rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string_view.pass.cpp
index f4791e3b54c..06c16d07079 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_string_view.pass.cpp
@@ -22,7 +22,7 @@ test(const S& lhs, SV rhs, bool x)
     assert((lhs == rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), SV("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_view_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_view_string.pass.cpp
index fdf89a2c9c4..7ebdc093493 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_view_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_operator==/string_view_string.pass.cpp
@@ -22,7 +22,7 @@ test(SV lhs, const S& rhs, bool x)
     assert((lhs == rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(SV("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/pointer_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/pointer_string.pass.cpp
index dd27087b66c..db28cd4d1b4 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/pointer_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/pointer_string.pass.cpp
@@ -23,7 +23,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x)
     assert((lhs > rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_pointer.pass.cpp
index 4109eab3336..56521e91662 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_pointer.pass.cpp
@@ -23,7 +23,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x)
     assert((lhs > rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string.pass.cpp
index 3514ffc11bc..0cfafb80911 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string.pass.cpp
@@ -24,7 +24,7 @@ test(const S& lhs, const S& rhs, bool x)
     assert((lhs > rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string_view.pass.cpp
index 8ad82bf01f2..692fbd4fe81 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_string_view.pass.cpp
@@ -22,7 +22,7 @@ test(const S& lhs, SV rhs, bool x)
     assert((lhs > rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), SV("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_view_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_view_string.pass.cpp
index af98fa15363..f6a2fa55588 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_view_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt/string_view_string.pass.cpp
@@ -22,7 +22,7 @@ test(SV lhs, const S& rhs, bool x)
     assert((lhs > rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(SV("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/pointer_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/pointer_string.pass.cpp
index 0d7e5acea1c..e868531a683 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/pointer_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/pointer_string.pass.cpp
@@ -23,7 +23,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x)
     assert((lhs >= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_pointer.pass.cpp
index 93b9d2a874d..8aad5078247 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_pointer.pass.cpp
@@ -23,7 +23,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x)
     assert((lhs >= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string.pass.cpp
index 06f23205904..f0ab16cbb62 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string.pass.cpp
@@ -24,7 +24,7 @@ test(const S& lhs, const S& rhs, bool x)
     assert((lhs >= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string_view.pass.cpp
index 27c2b35d355..c7eb3e3e45e 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_string_view.pass.cpp
@@ -22,7 +22,7 @@ test(const S& lhs, SV rhs, bool x)
     assert((lhs >= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), SV("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_view_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_view_string.pass.cpp
index ff4a35b39bf..b49c1348a99 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_view_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_opgt=/string_view_string.pass.cpp
@@ -22,7 +22,7 @@ test(SV lhs, const S& rhs, bool x)
     assert((lhs >= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(SV("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/pointer_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/pointer_string.pass.cpp
index 0c3943d7db2..1609c4d87d9 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/pointer_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/pointer_string.pass.cpp
@@ -23,7 +23,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x)
     assert((lhs < rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_pointer.pass.cpp
index d91c3b1aeef..079344bb829 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_pointer.pass.cpp
@@ -23,7 +23,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x)
     assert((lhs < rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string.pass.cpp
index 0b05b6c3592..586faa40f07 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string.pass.cpp
@@ -24,7 +24,7 @@ test(const S& lhs, const S& rhs, bool x)
     assert((lhs < rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string_view.pass.cpp
index eec351c24ec..79393def5dd 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_string_view.pass.cpp
@@ -22,7 +22,7 @@ test(const S& lhs, SV rhs, bool x)
     assert((lhs < rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), SV("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_view_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_view_string.pass.cpp
index 9b2b7ddd9a3..7e8b139c332 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_view_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt/string_view_string.pass.cpp
@@ -22,7 +22,7 @@ test(SV lhs, const S& rhs, bool x)
     assert((lhs < rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(SV("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), false);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/pointer_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/pointer_string.pass.cpp
index 5354e6b75c4..cae9233dfb2 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/pointer_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/pointer_string.pass.cpp
@@ -23,7 +23,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x)
     assert((lhs <= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_pointer.pass.cpp
index 5fe8948dd61..07f9b355185 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_pointer.pass.cpp
@@ -23,7 +23,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x)
     assert((lhs <= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -65,4 +65,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string.pass.cpp
index 1261f518541..8d40f2f0a5b 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string.pass.cpp
@@ -24,7 +24,7 @@ test(const S& lhs, const S& rhs, bool x)
     assert((lhs <= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string_view.pass.cpp
index bdaa49a63a1..3df9e39cc0d 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_string_view.pass.cpp
@@ -22,7 +22,7 @@ test(const S& lhs, SV rhs, bool x)
     assert((lhs <= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), SV("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_view_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_view_string.pass.cpp
index 64d286cd890..cb7b1a4c451 100644
--- a/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_view_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.nonmembers/string_oplt=/string_view_string.pass.cpp
@@ -22,7 +22,7 @@ test(SV lhs, const S& rhs, bool x)
     assert((lhs <= rhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -66,4 +66,6 @@ int main()
     test(SV("abcdefghijklmnopqrst"), S("abcdefghijklmnopqrst"), true);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/nothing_to_do.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string.accessors/c_str.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string.accessors/c_str.pass.cpp
index 7c713e4b0b3..2677230c2d5 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string.accessors/c_str.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string.accessors/c_str.pass.cpp
@@ -30,7 +30,7 @@ test(const S& s)
         assert(T::eq(str[0], typename S::value_type()));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -48,4 +48,6 @@ int main()
     test(S("abcdefghijklmnopqrst"));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string.accessors/data.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string.accessors/data.pass.cpp
index 9c643a17236..6aa07302a95 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string.accessors/data.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string.accessors/data.pass.cpp
@@ -47,7 +47,7 @@ test_nonconst(S& s)
         assert(T::eq(str[0], typename S::value_type()));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -74,4 +74,6 @@ int main()
     S s4("abcdefghijklmnopqrst"); test_nonconst(s4);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string.accessors/get_allocator.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string.accessors/get_allocator.pass.cpp
index 6261ad55f1a..7edf5a88d9d 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string.accessors/get_allocator.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string.accessors/get_allocator.pass.cpp
@@ -23,7 +23,7 @@ test(const S& s, const typename S::allocator_type& a)
     assert(s.get_allocator() == a);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef test_allocator<char> A;
@@ -43,4 +43,6 @@ int main()
     test(S("abcdefghijklmnopqrst", A()), A());
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/pointer.pass.cpp
index 6219d6babfc..0af8ce02f95 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/pointer.pass.cpp
@@ -31,7 +31,7 @@ test(const S& s, const typename S::value_type* str, int x)
     assert(sign(s.compare(str)) == sign(x));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -73,4 +73,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_T_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_T_size_size.pass.cpp
index ad781f23c26..abab9879a14 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_T_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_T_size_size.pass.cpp
@@ -5840,7 +5840,7 @@ void test55()
     test_npos(S("abcde"), 0, 0, SV("abcdefghij"), 5, -5);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -5989,4 +5989,6 @@ int main()
 //  calls compare(size, size, string(arr), 0, npos)
     assert(s.compare(0, 4, arr, 0, std::string::npos) == 0);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer.pass.cpp
index aa44e16a9c3..4e77fc09c8e 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer.pass.cpp
@@ -361,7 +361,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 21, 0, "abcdefghijklmnopqrst", 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -377,4 +377,6 @@ int main()
     test2<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer_size.pass.cpp
index f9c0244ec3f..75efbadcc81 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_pointer_size.pass.cpp
@@ -1294,7 +1294,7 @@ void test11()
     test(S("abcdefghijklmnopqrst"), 21, 0, "abcdefghijklmnopqrst", 20, 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -1328,4 +1328,6 @@ int main()
     test11<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string.pass.cpp
index 06b5e531018..55fd823718e 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string.pass.cpp
@@ -360,7 +360,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 21, 0, S("abcdefghijklmnopqrst"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -383,4 +383,6 @@ int main()
     assert(s.compare(0, 1, {"abc", 1}) < 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_size_size.pass.cpp
index 6a231a867c3..05ba6ac82c5 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_size_size.pass.cpp
@@ -5836,7 +5836,7 @@ void test55()
     test_npos(S("abcde"), 0, 0, S("abcdefghij"), 5, -5);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -5958,4 +5958,6 @@ int main()
     test55<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_view.pass.cpp
index 00245e834d7..94c73ab31a6 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/size_size_string_view.pass.cpp
@@ -361,7 +361,7 @@ void test2()
     test(S("abcdefghijklmnopqrst"), 21, 0, SV("abcdefghijklmnopqrst"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -379,4 +379,6 @@ int main()
     test2<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/string.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/string.pass.cpp
index 7c3bdb1595e..279ae307584 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/string.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/string.pass.cpp
@@ -32,7 +32,7 @@ test(const S& s, const S& str, int x)
     assert(sign(s.compare(str)) == sign(x));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -81,4 +81,6 @@ int main()
     assert(s.compare({"abc", 1}) < 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_compare/string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_compare/string_view.pass.cpp
index 3e123ad7ace..2abc7fc1ac1 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_compare/string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_compare/string_view.pass.cpp
@@ -31,7 +31,7 @@ test(const S& s, SV sv, int x)
     assert(sign(s.compare(sv)) == sign(x));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -75,4 +75,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), SV("abcdefghijklmnopqrst"), 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/char_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/char_size.pass.cpp
index 2c4994670c8..7bada8446ff 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/char_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/char_size.pass.cpp
@@ -34,7 +34,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -98,4 +98,6 @@ int main()
     test(S("laenfsbridchgotmkqpj"), 'q', 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size.pass.cpp
index cb6fc1e9728..bd20ea1bb4a 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -154,4 +154,6 @@ int main()
     test1<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size_size.pass.cpp
index 708a04352f9..46c5511d9ae 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/pointer_size_size.pass.cpp
@@ -365,7 +365,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -383,4 +383,6 @@ int main()
     test3<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_size.pass.cpp
index 1ea41354f28..7f12ab1ba27 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -161,4 +161,6 @@ int main()
     assert(s.find_first_not_of({"abc", 1}) == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_view_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_view_size.pass.cpp
index 3cb3e74204d..54ce737ecc6 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.not.of/string_view_size.pass.cpp
@@ -139,7 +139,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), SV("htaobedqikfplcgjsmrn"), S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -155,4 +155,6 @@ int main()
     test1<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/char_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/char_size.pass.cpp
index cf8548744f8..da630f07e76 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/char_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/char_size.pass.cpp
@@ -34,7 +34,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -94,4 +94,6 @@ int main()
     test(S("laenfsbridchgotmkqpj"), 'e', 2);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size.pass.cpp
index 4c435537c46..2162ea14cf1 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -154,4 +154,6 @@ int main()
     test1<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size_size.pass.cpp
index c8b62b1f454..e0bb0f2fb77 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/pointer_size_size.pass.cpp
@@ -365,7 +365,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -383,4 +383,6 @@ int main()
     test3<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_size.pass.cpp
index fc79c89d151..1ae2123c3eb 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -161,4 +161,6 @@ int main()
     assert(s.find_first_of({"abc", 1}) == std::string::npos);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_view_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_view_size.pass.cpp
index ae29e47481b..8cd272408a0 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.first.of/string_view_size.pass.cpp
@@ -139,7 +139,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), SV("htaobedqikfplcgjsmrn"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -155,4 +155,6 @@ int main()
     test1<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/char_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/char_size.pass.cpp
index 6276c491075..fd77eb89d86 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/char_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/char_size.pass.cpp
@@ -34,7 +34,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -94,4 +94,6 @@ int main()
     test(S("laenfsbridchgotmkqpj"), 'i', 19);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size.pass.cpp
index 5cc9c0bf40a..1234ccb4de2 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -154,4 +154,6 @@ int main()
     test1<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size_size.pass.cpp
index 76834c2e81d..4c07f4d6129 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/pointer_size_size.pass.cpp
@@ -365,7 +365,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -383,4 +383,6 @@ int main()
     test3<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_size.pass.cpp
index 254e639dcfb..8232612c1e7 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -161,4 +161,6 @@ int main()
     assert(s.find_last_not_of({"abc", 1}) == s.size() - 1);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_view_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_view_size.pass.cpp
index 421ec966db2..da5054b7df6 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.not.of/string_view_size.pass.cpp
@@ -139,7 +139,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), SV("htaobedqikfplcgjsmrn"), S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -155,4 +155,6 @@ int main()
 //     test1<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/char_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/char_size.pass.cpp
index 2c5359e5edf..4292b1eb8bf 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/char_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/char_size.pass.cpp
@@ -34,7 +34,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -94,4 +94,6 @@ int main()
     test(S("laenfsbridchgotmkqpj"), 'm', 15);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size.pass.cpp
index 6a320788d4b..0b86a10c512 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", 19);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -154,4 +154,6 @@ int main()
     test1<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size_size.pass.cpp
index 46d61a44aec..9c5f670a9c7 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/pointer_size_size.pass.cpp
@@ -365,7 +365,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, 19);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -383,4 +383,6 @@ int main()
     test3<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_size.pass.cpp
index c5f1a3a7d96..f3ddb468d49 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), 19);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -161,4 +161,6 @@ int main()
     assert(s.find_last_of({"abc", 1}) == std::string::npos);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_view_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_view_size.pass.cpp
index f98d66eec45..ccf181faa55 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find.last.of/string_view_size.pass.cpp
@@ -139,7 +139,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), SV("htaobedqikfplcgjsmrn"), 19);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -155,4 +155,6 @@ int main()
     test1<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find/char_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find/char_size.pass.cpp
index c346a0196f3..5700d09575f 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find/char_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find/char_size.pass.cpp
@@ -34,7 +34,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(0 <= x && x + 1 <= s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -94,4 +94,6 @@ int main()
     test(S("abcdeabcdeabcdeabcde"), 'c', 2);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size.pass.cpp
index a6136d3f844..6e7ae3d41f4 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size.pass.cpp
@@ -146,7 +146,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -160,4 +160,6 @@ int main()
     test1<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size_size.pass.cpp
index 176ffbb563a..fad7507173d 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find/pointer_size_size.pass.cpp
@@ -365,7 +365,7 @@ void test3()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -383,4 +383,6 @@ int main()
     test3<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find/string_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find/string_size.pass.cpp
index 482648ab3b0..e8a91dd1f67 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find/string_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find/string_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), S("abcdeabcdeabcdeabcde"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -161,4 +161,6 @@ int main()
     assert(s.find({"abc", 1}) == std::string::npos);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_find/string_view_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_find/string_view_size.pass.cpp
index d84a41e4ca8..c1e78af1025 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_find/string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_find/string_view_size.pass.cpp
@@ -139,7 +139,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), SV("abcdeabcdeabcdeabcde"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -155,4 +155,6 @@ int main()
     test1<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/char_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/char_size.pass.cpp
index 9a30a63d172..46ced312391 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/char_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/char_size.pass.cpp
@@ -34,7 +34,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x + 1 <= s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -94,4 +94,6 @@ int main()
     test(S("abcdeabcdeabcdeabcde"), 'b', 16);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size.pass.cpp
index 57a4d06bd13..715b5e57855 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size.pass.cpp
@@ -147,7 +147,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -161,4 +161,6 @@ int main()
     test1<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size_size.pass.cpp
index 786affd27bc..e9670095227 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/pointer_size_size.pass.cpp
@@ -365,7 +365,7 @@ void test3()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 21, 20, 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -383,4 +383,6 @@ int main()
     test3<S>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_size.pass.cpp
index c83acbf4d5d..74cfb02ee28 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), S("abcdeabcdeabcdeabcde"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -161,4 +161,6 @@ int main()
     assert(s.rfind({"abc", 1}) == std::string::npos);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_view_size.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_view_size.pass.cpp
index 3657e028c2e..ea4f9c20597 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_rfind/string_view_size.pass.cpp
@@ -139,7 +139,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), SV("abcdeabcdeabcdeabcde"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -155,4 +155,6 @@ int main()
     test1<S, SV>();
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.ops/string_substr/substr.pass.cpp b/libcxx/test/std/strings/basic.string/string.ops/string_substr/substr.pass.cpp
index 767dc506339..27af66e0670 100644
--- a/libcxx/test/std/strings/basic.string/string.ops/string_substr/substr.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.ops/string_substr/substr.pass.cpp
@@ -47,7 +47,7 @@ test(const S& s, typename S::size_type pos, typename S::size_type n)
 #endif
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -173,4 +173,6 @@ int main()
     test(S("dplqartnfgejichmoskb"), 21, 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp b/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp
index fb2e3e6ce6b..be090c90e17 100644
--- a/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.require/contiguous.pass.cpp
@@ -24,7 +24,7 @@ void test_contiguous ( const C &c )
         assert ( *(c.begin() + static_cast<typename C::difference_type>(i)) == *(std::addressof(*c.begin()) + i));
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -49,4 +49,6 @@ int main()
     test_contiguous(S("1234567890123456789012345678901234567890123456789012345678901234567890", A()));
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp
index bc9fb26a5d2..8eae5f7c86c 100644
--- a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.char.pass.cpp
@@ -16,7 +16,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -30,4 +30,6 @@ int main()
     assert ( s2.starts_with('a'));
     assert (!s2.starts_with('x'));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp
index ff46fc33d91..412ed574c78 100644
--- a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.ptr.pass.cpp
@@ -16,7 +16,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -58,4 +58,6 @@ int main()
     assert (!sNot.starts_with("abcde"));
     assert ( sNot.starts_with("def"));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp
index acb90a0c8b1..c951b4c7374 100644
--- a/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/string.starts_with/starts_with.string_view.pass.cpp
@@ -16,7 +16,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string S;
@@ -68,4 +68,6 @@ int main()
     assert (!sNot.starts_with(sv5));
     assert ( sNot.starts_with(svNot));
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/traits_mismatch.fail.cpp b/libcxx/test/std/strings/basic.string/traits_mismatch.fail.cpp
index 7e57ae1a7b1..47524d2c34d 100644
--- a/libcxx/test/std/strings/basic.string/traits_mismatch.fail.cpp
+++ b/libcxx/test/std/strings/basic.string/traits_mismatch.fail.cpp
@@ -11,7 +11,9 @@
 
 #include <string>
 
-int main()
+int main(int, char**)
 {
     std::basic_string<char, std::char_traits<wchar_t>> s;
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/basic.string/types.pass.cpp b/libcxx/test/std/strings/basic.string/types.pass.cpp
index 0d074fe05fb..5aa2c7cf8be 100644
--- a/libcxx/test/std/strings/basic.string/types.pass.cpp
+++ b/libcxx/test/std/strings/basic.string/types.pass.cpp
@@ -70,7 +70,7 @@ test()
     static_assert(S::npos == -1, "");
 }
 
-int main()
+int main(int, char**)
 {
     test<test_traits<char>, test_allocator<char> >();
     test<std::char_traits<wchar_t>, std::allocator<wchar_t> >();
@@ -81,4 +81,6 @@ int main()
 #if TEST_STD_VER >= 11
     test<std::char_traits<char>, min_allocator<char> >();
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/c.strings/cctype.pass.cpp b/libcxx/test/std/strings/c.strings/cctype.pass.cpp
index feb5c29d22f..c26c1e6a20f 100644
--- a/libcxx/test/std/strings/c.strings/cctype.pass.cpp
+++ b/libcxx/test/std/strings/c.strings/cctype.pass.cpp
@@ -70,7 +70,7 @@
 #error toupper defined
 #endif
 
-int main()
+int main(int, char**)
 {
 
     ASSERT_SAME_TYPE(int, decltype(std::isalnum(0)));
@@ -102,4 +102,6 @@ int main()
     assert( std::isxdigit('a'));
     assert( std::tolower('A') == 'a');
     assert( std::toupper('a') == 'A');
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/c.strings/cstring.pass.cpp b/libcxx/test/std/strings/c.strings/cstring.pass.cpp
index c61f5c4ff8a..c8ee2789df4 100644
--- a/libcxx/test/std/strings/c.strings/cstring.pass.cpp
+++ b/libcxx/test/std/strings/c.strings/cstring.pass.cpp
@@ -17,7 +17,7 @@
 #error NULL not defined
 #endif
 
-int main()
+int main(int, char**)
 {
     std::size_t s = 0;
     void* vp = 0;
@@ -60,4 +60,6 @@ int main()
     ASSERT_SAME_TYPE(const char*, decltype(std::strrchr(cpc, 0)));
     ASSERT_SAME_TYPE(const char*, decltype(std::strstr(cpc, cpc)));
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/c.strings/cuchar.pass.cpp b/libcxx/test/std/strings/c.strings/cuchar.pass.cpp
index 989ca6b0427..4271503d4e2 100644
--- a/libcxx/test/std/strings/c.strings/cuchar.pass.cpp
+++ b/libcxx/test/std/strings/c.strings/cuchar.pass.cpp
@@ -14,6 +14,8 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/c.strings/cwchar.pass.cpp b/libcxx/test/std/strings/c.strings/cwchar.pass.cpp
index c7558859e1b..667910bc1a1 100644
--- a/libcxx/test/std/strings/c.strings/cwchar.pass.cpp
+++ b/libcxx/test/std/strings/c.strings/cwchar.pass.cpp
@@ -31,7 +31,7 @@
 #error WEOF not defined
 #endif
 
-int main()
+int main(int, char**)
 {
     std::mbstate_t mb = {};
     std::size_t s = 0;
@@ -128,4 +128,6 @@ int main()
     ASSERT_SAME_TYPE(int,                decltype(std::vwprintf(L"", va)));
     ASSERT_SAME_TYPE(int,                decltype(std::wprintf(L"")));
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/c.strings/cwctype.pass.cpp b/libcxx/test/std/strings/c.strings/cwctype.pass.cpp
index a7d9560d71e..3bcda1a472c 100644
--- a/libcxx/test/std/strings/c.strings/cwctype.pass.cpp
+++ b/libcxx/test/std/strings/c.strings/cwctype.pass.cpp
@@ -90,7 +90,7 @@
 #error wctrans defined
 #endif
 
-int main()
+int main(int, char**)
 {
     std::wint_t w = 0;
     ASSERT_SAME_TYPE(int, decltype(std::iswalnum(w)));
@@ -113,4 +113,6 @@ int main()
     ASSERT_SAME_TYPE(std::wint_t,    decltype(std::towupper(w)));
     ASSERT_SAME_TYPE(std::wint_t,    decltype(std::towctrans(w, std::wctrans_t())));
     ASSERT_SAME_TYPE(std::wctrans_t, decltype(std::wctrans("")));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.require/nothing_to_do.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.require/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.require/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.require/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp
index 8f80a53ed70..c60e6db9fc4 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign2.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     char c = '\0';
     std::char_traits<char>::assign(c, 'a');
@@ -36,4 +36,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign3.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign3.pass.cpp
index 74e0f907672..e2cbe3d5dbe 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign3.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/assign3.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     char s2[3] = {0};
     assert(std::char_traits<char>::assign(s2, 3, char(5)) == s2);
@@ -23,4 +23,6 @@ int main()
     assert(s2[1] == char(5));
     assert(s2[2] == char(5));
     assert(std::char_traits<char>::assign(NULL, 0, char(5)) == NULL);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
index 637095127bc..4926b6296e7 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/compare.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char>::compare("", "", 0) == 0);
     assert(std::char_traits<char>::compare(NULL, NULL, 0) == 0);
@@ -53,4 +53,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp
index bd12bfd21e4..3a8e3bda6bc 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/copy.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     char s1[] = {1, 2, 3};
     char s2[3] = {0};
@@ -25,4 +25,6 @@ int main()
     assert(s2[2] == char(3));
     assert(std::char_traits<char>::copy(NULL, s1, 0) == NULL);
     assert(std::char_traits<char>::copy(s1, NULL, 0) == s1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eof.pass.cpp
index ad99e30b24e..0ea0995da1f 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eof.pass.cpp
@@ -15,7 +15,9 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char>::eof() == EOF);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq.pass.cpp
index 7895baf9975..f0cef792d14 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq.pass.cpp
@@ -15,8 +15,10 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char>::eq('a', 'a'));
     assert(!std::char_traits<char>::eq('a', 'A'));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq_int_type.pass.cpp
index ca6808f865c..0fbb4389c60 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/eq_int_type.pass.cpp
@@ -15,11 +15,13 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert( std::char_traits<char>::eq_int_type('a', 'a'));
     assert(!std::char_traits<char>::eq_int_type('a', 'A'));
     assert(!std::char_traits<char>::eq_int_type(std::char_traits<char>::eof(), 'A'));
     assert( std::char_traits<char>::eq_int_type(std::char_traits<char>::eof(),
                                                 std::char_traits<char>::eof()));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp
index 242d3a17392..97450084080 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/find.pass.cpp
@@ -29,7 +29,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     char s1[] = {1, 2, 3};
     assert(std::char_traits<char>::find(s1, 3, char(1)) == s1);
@@ -42,4 +42,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
index f556c952eac..8be4e0a7055 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/length.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 #endif
 
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char>::length("") == 0);
     assert(std::char_traits<char>::length("a") == 1);
@@ -38,4 +38,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/lt.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/lt.pass.cpp
index 497679636ec..e62090cf4c4 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/lt.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/lt.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert( std::char_traits<char>::lt('\0', 'A'));
     assert(!std::char_traits<char>::lt('A', '\0'));
@@ -29,4 +29,6 @@ int main()
 
     assert( std::char_traits<char>::lt(' ', 'A'));
     assert( std::char_traits<char>::lt('A', '~'));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/move.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/move.pass.cpp
index c1f885939ba..ecbb61901a9 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/move.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/move.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     char s1[] = {1, 2, 3};
     assert(std::char_traits<char>::move(s1, s1+1, 2) == s1);
@@ -29,4 +29,6 @@ int main()
     assert(s1[2] == char(3));
     assert(std::char_traits<char>::move(NULL, s1, 0) == NULL);
     assert(std::char_traits<char>::move(s1, NULL, 0) == s1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/not_eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/not_eof.pass.cpp
index 01568e5a428..1c37a7c2efb 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/not_eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/not_eof.pass.cpp
@@ -15,11 +15,13 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char>::not_eof('a') == 'a');
     assert(std::char_traits<char>::not_eof('A') == 'A');
     assert(std::char_traits<char>::not_eof(0) == 0);
     assert(std::char_traits<char>::not_eof(std::char_traits<char>::eof()) !=
            std::char_traits<char>::eof());
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_char_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_char_type.pass.cpp
index fbf8f2f584b..d8a957016f9 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_char_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_char_type.pass.cpp
@@ -15,9 +15,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char>::to_char_type('a') == 'a');
     assert(std::char_traits<char>::to_char_type('A') == 'A');
     assert(std::char_traits<char>::to_char_type(0) == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_int_type.pass.cpp
index eb8df3b6913..dd903f9e6c0 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/to_int_type.pass.cpp
@@ -15,9 +15,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char>::to_int_type('a') == 'a');
     assert(std::char_traits<char>::to_int_type('A') == 'A');
     assert(std::char_traits<char>::to_int_type(0) == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/types.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/types.pass.cpp
index 6439c1ea07e..30d31ebc920 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/types.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char/types.pass.cpp
@@ -19,11 +19,13 @@
 #include <string>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::char_traits<char>::char_type, char>::value), "");
     static_assert((std::is_same<std::char_traits<char>::int_type, int>::value), "");
     static_assert((std::is_same<std::char_traits<char>::off_type, std::streamoff>::value), "");
     static_assert((std::is_same<std::char_traits<char>::pos_type, std::streampos>::value), "");
     static_assert((std::is_same<std::char_traits<char>::state_type, std::mbstate_t>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
index 77b8687e8c6..017d0e7acce 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign2.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -40,4 +40,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign3.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign3.pass.cpp
index c623baa248c..8838b81e14b 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign3.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/assign3.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char16_t s2[3] = {0};
@@ -25,4 +25,6 @@ int main()
     assert(s2[2] == char16_t(5));
     assert(std::char_traits<char16_t>::assign(NULL, 0, char16_t(5)) == NULL);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp
index 2e3b18aca07..d0782c09338 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/compare.pass.cpp
@@ -28,7 +28,7 @@ constexpr bool test_constexpr()
 #endif
 
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -58,4 +58,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp
index 0bf5d47eeb5..102f15acdee 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/copy.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char16_t s1[] = {1, 2, 3};
@@ -27,4 +27,6 @@ int main()
     assert(std::char_traits<char16_t>::copy(NULL, s1, 0) == NULL);
     assert(std::char_traits<char16_t>::copy(s1, NULL, 0) == s1);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eof.pass.cpp
index bb0a4506a9a..c80b0792a49 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eof.pass.cpp
@@ -15,10 +15,12 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     std::char_traits<char16_t>::int_type i = std::char_traits<char16_t>::eof();
     ((void)i); // Prevent unused warning
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq.pass.cpp
index f4abe84dbd6..1c705109f28 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -25,4 +25,6 @@ int main()
     assert(!std::char_traits<char16_t>::eq(u'a', u'A'));
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq_int_type.pass.cpp
index 9a24cf13d0c..bef97d612eb 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/eq_int_type.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -28,4 +28,6 @@ int main()
     assert( std::char_traits<char16_t>::eq_int_type(std::char_traits<char16_t>::eof(),
                                                     std::char_traits<char16_t>::eof()));
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp
index cd31e5925de..2ca7e534327 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/find.pass.cpp
@@ -29,7 +29,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char16_t s1[] = {1, 2, 3};
@@ -44,4 +44,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp
index 2a2a35702fc..f487c410b0b 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/length.pass.cpp
@@ -26,7 +26,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -41,4 +41,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/lt.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/lt.pass.cpp
index 4ade9b6f06d..a43a9e45cc2 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/lt.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/lt.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -25,4 +25,6 @@ int main()
     assert( std::char_traits<char16_t>::lt(u'A', u'a'));
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/move.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/move.pass.cpp
index ddf07a022c9..aa55e0d11ce 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/move.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/move.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char16_t s1[] = {1, 2, 3};
@@ -31,4 +31,6 @@ int main()
     assert(std::char_traits<char16_t>::move(NULL, s1, 0) == NULL);
     assert(std::char_traits<char16_t>::move(s1, NULL, 0) == s1);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/not_eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/not_eof.pass.cpp
index ea6f0ab17cd..bf26b4cf330 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/not_eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/not_eof.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -28,4 +28,6 @@ int main()
     assert(std::char_traits<char16_t>::not_eof(std::char_traits<char16_t>::eof()) !=
            std::char_traits<char16_t>::eof());
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_char_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_char_type.pass.cpp
index 9256a528172..738754bf983 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_char_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_char_type.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -26,4 +26,6 @@ int main()
 #endif
     assert(std::char_traits<char16_t>::to_char_type(0) == 0);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_int_type.pass.cpp
index 411f5202b11..83fff60b886 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/to_int_type.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -26,4 +26,6 @@ int main()
 #endif
     assert(std::char_traits<char16_t>::to_int_type(0) == 0);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/types.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/types.pass.cpp
index ae8792c4901..41e3fd4d57b 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/types.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char16_t/types.pass.cpp
@@ -20,7 +20,7 @@
 #include <type_traits>
 #include <cstdint>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     static_assert((std::is_same<std::char_traits<char16_t>::char_type, char16_t>::value), "");
@@ -29,4 +29,6 @@ int main()
     static_assert((std::is_same<std::char_traits<char16_t>::pos_type, std::u16streampos>::value), "");
     static_assert((std::is_same<std::char_traits<char16_t>::state_type, std::mbstate_t>::value), "");
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp
index 90388aa43f8..f77d54f7916 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign2.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -40,4 +40,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign3.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign3.pass.cpp
index af69fdcfa2a..26985481c1f 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign3.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/assign3.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char32_t s2[3] = {0};
@@ -25,4 +25,6 @@ int main()
     assert(s2[2] == char32_t(5));
     assert(std::char_traits<char32_t>::assign(NULL, 0, char32_t(5)) == NULL);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp
index 5d1cfa84248..f2dd01ac9aa 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/compare.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -57,4 +57,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp
index d9f983b5bd6..8b2d6ce9074 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/copy.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char32_t s1[] = {1, 2, 3};
@@ -27,4 +27,6 @@ int main()
     assert(std::char_traits<char32_t>::copy(NULL, s1, 0) == NULL);
     assert(std::char_traits<char32_t>::copy(s1, NULL, 0) == s1);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eof.pass.cpp
index ac042907ab8..5c28f47bb48 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eof.pass.cpp
@@ -15,10 +15,12 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     std::char_traits<char32_t>::int_type i = std::char_traits<char32_t>::eof();
     ((void)i); // Prevent unused warning
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq.pass.cpp
index aef7ebb703d..516f38bd087 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -25,4 +25,6 @@ int main()
     assert(!std::char_traits<char32_t>::eq(U'a', U'A'));
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq_int_type.pass.cpp
index 91b2fb0fbad..5d241159f72 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/eq_int_type.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -28,4 +28,6 @@ int main()
     assert( std::char_traits<char32_t>::eq_int_type(std::char_traits<char32_t>::eof(),
                                                     std::char_traits<char32_t>::eof()));
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp
index ac1723a6535..5a89596dee9 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/find.pass.cpp
@@ -29,7 +29,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char32_t s1[] = {1, 2, 3};
@@ -44,4 +44,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp
index c4c01ddf1a4..ef2ea3419bd 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/length.pass.cpp
@@ -26,7 +26,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -41,4 +41,6 @@ int main()
     static_assert(test_constexpr(), "" );
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/lt.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/lt.pass.cpp
index d3fe9a4516e..51c1faf9ef2 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/lt.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/lt.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -25,4 +25,6 @@ int main()
     assert( std::char_traits<char32_t>::lt(U'A', U'a'));
 #endif
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/move.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/move.pass.cpp
index 0ac49d0c9c3..7cda99bd830 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/move.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/move.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     char32_t s1[] = {1, 2, 3};
@@ -31,4 +31,6 @@ int main()
     assert(std::char_traits<char32_t>::move(NULL, s1, 0) == NULL);
     assert(std::char_traits<char32_t>::move(s1, NULL, 0) == s1);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/not_eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/not_eof.pass.cpp
index dbe1dfe8b30..aeba1228e6f 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/not_eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/not_eof.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -28,4 +28,6 @@ int main()
     assert(std::char_traits<char32_t>::not_eof(std::char_traits<char32_t>::eof()) !=
            std::char_traits<char32_t>::eof());
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_char_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_char_type.pass.cpp
index 1c16a55b811..75104e7bf16 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_char_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_char_type.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -26,4 +26,6 @@ int main()
 #endif
     assert(std::char_traits<char32_t>::to_char_type(0) == 0);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_int_type.pass.cpp
index 4ec9a9b631f..8299e94dabd 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/to_int_type.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
 #if TEST_STD_VER >= 11
@@ -26,4 +26,6 @@ int main()
 #endif
     assert(std::char_traits<char32_t>::to_int_type(0) == 0);
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/types.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/types.pass.cpp
index 65624dd5efd..5ec558f5470 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/types.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char32_t/types.pass.cpp
@@ -20,7 +20,7 @@
 #include <type_traits>
 #include <cstdint>
 
-int main()
+int main(int, char**)
 {
 #ifndef _LIBCPP_HAS_NO_UNICODE_CHARS
     static_assert((std::is_same<std::char_traits<char32_t>::char_type, char32_t>::value), "");
@@ -29,4 +29,6 @@ int main()
     static_assert((std::is_same<std::char_traits<char32_t>::pos_type, std::u32streampos>::value), "");
     static_assert((std::is_same<std::char_traits<char32_t>::state_type, std::mbstate_t>::value), "");
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign2.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign2.pass.cpp
index b14662d09be..c669ab9c1a6 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign2.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign2.pass.cpp
@@ -25,7 +25,7 @@ constexpr bool test_constexpr()
     return c == u'a';
 }
 
-int main()
+int main(int, char**)
 {
     char8_t c = u8'\0';
     std::char_traits<char8_t>::assign(c, u8'a');
@@ -34,5 +34,7 @@ int main()
     static_assert(test_constexpr(), "");
 }
 #else
-int main () {}
+int main(int, char**) {
+  return 0;
+}
 #endif
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign3.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign3.pass.cpp
index eae7c82ba86..f9c176e9b2f 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign3.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/assign3.pass.cpp
@@ -16,7 +16,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     char8_t s2[3] = {0};
@@ -26,4 +26,6 @@ int main()
     assert(s2[2] == char8_t(5));
     assert(std::char_traits<char8_t>::assign(NULL, 0, char8_t(5)) == NULL);
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp
index 0ac815b9b17..063ab5dc516 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/compare.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char8_t>::compare(u8"", u8"", 0) == 0);
     assert(std::char_traits<char8_t>::compare(NULL, NULL, 0) == 0);
@@ -53,5 +53,7 @@ int main()
     static_assert(test_constexpr(), "" );
 }
 #else
-int main () {}
+int main(int, char**) {
+  return 0;
+}
 #endif
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp
index 2f091029b06..7bf949197a8 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/copy.pass.cpp
@@ -16,7 +16,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     char8_t s1[] = {1, 2, 3};
@@ -28,4 +28,6 @@ int main()
     assert(std::char_traits<char8_t>::copy(NULL, s1, 0) == NULL);
     assert(std::char_traits<char8_t>::copy(s1, NULL, 0) == s1);
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eof.pass.cpp
index 9d13d7dd0a6..e112556886d 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eof.pass.cpp
@@ -16,10 +16,12 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     std::char_traits<char8_t>::int_type i = std::char_traits<char8_t>::eof();
     ((void)i); // Prevent unused warning
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq.pass.cpp
index 4d334110f36..6e32c85bbe3 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq.pass.cpp
@@ -18,10 +18,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     assert( std::char_traits<char8_t>::eq(u8'a', u8'a'));
     assert(!std::char_traits<char8_t>::eq(u8'a', u8'A'));
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq_int_type.pass.cpp
index 6cc58eba1db..8c5e1971747 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/eq_int_type.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     assert( std::char_traits<char8_t>::eq_int_type(u8'a', u8'a'));
@@ -27,4 +27,6 @@ int main()
     assert( std::char_traits<char8_t>::eq_int_type(std::char_traits<char8_t>::eof(),
                                                     std::char_traits<char8_t>::eof()));
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/find.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/find.pass.cpp
index 9d2e62e348c..170539e0694 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/find.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/find.pass.cpp
@@ -28,7 +28,7 @@ constexpr bool test_constexpr()
         && std::char_traits<char8_t>::find(p, 3, u8'4') == nullptr;
 }
 
-int main()
+int main(int, char**)
 {
     char8_t s1[] = {1, 2, 3};
     assert(std::char_traits<char8_t>::find(s1, 3, char8_t(1)) == s1);
@@ -41,5 +41,7 @@ int main()
     static_assert(test_constexpr(), "" );
 }
 #else
-int main () {}
+int main(int, char**) {
+  return 0;
+}
 #endif
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/length.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/length.pass.cpp
index 10f800127b6..ce2c717cc57 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/length.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/length.pass.cpp
@@ -25,7 +25,7 @@ constexpr bool test_constexpr()
         && std::char_traits<char8_t>::length(u8"abcd") == 4;
 }
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<char8_t>::length(u8"") == 0);
     assert(std::char_traits<char8_t>::length(u8"a") == 1);
@@ -36,5 +36,7 @@ int main()
     static_assert(test_constexpr(), "");
 }
 #else
-int main() { }
+int main(int, char**) { 
+  return 0;
+}
 #endif
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/lt.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/lt.pass.cpp
index 4653007bf72..a4fb1251203 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/lt.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/lt.pass.cpp
@@ -18,10 +18,12 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     assert(!std::char_traits<char8_t>::lt(u8'a', u8'a'));
     assert( std::char_traits<char8_t>::lt(u8'A', u8'a'));
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/move.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/move.pass.cpp
index 5ca536966cd..a5e1359dd4d 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/move.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/move.pass.cpp
@@ -16,7 +16,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     char8_t s1[] = {1, 2, 3};
@@ -32,4 +32,6 @@ int main()
     assert(std::char_traits<char8_t>::move(NULL, s1, 0) == NULL);
     assert(std::char_traits<char8_t>::move(s1, NULL, 0) == s1);
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/not_eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/not_eof.pass.cpp
index 69e8ddac8cc..3d1141d72d7 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/not_eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/not_eof.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     assert(std::char_traits<char8_t>::not_eof(u8'a') == u8'a');
@@ -27,4 +27,6 @@ int main()
     assert(std::char_traits<char8_t>::not_eof(std::char_traits<char8_t>::eof()) !=
            std::char_traits<char8_t>::eof());
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_char_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_char_type.pass.cpp
index 0b021d28340..4edc49452ef 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_char_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_char_type.pass.cpp
@@ -18,11 +18,13 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     assert(std::char_traits<char8_t>::to_char_type(u8'a') == u8'a');
     assert(std::char_traits<char8_t>::to_char_type(u8'A') == u8'A');
     assert(std::char_traits<char8_t>::to_char_type(0) == 0);
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_int_type.pass.cpp
index 98974ab86b1..ab3c9dc7993 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/to_int_type.pass.cpp
@@ -18,11 +18,13 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     assert(std::char_traits<char8_t>::to_int_type(u8'a') == u8'a');
     assert(std::char_traits<char8_t>::to_int_type(u8'A') == u8'A');
     assert(std::char_traits<char8_t>::to_int_type(0) == 0);
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/types.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/types.pass.cpp
index cfb20faaf75..245dcd87d99 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/types.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.char8_t/types.pass.cpp
@@ -21,7 +21,7 @@
 #include <type_traits>
 #include <cstdint>
 
-int main()
+int main(int, char**)
 {
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     static_assert((std::is_same<std::char_traits<char8_t>::char_type,  char8_t>::value), "");
@@ -30,4 +30,6 @@ int main()
     static_assert((std::is_same<std::char_traits<char8_t>::pos_type,   std::u16streampos>::value), "");
     static_assert((std::is_same<std::char_traits<char8_t>::state_type, std::mbstate_t>::value), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp
index 9b9b0ea491c..25e42701448 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign2.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     wchar_t c = L'\0';
     std::char_traits<wchar_t>::assign(c, L'a');
@@ -36,4 +36,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign3.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign3.pass.cpp
index 42df4081d50..d4ed4340945 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign3.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/assign3.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     wchar_t s2[3] = {0};
     assert(std::char_traits<wchar_t>::assign(s2, 3, wchar_t(5)) == s2);
@@ -23,4 +23,6 @@ int main()
     assert(s2[1] == wchar_t(5));
     assert(s2[2] == wchar_t(5));
     assert(std::char_traits<wchar_t>::assign(NULL, 0, wchar_t(5)) == NULL);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp
index d6272f39357..1c2e11912f8 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/compare.pass.cpp
@@ -27,7 +27,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<wchar_t>::compare(L"", L"", 0) == 0);
     assert(std::char_traits<wchar_t>::compare(NULL, NULL, 0) == 0);
@@ -53,4 +53,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp
index f90688a9aac..309c21316c4 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/copy.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     wchar_t s1[] = {1, 2, 3};
     wchar_t s2[3] = {0};
@@ -25,4 +25,6 @@ int main()
     assert(s2[2] == wchar_t(3));
     assert(std::char_traits<wchar_t>::copy(NULL, s1, 0) == NULL);
     assert(std::char_traits<wchar_t>::copy(s1, NULL, 0) == s1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eof.pass.cpp
index 9b466a5f0cc..6190220fe90 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eof.pass.cpp
@@ -15,7 +15,9 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<wchar_t>::eof() == WEOF);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq.pass.cpp
index a89a0002da7..701a6502fc6 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq.pass.cpp
@@ -15,8 +15,10 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<wchar_t>::eq(L'a', L'a'));
     assert(!std::char_traits<wchar_t>::eq(L'a', L'A'));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq_int_type.pass.cpp
index e7e8285ca0f..b218186b43f 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/eq_int_type.pass.cpp
@@ -15,11 +15,13 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert( std::char_traits<wchar_t>::eq_int_type(L'a', L'a'));
     assert(!std::char_traits<wchar_t>::eq_int_type(L'a', L'A'));
     assert(!std::char_traits<wchar_t>::eq_int_type(std::char_traits<wchar_t>::eof(), L'A'));
     assert( std::char_traits<wchar_t>::eq_int_type(std::char_traits<wchar_t>::eof(),
                                                    std::char_traits<wchar_t>::eof()));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp
index ed59397cc2c..78a9ad5c3f9 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/find.pass.cpp
@@ -29,7 +29,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     wchar_t s1[] = {1, 2, 3};
     assert(std::char_traits<wchar_t>::find(s1, 3, wchar_t(1)) == s1);
@@ -42,4 +42,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
index a9176c8d459..742189205ab 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/length.pass.cpp
@@ -26,7 +26,7 @@ constexpr bool test_constexpr()
 }
 #endif
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<wchar_t>::length(L"") == 0);
     assert(std::char_traits<wchar_t>::length(L"a") == 1);
@@ -37,4 +37,6 @@ int main()
 #if TEST_STD_VER > 14
     static_assert(test_constexpr(), "" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/lt.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/lt.pass.cpp
index f7950b782bb..9abd9cf59d7 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/lt.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/lt.pass.cpp
@@ -15,8 +15,10 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(!std::char_traits<wchar_t>::lt(L'a', L'a'));
     assert( std::char_traits<wchar_t>::lt(L'A', L'a'));
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/move.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/move.pass.cpp
index d833bc0b5b2..341a90233a8 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/move.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/move.pass.cpp
@@ -15,7 +15,7 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     wchar_t s1[] = {1, 2, 3};
     assert(std::char_traits<wchar_t>::move(s1, s1+1, 2) == s1);
@@ -29,4 +29,6 @@ int main()
     assert(s1[2] == wchar_t(3));
     assert(std::char_traits<wchar_t>::move(NULL, s1, 0) == NULL);
     assert(std::char_traits<wchar_t>::move(s1, NULL, 0) == s1);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/not_eof.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/not_eof.pass.cpp
index 751903beae4..92f08b1d520 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/not_eof.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/not_eof.pass.cpp
@@ -15,11 +15,13 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<wchar_t>::not_eof(L'a') == L'a');
     assert(std::char_traits<wchar_t>::not_eof(L'A') == L'A');
     assert(std::char_traits<wchar_t>::not_eof(0) == 0);
     assert(std::char_traits<wchar_t>::not_eof(std::char_traits<wchar_t>::eof()) !=
            std::char_traits<wchar_t>::eof());
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_char_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_char_type.pass.cpp
index 7654c32873f..f479bec9daf 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_char_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_char_type.pass.cpp
@@ -15,9 +15,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<wchar_t>::to_char_type(L'a') == L'a');
     assert(std::char_traits<wchar_t>::to_char_type(L'A') == L'A');
     assert(std::char_traits<wchar_t>::to_char_type(0) == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_int_type.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_int_type.pass.cpp
index a003bdc1115..11fe2419b1a 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_int_type.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/to_int_type.pass.cpp
@@ -15,9 +15,11 @@
 #include <string>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     assert(std::char_traits<wchar_t>::to_int_type(L'a') == L'a');
     assert(std::char_traits<wchar_t>::to_int_type(L'A') == L'A');
     assert(std::char_traits<wchar_t>::to_int_type(0) == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/types.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/types.pass.cpp
index c367be47ef3..9781d55e392 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/types.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/char.traits.specializations.wchar.t/types.pass.cpp
@@ -19,11 +19,13 @@
 #include <string>
 #include <type_traits>
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::char_traits<wchar_t>::char_type, wchar_t>::value), "");
     static_assert((std::is_same<std::char_traits<wchar_t>::int_type, std::wint_t>::value), "");
     static_assert((std::is_same<std::char_traits<wchar_t>::off_type, std::streamoff>::value), "");
     static_assert((std::is_same<std::char_traits<wchar_t>::pos_type, std::wstreampos>::value), "");
     static_assert((std::is_same<std::char_traits<wchar_t>::state_type, std::mbstate_t>::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.specializations/nothing_to_do.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.specializations/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.specializations/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.specializations/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/char.traits.typedefs/nothing_to_do.pass.cpp b/libcxx/test/std/strings/char.traits/char.traits.typedefs/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/strings/char.traits/char.traits.typedefs/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/char.traits.typedefs/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/char.traits/nothing_to_do.pass.cpp b/libcxx/test/std/strings/char.traits/nothing_to_do.pass.cpp
index f77636c8475..1f764da05d6 100644
--- a/libcxx/test/std/strings/char.traits/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/char.traits/nothing_to_do.pass.cpp
@@ -6,6 +6,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.classes/typedefs.pass.cpp b/libcxx/test/std/strings/string.classes/typedefs.pass.cpp
index 14fe3887705..cbc028391b5 100644
--- a/libcxx/test/std/strings/string.classes/typedefs.pass.cpp
+++ b/libcxx/test/std/strings/string.classes/typedefs.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     static_assert((std::is_same<std::string, std::basic_string<char> >::value), "");
     static_assert((std::is_same<std::wstring, std::basic_string<wchar_t> >::value), "");
@@ -33,4 +33,6 @@ int main()
     static_assert((std::is_same<std::u16string, std::basic_string<char16_t> >::value), "");
     static_assert((std::is_same<std::u32string, std::basic_string<char32_t> >::value), "");
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stod.pass.cpp b/libcxx/test/std/strings/string.conversions/stod.pass.cpp
index 9909497e696..d13b695f21c 100644
--- a/libcxx/test/std/strings/string.conversions/stod.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stod.pass.cpp
@@ -18,7 +18,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stod("0") == 0);
     assert(std::stod(L"0") == 0);
@@ -185,4 +185,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stof.pass.cpp b/libcxx/test/std/strings/string.conversions/stof.pass.cpp
index 8e7f4b4ecfc..2c8e4c9b927 100644
--- a/libcxx/test/std/strings/string.conversions/stof.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stof.pass.cpp
@@ -22,7 +22,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stof("0") == 0);
     assert(std::stof(L"0") == 0);
@@ -186,4 +186,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stoi.pass.cpp b/libcxx/test/std/strings/string.conversions/stoi.pass.cpp
index 36998336c2e..b3e41633126 100644
--- a/libcxx/test/std/strings/string.conversions/stoi.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stoi.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stoi("0") == 0);
     assert(std::stoi(L"0") == 0);
@@ -109,4 +109,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stol.pass.cpp b/libcxx/test/std/strings/string.conversions/stol.pass.cpp
index 8e18a0088ca..ef0cbb4ed3c 100644
--- a/libcxx/test/std/strings/string.conversions/stol.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stol.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stol("0") == 0);
     assert(std::stol(L"0") == 0);
@@ -113,4 +113,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stold.pass.cpp b/libcxx/test/std/strings/string.conversions/stold.pass.cpp
index 4677bd7d2eb..5b21fd0e345 100644
--- a/libcxx/test/std/strings/string.conversions/stold.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stold.pass.cpp
@@ -19,7 +19,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stold("0") == 0);
     assert(std::stold(L"0") == 0);
@@ -188,4 +188,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stoll.pass.cpp b/libcxx/test/std/strings/string.conversions/stoll.pass.cpp
index f8a5a6b0e0f..73d5e82015f 100644
--- a/libcxx/test/std/strings/string.conversions/stoll.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stoll.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stoll("0") == 0);
     assert(std::stoll(L"0") == 0);
@@ -112,4 +112,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stoul.pass.cpp b/libcxx/test/std/strings/string.conversions/stoul.pass.cpp
index e60a6a071ad..6ef861396cd 100644
--- a/libcxx/test/std/strings/string.conversions/stoul.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stoul.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stoul("0") == 0);
     assert(std::stoul(L"0") == 0);
@@ -111,4 +111,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/stoull.pass.cpp b/libcxx/test/std/strings/string.conversions/stoull.pass.cpp
index 32369664d08..3e21c683af4 100644
--- a/libcxx/test/std/strings/string.conversions/stoull.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/stoull.pass.cpp
@@ -21,7 +21,7 @@
 
 #include "test_macros.h"
 
-int main()
+int main(int, char**)
 {
     assert(std::stoull("0") == 0);
     assert(std::stoull(L"0") == 0);
@@ -112,4 +112,6 @@ int main()
         assert(idx == 0);
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/to_string.pass.cpp b/libcxx/test/std/strings/string.conversions/to_string.pass.cpp
index 864425134e0..23729cd4f49 100644
--- a/libcxx/test/std/strings/string.conversions/to_string.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/to_string.pass.cpp
@@ -112,7 +112,7 @@ test_float()
     }
 }
 
-int main()
+int main(int, char**)
 {
     test_signed<int>();
     test_signed<long>();
@@ -123,4 +123,6 @@ int main()
     test_float<float>();
     test_float<double>();
     test_float<long double>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.conversions/to_wstring.pass.cpp b/libcxx/test/std/strings/string.conversions/to_wstring.pass.cpp
index 82c3f617b9e..02a262a0f29 100644
--- a/libcxx/test/std/strings/string.conversions/to_wstring.pass.cpp
+++ b/libcxx/test/std/strings/string.conversions/to_wstring.pass.cpp
@@ -112,7 +112,7 @@ test_float()
     }
 }
 
-int main()
+int main(int, char**)
 {
     test_signed<int>();
     test_signed<long>();
@@ -123,4 +123,6 @@ int main()
     test_float<float>();
     test_float<double>();
     test_float<long double>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/char.bad.fail.cpp b/libcxx/test/std/strings/string.view/char.bad.fail.cpp
index 3d04cd085c5..522466613ca 100644
--- a/libcxx/test/std/strings/string.view/char.bad.fail.cpp
+++ b/libcxx/test/std/strings/string.view/char.bad.fail.cpp
@@ -26,7 +26,7 @@ private:
     int two;
 };
 
-int main()
+int main(int, char**)
 {
     {
 //  array
@@ -49,4 +49,6 @@ int main()
     std::basic_string_view<NotStandardLayout, test_traits<NotStandardLayout> > sv;
 //  expected-error-re@string_view:* {{static_assert failed{{.*}} "Character type of basic_string_view must be standard-layout"}}
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.access/at.pass.cpp b/libcxx/test/std/strings/string.view/string.view.access/at.pass.cpp
index b4b2667bbe2..3d741c33ffb 100644
--- a/libcxx/test/std/strings/string.view/string.view.access/at.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.access/at.pass.cpp
@@ -36,7 +36,7 @@ void test ( const CharT *s, size_t len ) {
 #endif
 }
 
-int main () {
+int main(int, char**) {
     test ( "ABCDE", 5 );
     test ( "a", 1 );
 
@@ -59,4 +59,6 @@ int main () {
     static_assert ( sv.at(1) == 'B', "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.access/back.pass.cpp b/libcxx/test/std/strings/string.view/string.view.access/back.pass.cpp
index 8c8fd420d79..4505f1cf981 100644
--- a/libcxx/test/std/strings/string.view/string.view.access/back.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.access/back.pass.cpp
@@ -24,7 +24,7 @@ bool test ( const CharT *s, size_t len ) {
     return &sv.back() == s + len - 1;
     }
 
-int main () {
+int main(int, char**) {
     assert ( test ( "ABCDE", 5 ));
     assert ( test ( "a", 1 ));
 
@@ -46,4 +46,6 @@ int main () {
     static_assert ( sv.back()  == 'B', "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.access/data.pass.cpp b/libcxx/test/std/strings/string.view/string.view.access/data.pass.cpp
index 85e02ceb0a7..9ab83dfb2f5 100644
--- a/libcxx/test/std/strings/string.view/string.view.access/data.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.access/data.pass.cpp
@@ -27,7 +27,7 @@ void test ( const CharT *s, size_t len ) {
 #endif
     }
 
-int main () {
+int main(int, char**) {
     test ( "ABCDE", 5 );
     test ( "a", 1 );
 
@@ -50,4 +50,6 @@ int main () {
     static_assert( sv.data() == s, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.access/front.pass.cpp b/libcxx/test/std/strings/string.view/string.view.access/front.pass.cpp
index 6e73202d676..554ed1bab12 100644
--- a/libcxx/test/std/strings/string.view/string.view.access/front.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.access/front.pass.cpp
@@ -24,7 +24,7 @@ bool test ( const CharT *s, size_t len ) {
     return &sv.front() == s;
     }
 
-int main () {
+int main(int, char**) {
     assert ( test ( "ABCDE", 5 ));
     assert ( test ( "a", 1 ));
 
@@ -46,4 +46,6 @@ int main () {
     static_assert ( sv.front()  == 'A', "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.access/index.pass.cpp b/libcxx/test/std/strings/string.view/string.view.access/index.pass.cpp
index 87598dffe73..33992de7c05 100644
--- a/libcxx/test/std/strings/string.view/string.view.access/index.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.access/index.pass.cpp
@@ -26,7 +26,7 @@ void test ( const CharT *s, size_t len ) {
         }
     }
 
-int main () {
+int main(int, char**) {
     test ( "ABCDE", 5 );
     test ( "a", 1 );
 
@@ -49,4 +49,6 @@ int main () {
     static_assert ( sv[1]  == 'B', "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.capacity/capacity.pass.cpp b/libcxx/test/std/strings/string.view/string.view.capacity/capacity.pass.cpp
index 93cc762832f..025d905a333 100644
--- a/libcxx/test/std/strings/string.view/string.view.capacity/capacity.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.capacity/capacity.pass.cpp
@@ -62,7 +62,7 @@ void test2 ( const CharT *s, size_t len ) {
     }
 }
 
-int main () {
+int main(int, char**) {
     test1<std::string_view> ();
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
     test1<std::u8string_view> ();
@@ -99,4 +99,6 @@ int main () {
     test2 ( U"a", 1 );
     test2 ( U"", 0 );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.capacity/empty.fail.cpp b/libcxx/test/std/strings/string.view/string.view.capacity/empty.fail.cpp
index 74bd413020d..1dd1dcf7cb5 100644
--- a/libcxx/test/std/strings/string.view/string.view.capacity/empty.fail.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.capacity/empty.fail.cpp
@@ -20,8 +20,10 @@
 
 #include "test_macros.h"
 
-int main ()
+int main(int, char**)
 {
     std::string_view c;
     c.empty();  // expected-error {{ignoring return value of function declared with 'nodiscard' attribute}}
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
index bb6c3431652..e771bd328a9 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(S lhs, const typename S::value_type* rhs, bool x)
     assert((rhs == lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -65,4 +65,6 @@ int main()
     static_assert (!("abcde0" == sv2), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
index bb142b0b3c3..d27d4c44588 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const std::string &lhs, S rhs, bool x)
     assert((rhs == lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,5 +46,7 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghij"), false);
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), true);
     }
+
+  return 0;
 }
 
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
index d7b113c120b..259711e3c52 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opeq.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(S lhs, S rhs, bool x)
     assert((rhs == lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -58,4 +58,6 @@ int main()
     static_assert (!(sv1 == sv3), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
index 4f32425dc49..5fa57eb394c 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs >= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (  "abcde0" >= sv2, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
index 9cbe389cd48..dddaa390ed3 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs >= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", true, false);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true, true);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
index 81fee1f3953..d35bea575c8 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opge.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs >= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (  sv2 >= sv1,  "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
index c295645a9b7..80dcc7b497b 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs > lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (  "abcde0" > sv2, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
index b07b6a7aca2..84c9478bfc5 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs > lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", true, false);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false, false);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
index 984f2c6a32e..ec31d5c2c1d 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opgt.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs > lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (  sv2 > sv1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
index 81d0d167a00..4f582239a83 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs <= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (!("abcde0" <= sv2), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
index 3cdb0215e48..80e80757bf9 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs <= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", false, true);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", true, true);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
index 3ec0222f66f..b1c18612425 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/ople.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs <= lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (!(sv2 <= sv1), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
index f8093c86a73..14bba2abfe6 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(const typename S::value_type* lhs, const S& rhs, bool x, bool y)
     assert((rhs < lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -68,4 +68,6 @@ int main()
     static_assert (!("abcde0" < sv2), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
index e7341f17d1f..f611bac7a84 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const S& lhs, const typename S::value_type* rhs, bool x, bool y)
     assert((rhs < lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test(S("abcdefghijklmnopqrst"), "abcdefghij", false, true);
     test(S("abcdefghijklmnopqrst"), "abcdefghijklmnopqrst", false, false);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
index a7e51f9af8c..f44e373619a 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/oplt.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(const S& lhs, const S& rhs, bool x, bool y)
     assert((rhs < lhs) == y);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -61,4 +61,6 @@ int main()
     static_assert (!(sv2 < sv1), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
index 1531626a884..6b8add83146 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.pointer.pass.cpp
@@ -27,7 +27,7 @@ test(S lhs, const typename S::value_type* rhs, bool x)
     assert((rhs != lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -66,4 +66,6 @@ int main()
     static_assert (  "abcde0" != sv2, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
index 8e5539a8079..613eaf7b32f 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string.pass.cpp
@@ -25,7 +25,7 @@ test(const std::string &lhs, S rhs, bool x)
     assert((rhs != lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -46,4 +46,6 @@ int main()
     test("abcdefghijklmnopqrst", S("abcdefghij"), true);
     test("abcdefghijklmnopqrst", S("abcdefghijklmnopqrst"), false);
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
index 0e01e94db43..90d153335ff 100644
--- a/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.comparison/opne.string_view.string_view.pass.cpp
@@ -26,7 +26,7 @@ test(S lhs, S rhs, bool x)
     assert((rhs != lhs) == x);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -58,4 +58,6 @@ int main()
     static_assert (   sv1 != sv3,  "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/assign.pass.cpp b/libcxx/test/std/strings/string.view/string.view.cons/assign.pass.cpp
index 8247c53c739..b2bf8ed7198 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/assign.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/assign.pass.cpp
@@ -29,7 +29,7 @@ bool test (T sv0)
     return sv0.size() == sv1.size() && sv0.data() == sv1.data();
     }
 
-int main () {
+int main(int, char**) {
 
     assert( test<std::string_view>    (  "1234"));
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -54,4 +54,6 @@ int main () {
 #endif
     static_assert( test<std::wstring_view>   ({ L"abc", 3}), "");
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/default.pass.cpp b/libcxx/test/std/strings/string.view/string.view.cons/default.pass.cpp
index fe1fa974012..07a453b2369 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/default.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/default.pass.cpp
@@ -35,7 +35,7 @@ void test () {
     }
 }
 
-int main () {
+int main(int, char**) {
     test<std::string_view> ();
     test<std::u16string_view> ();
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -44,4 +44,6 @@ int main () {
     test<std::u32string_view> ();
     test<std::wstring_view> ();
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/from_literal.pass.cpp b/libcxx/test/std/strings/string.view/string.view.cons/from_literal.pass.cpp
index 7430f4ad6b5..bcd83da74c6 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/from_literal.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/from_literal.pass.cpp
@@ -39,7 +39,7 @@ void test ( const CharT *s ) {
     }
 
 
-int main () {
+int main(int, char**) {
 
     test ( "QBCDE" );
     test ( "A" );
@@ -65,4 +65,6 @@ int main () {
     static_assert ( sv1.size() == 5, "");
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/from_ptr_len.pass.cpp b/libcxx/test/std/strings/string.view/string.view.cons/from_ptr_len.pass.cpp
index 8ad0449aaca..92ae675a399 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/from_ptr_len.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/from_ptr_len.pass.cpp
@@ -31,7 +31,7 @@ void test ( const CharT *s, size_t sz ) {
     }
 }
 
-int main () {
+int main(int, char**) {
 
     test ( "QBCDE", 5 );
     test ( "QBCDE", 2 );
@@ -82,4 +82,6 @@ int main () {
     }
 #endif
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/from_string.pass.cpp b/libcxx/test/std/strings/string.view/string.view.cons/from_string.pass.cpp
index 5e4a2d31908..2043d662a7a 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/from_string.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/from_string.pass.cpp
@@ -31,7 +31,7 @@ void test ( const std::basic_string<CharT, Traits> &str ) {
     assert ( sv1.data() == str.data());
 }
 
-int main () {
+int main(int, char**) {
 
     test ( std::string("QBCDE") );
     test ( std::string("") );
@@ -61,4 +61,6 @@ int main () {
     test ( std::basic_string<char, dummy_char_traits>("") );
     test ( std::basic_string<char, dummy_char_traits>() );
 
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/from_string1.fail.cpp b/libcxx/test/std/strings/string.view/string.view.cons/from_string1.fail.cpp
index 343600625e8..3c464d7fe3e 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/from_string1.fail.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/from_string1.fail.cpp
@@ -18,7 +18,7 @@
 
 struct dummy_char_traits : public std::char_traits<char> {};
 
-int main () {
+int main(int, char**) {
     using string_view = std::basic_string_view<char>;
     using string      = std::              basic_string     <char, dummy_char_traits>;
 
@@ -28,4 +28,6 @@ int main () {
     assert ( sv1.size() == s.size());
     assert ( sv1.data() == s.data());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/from_string2.fail.cpp b/libcxx/test/std/strings/string.view/string.view.cons/from_string2.fail.cpp
index 2a0544defea..482d220013b 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/from_string2.fail.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/from_string2.fail.cpp
@@ -18,7 +18,7 @@
 
 struct dummy_char_traits : public std::char_traits<char> {};
 
-int main () {
+int main(int, char**) {
     using string_view = std::basic_string_view<char, dummy_char_traits>;
     using string      = std::              basic_string     <char>;
 
@@ -28,4 +28,6 @@ int main () {
     assert ( sv1.size() == s.size());
     assert ( sv1.data() == s.data());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.cons/implicit_deduction_guides.pass.cpp b/libcxx/test/std/strings/string.view/string.view.cons/implicit_deduction_guides.pass.cpp
index 3f1f562a475..b95dca63dfd 100644
--- a/libcxx/test/std/strings/string.view/string.view.cons/implicit_deduction_guides.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.cons/implicit_deduction_guides.pass.cpp
@@ -26,7 +26,7 @@
 // (2)  basic_string_view(const basic_string_view&)
 // (3)  basic_string_view(const CharT*, size_type)
 // (4)  basic_string_view(const CharT*)
-int main()
+int main(int, char**)
 {
   { // Testing (1)
     // Nothing TODO. Cannot deduce without any arguments.
@@ -61,4 +61,6 @@ int main()
     ASSERT_SAME_TYPE(decltype(w), std::wstring_view);
     assert(w == L"abcdef");
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_char_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_char_size.pass.cpp
index 8898d11afbf..82173a93a88 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_char_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_char_size.pass.cpp
@@ -35,7 +35,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(0 <= x && x + 1 <= s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -81,4 +81,6 @@ int main()
     static_assert (sv2.find( 'c', 4 ) == SV::npos, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_char_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_char_size.pass.cpp
index aae4048ac52..4566adabfd3 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_char_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_char_size.pass.cpp
@@ -35,7 +35,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -81,4 +81,6 @@ int main()
     static_assert (sv2.find_first_not_of( 'q', 5 ) == SV::npos, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size.pass.cpp
index 0020e60b801..17c3c5293f0 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size.pass.cpp
@@ -141,7 +141,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -162,4 +162,6 @@ int main()
     static_assert (sv2.find_first_not_of( "lecar", 0) == 1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size_size.pass.cpp
index 52f06967693..707a7a96439 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_pointer_size_size.pass.cpp
@@ -366,7 +366,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -389,4 +389,6 @@ int main()
     static_assert (sv2.find_first_not_of( "lecar", 0, 5) == 1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_string_view_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_string_view_size.pass.cpp
index 9378c6a0f45..37445b578c7 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_not_of_string_view_size.pass.cpp
@@ -137,11 +137,13 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
     test0<S>();
     test1<S>();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_char_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_char_size.pass.cpp
index 6be6ddcd99c..d4916bec32f 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_char_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_char_size.pass.cpp
@@ -35,7 +35,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -79,4 +79,6 @@ int main()
     static_assert (sv2.find_first_of( 'e', 5 ) == SV::npos, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size.pass.cpp
index bc3ea554bde..7e43109afdd 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size.pass.cpp
@@ -141,7 +141,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -162,4 +162,6 @@ int main()
     static_assert (sv2.find_first_of( "lecar", 0) == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size_size.pass.cpp
index cd978436eb5..165fb2362ae 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_pointer_size_size.pass.cpp
@@ -366,7 +366,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -389,4 +389,6 @@ int main()
     static_assert (sv2.find_first_of( "lecar", 0, 5) == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_string_view_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_string_view_size.pass.cpp
index 545f4e51508..c705f0266d8 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_first_of_string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_first_of_string_view_size.pass.cpp
@@ -137,11 +137,13 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
     test0<S>();
     test1<S>();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_char_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_char_size.pass.cpp
index 8d80557d4c5..0b6e6cfb0fa 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_char_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_char_size.pass.cpp
@@ -35,7 +35,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -79,4 +79,6 @@ int main()
     static_assert (sv2.find_last_not_of( 'e', 5 ) == 3, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size.pass.cpp
index f7daf3fa3bd..fe17b779dd9 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size.pass.cpp
@@ -141,7 +141,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -162,4 +162,6 @@ int main()
     static_assert (sv2.find_last_not_of( "lecar", 5) == 3, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size_size.pass.cpp
index 8fd25539525..11a5c27e8da 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_pointer_size_size.pass.cpp
@@ -366,7 +366,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -389,4 +389,6 @@ int main()
     static_assert (sv2.find_last_not_of( "lecar", 5, 0) == 4, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_string_view_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_string_view_size.pass.cpp
index 06a31a1d661..e90e38c0d70 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_not_of_string_view_size.pass.cpp
@@ -137,11 +137,13 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
     test0<S>();
     test1<S>();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_char_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_char_size.pass.cpp
index 147e191b237..fdcf3173671 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_char_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_char_size.pass.cpp
@@ -35,7 +35,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x < s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -79,4 +79,6 @@ int main()
     static_assert (sv2.find_last_of( 'e', 5 ) == 4, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size.pass.cpp
index 5a12718314c..640f4837596 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size.pass.cpp
@@ -141,7 +141,7 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), "htaobedqikfplcgjsmrn", 19);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -162,4 +162,6 @@ int main()
     static_assert (sv2.find_last_of( "lecar", 5) == 4, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size_size.pass.cpp
index 98402982691..e82c935b5ff 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_pointer_size_size.pass.cpp
@@ -366,7 +366,7 @@ void test3()
     test(S("hnbrcplsjfgiktoedmaq"), "qprlsfojamgndekthibc", 21, 20, 19);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -389,4 +389,6 @@ int main()
     static_assert (sv2.find_last_of( "lecar", 5, 5) == 4, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_string_view_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_string_view_size.pass.cpp
index 84b5a96df5d..02c1184eec8 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_last_of_string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_last_of_string_view_size.pass.cpp
@@ -137,11 +137,13 @@ void test1()
     test(S("pniotcfrhqsmgdkjbael"), S("htaobedqikfplcgjsmrn"), 19);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
     test0<S>();
     test1<S>();
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size.pass.cpp
index 2be32a46a95..3f4fee54ef4 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size.pass.cpp
@@ -147,7 +147,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -168,4 +168,6 @@ int main()
     static_assert (sv2.find( "abcde", 1) == SV::npos, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size_size.pass.cpp
index 0f7d295a4a5..74caa6fea7b 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_pointer_size_size.pass.cpp
@@ -366,7 +366,7 @@ void test3()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 21, 20, S::npos);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -390,4 +390,6 @@ int main()
     static_assert (sv2.find( "abcde", 0, 1 ) == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/find_string_view_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/find_string_view_size.pass.cpp
index 0a5cec54eda..ed3b7c11c02 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/find_string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/find_string_view_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), S("abcdeabcdeabcdeabcde"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -161,4 +161,6 @@ int main()
     static_assert (sv2.find(sv2, 1 ) == SV::npos, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/rfind_char_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/rfind_char_size.pass.cpp
index 62f50ed8786..959bb05f871 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/rfind_char_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/rfind_char_size.pass.cpp
@@ -34,7 +34,7 @@ test(const S& s, typename S::value_type c, typename S::size_type x)
         assert(x + 1 <= s.size());
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -80,4 +80,6 @@ int main()
     static_assert (sv2.rfind( 'b', 4 ) == 1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size.pass.cpp
index 0ff2be51fc1..6010083ab14 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size.pass.cpp
@@ -147,7 +147,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -168,4 +168,6 @@ int main()
     static_assert (sv2.rfind( "abcde", 1) == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size_size.pass.cpp
index 18fd8437d7e..c3ca97e7ff9 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/rfind_pointer_size_size.pass.cpp
@@ -365,7 +365,7 @@ void test3()
     test(S("abcdeabcdeabcdeabcde"), "abcdeabcdeabcdeabcde", 21, 20, 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -389,4 +389,6 @@ int main()
     static_assert (sv2.rfind( "abcde", 0, 1 ) == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.find/rfind_string_view_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.find/rfind_string_view_size.pass.cpp
index dfc4a836149..c4ceef33136 100644
--- a/libcxx/test/std/strings/string.view/string.view.find/rfind_string_view_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.find/rfind_string_view_size.pass.cpp
@@ -140,7 +140,7 @@ void test1()
     test(S("abcdeabcdeabcdeabcde"), S("abcdeabcdeabcdeabcde"), 0);
 }
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view S;
@@ -161,4 +161,6 @@ int main()
     static_assert (sv2.rfind(sv2, 1) == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.hash/enabled_hashes.pass.cpp b/libcxx/test/std/strings/string.view/string.view.hash/enabled_hashes.pass.cpp
index 21dcbdf3039..d52f16303b6 100644
--- a/libcxx/test/std/strings/string.view/string.view.hash/enabled_hashes.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.hash/enabled_hashes.pass.cpp
@@ -17,7 +17,7 @@
 
 #include "poisoned_hash_helper.hpp"
 
-int main() {
+int main(int, char**) {
   test_library_hash_specializations_available();
   {
     test_hash_enabled_for_type<std::string_view>();
@@ -30,4 +30,6 @@ int main() {
     test_hash_enabled_for_type<std::u32string_view>();
 #endif
   }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp
index 7cb7754038c..0e296f2096d 100644
--- a/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.hash/string_view.pass.cpp
@@ -55,7 +55,7 @@ test()
     assert(sh(ss2) == h(s2));
 }
 
-int main()
+int main(int, char**)
 {
     test<std::string_view>();
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -66,4 +66,6 @@ int main()
     test<std::u32string_view>();
 #endif  // _LIBCPP_HAS_NO_UNICODE_CHARS
     test<std::wstring_view>();
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.io/stream_insert.pass.cpp b/libcxx/test/std/strings/string.view/string.view.io/stream_insert.pass.cpp
index c721b2fcfe3..d4dcbdc6b0a 100644
--- a/libcxx/test/std/strings/string.view/string.view.io/stream_insert.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.io/stream_insert.pass.cpp
@@ -20,7 +20,7 @@
 using std::string_view;
 using std::wstring_view;
 
-int main()
+int main(int, char**)
 {
     {
         std::ostringstream out;
@@ -54,4 +54,6 @@ int main()
         assert(out.good());
         assert(L"   " + s == out.str());
     }
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.iterators/begin.pass.cpp b/libcxx/test/std/strings/string.view/string.view.iterators/begin.pass.cpp
index 0926f7f9022..ba700c8abbc 100644
--- a/libcxx/test/std/strings/string.view/string.view.iterators/begin.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.iterators/begin.pass.cpp
@@ -39,7 +39,7 @@ test(S s)
 }
 
 
-int main()
+int main(int, char**)
 {
     typedef std::string_view    string_view;
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -90,4 +90,6 @@ int main()
     static_assert (   *wsv.cbegin() ==   wsv[0], "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.iterators/end.pass.cpp b/libcxx/test/std/strings/string.view/string.view.iterators/end.pass.cpp
index 1287cc201ba..59c29e2dbdd 100644
--- a/libcxx/test/std/strings/string.view/string.view.iterators/end.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.iterators/end.pass.cpp
@@ -48,7 +48,7 @@ test(S s)
 }
 
 
-int main()
+int main(int, char**)
 {
     typedef std::string_view    string_view;
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -99,4 +99,6 @@ int main()
     static_assert (   wsv.begin() !=   wsv.cend(), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.iterators/rbegin.pass.cpp b/libcxx/test/std/strings/string.view/string.view.iterators/rbegin.pass.cpp
index 43d1906c8f5..a57d7b454a3 100644
--- a/libcxx/test/std/strings/string.view/string.view.iterators/rbegin.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.iterators/rbegin.pass.cpp
@@ -40,7 +40,7 @@ test(S s)
 }
 
 
-int main()
+int main(int, char**)
 {
     typedef std::string_view    string_view;
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -91,4 +91,6 @@ int main()
     static_assert (   *wsv.crbegin() ==   wsv[2], "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.iterators/rend.pass.cpp b/libcxx/test/std/strings/string.view/string.view.iterators/rend.pass.cpp
index a4eed7d9743..e0db02c22f6 100644
--- a/libcxx/test/std/strings/string.view/string.view.iterators/rend.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.iterators/rend.pass.cpp
@@ -48,7 +48,7 @@ test(S s)
 }
 
 
-int main()
+int main(int, char**)
 {
     typedef std::string_view    string_view;
 #if defined(__cpp_lib_char8_t) && __cpp_lib_char8_t >= 201811L
@@ -99,4 +99,6 @@ int main()
     static_assert (   *--wsv.crend() ==   wsv[0], "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.modifiers/remove_prefix.pass.cpp b/libcxx/test/std/strings/string.view/string.view.modifiers/remove_prefix.pass.cpp
index 08fe79e8f82..2287ba6c800 100644
--- a/libcxx/test/std/strings/string.view/string.view.modifiers/remove_prefix.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.modifiers/remove_prefix.pass.cpp
@@ -47,7 +47,7 @@ constexpr size_t test_ce ( size_t n, size_t k ) {
 }
 #endif
 
-int main () {
+int main(int, char**) {
     test ( "ABCDE", 5 );
     test ( "a", 1 );
     test ( "", 0 );
@@ -74,4 +74,6 @@ int main () {
     static_assert ( test_ce ( 9, 3 ) == 6, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.modifiers/remove_suffix.pass.cpp b/libcxx/test/std/strings/string.view/string.view.modifiers/remove_suffix.pass.cpp
index be9ca1e1fc9..0636bcea957 100644
--- a/libcxx/test/std/strings/string.view/string.view.modifiers/remove_suffix.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.modifiers/remove_suffix.pass.cpp
@@ -47,7 +47,7 @@ constexpr size_t test_ce ( size_t n, size_t k ) {
 }
 #endif
 
-int main () {
+int main(int, char**) {
     test ( "ABCDE", 5 );
     test ( "a", 1 );
     test ( "", 0 );
@@ -74,4 +74,6 @@ int main () {
     static_assert ( test_ce ( 9, 3 ) == 6, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.modifiers/swap.pass.cpp b/libcxx/test/std/strings/string.view/string.view.modifiers/swap.pass.cpp
index 9b8eedd701b..2fc286e96a5 100644
--- a/libcxx/test/std/strings/string.view/string.view.modifiers/swap.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.modifiers/swap.pass.cpp
@@ -46,7 +46,7 @@ constexpr size_t test_ce ( size_t n, size_t k ) {
 #endif
 
 
-int main () {
+int main(int, char**) {
     test ( "ABCDE", 5 );
     test ( "a", 1 );
     test ( "", 0 );
@@ -72,4 +72,6 @@ int main () {
     static_assert ( test_ce (0, 1) == 1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.nonmem/quoted.pass.cpp b/libcxx/test/std/strings/string.view/string.view.nonmem/quoted.pass.cpp
index f335da9585d..ecc24abf4be 100644
--- a/libcxx/test/std/strings/string.view/string.view.nonmem/quoted.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.nonmem/quoted.pass.cpp
@@ -160,7 +160,7 @@ std::wstring unquote ( const wchar_t *p, wchar_t delim='"', wchar_t escape='\\'
     return s;
 }
 
-int main()
+int main(int, char**)
 {
     round_trip    (  "" );
     round_trip_ws (  "" );
@@ -207,7 +207,11 @@ int main()
 
     assert ( unquote (  "" ) ==  "" ); // nothing there
     assert ( unquote ( L"" ) == L"" ); // nothing there
-    }
+
+    return 0;
+}
 #else
-int main() {}
+int main(int, char**) {
+  return 0;
+}
 #endif
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer.pass.cpp
index e9a854b34fa..0c04ce5e48b 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer.pass.cpp
@@ -32,7 +32,7 @@ test( const CharT *s1, const CharT *s2, int expected)
     test1 ( sv1, s2, expected );
 }
 
-int main()
+int main(int, char**)
 {
     {
     test("", "", 0);
@@ -123,4 +123,6 @@ int main()
     static_assert ( sv2.compare("abcde") == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer_size.pass.cpp
index 6f45222ff6c..974e687100d 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/compare.pointer_size.pass.cpp
@@ -354,7 +354,7 @@ void test2()
 }
 
 
-int main()
+int main(int, char**)
 {
     test0();
     test1();
@@ -449,4 +449,6 @@ int main()
     static_assert ( sv2.compare(0, 6, "abcde") == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv.pass.cpp
index 452addc12df..73773fb26ee 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv.pass.cpp
@@ -354,7 +354,7 @@ void test2()
 }
 
 
-int main () {
+int main(int, char**) {
     test0();
     test1();
     test2();
@@ -398,4 +398,6 @@ int main () {
     static_assert ( sv1.compare(2, 4, sv2) == 1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_pointer_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_pointer_size.pass.cpp
index d11f003313f..df4e7394db9 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_pointer_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_pointer_size.pass.cpp
@@ -1291,7 +1291,7 @@ void test11()
     }
 
 
-int main () {
+int main(int, char**) {
     test0();
     test1();
     test2();
@@ -1349,4 +1349,6 @@ int main () {
     static_assert ( sv2.compare(0, 0, "abcde", 1, 0) == 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_size_size.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_size_size.pass.cpp
index 3f6e5787603..56b6ec1f404 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_size_size.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/compare.size_size_sv_size_size.pass.cpp
@@ -5747,7 +5747,7 @@ void test54()
 }
 
 
-int main () {
+int main(int, char**) {
     test0();
     test1();
     test2();
@@ -5844,4 +5844,6 @@ int main () {
     static_assert ( sv1.compare(2, 4, "abcde", 3, 4) == -1, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/compare.sv.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/compare.sv.pass.cpp
index e65a7451f47..9c27f267459 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/compare.sv.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/compare.sv.pass.cpp
@@ -34,7 +34,7 @@ void test ( const CharT *s1, const CharT  *s2, int expected ) {
     test1(sv1, sv2, expected);
 }
 
-int main () {
+int main(int, char**) {
 
     test("",                     "", 0);
     test("",                     "abcde", -5);
@@ -118,4 +118,6 @@ int main () {
     static_assert ( sv2.compare(sv3)  < 0, "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
index 3ec48b08c33..e96650992cb 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/copy.pass.cpp
@@ -77,7 +77,7 @@ void test ( const CharT *s ) {
 
 }
 
-int main () {
+int main(int, char**) {
     test ( "ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
     test ( "ABCDE");
     test ( "a" );
@@ -99,4 +99,6 @@ int main () {
     test ( U"a" );
     test ( U"" );
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
index 4391bb51342..c2fd01f5724 100644
--- a/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.ops/substr.pass.cpp
@@ -69,7 +69,7 @@ void test ( const CharT *s ) {
     test1(sv1, sv1.size() + 1, string_view_t::npos);
 }
 
-int main () {
+int main(int, char**) {
     test ( "ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
     test ( "ABCDE");
     test ( "a" );
@@ -117,4 +117,6 @@ int main () {
     }
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.synop/nothing_to_do.pass.cpp b/libcxx/test/std/strings/string.view/string.view.synop/nothing_to_do.pass.cpp
index 3f07051d03a..45edec7f4b0 100644
--- a/libcxx/test/std/strings/string.view/string.view.synop/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.synop/nothing_to_do.pass.cpp
@@ -8,4 +8,6 @@
 
 #include <string_view>
 
-int main () {}
+int main(int, char**) {
+  return 0;
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.template/ends_with.char.pass.cpp b/libcxx/test/std/strings/string.view/string.view.template/ends_with.char.pass.cpp
index c89fdb8e4e8..c0373307427 100644
--- a/libcxx/test/std/strings/string.view/string.view.template/ends_with.char.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.template/ends_with.char.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "constexpr_char_traits.hpp"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view SV;
@@ -43,4 +43,6 @@ int main()
     static_assert (!sv2.ends_with('x'), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.template/ends_with.ptr.pass.cpp b/libcxx/test/std/strings/string.view/string.view.template/ends_with.ptr.pass.cpp
index 4ef1c8e2f98..64caf5cc0d5 100644
--- a/libcxx/test/std/strings/string.view/string.view.template/ends_with.ptr.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.template/ends_with.ptr.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "constexpr_char_traits.hpp"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view SV;
@@ -100,4 +100,6 @@ int main()
     static_assert ( svNot.ends_with("def"), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.template/ends_with.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.template/ends_with.string_view.pass.cpp
index 2d115c104b4..b5f67f8ddd1 100644
--- a/libcxx/test/std/strings/string.view/string.view.template/ends_with.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.template/ends_with.string_view.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "constexpr_char_traits.hpp"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view SV;
@@ -100,4 +100,6 @@ int main()
     static_assert ( svNot.ends_with(svNot), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.template/nothing_to_do.pass.cpp b/libcxx/test/std/strings/string.view/string.view.template/nothing_to_do.pass.cpp
index 3f07051d03a..45edec7f4b0 100644
--- a/libcxx/test/std/strings/string.view/string.view.template/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.template/nothing_to_do.pass.cpp
@@ -8,4 +8,6 @@
 
 #include <string_view>
 
-int main () {}
+int main(int, char**) {
+  return 0;
+}
diff --git a/libcxx/test/std/strings/string.view/string.view.template/starts_with.char.pass.cpp b/libcxx/test/std/strings/string.view/string.view.template/starts_with.char.pass.cpp
index d35222bbf87..d43944fdec7 100644
--- a/libcxx/test/std/strings/string.view/string.view.template/starts_with.char.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.template/starts_with.char.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "constexpr_char_traits.hpp"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view SV;
@@ -43,4 +43,6 @@ int main()
     static_assert (!sv2.starts_with('x'), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.template/starts_with.ptr.pass.cpp b/libcxx/test/std/strings/string.view/string.view.template/starts_with.ptr.pass.cpp
index a3ffde5c584..ce651ec57e0 100644
--- a/libcxx/test/std/strings/string.view/string.view.template/starts_with.ptr.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.template/starts_with.ptr.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "constexpr_char_traits.hpp"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view SV;
@@ -100,4 +100,6 @@ int main()
     static_assert ( svNot.starts_with("def"), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string.view.template/starts_with.string_view.pass.cpp b/libcxx/test/std/strings/string.view/string.view.template/starts_with.string_view.pass.cpp
index 5a5adbd8470..3d184bae0eb 100644
--- a/libcxx/test/std/strings/string.view/string.view.template/starts_with.string_view.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string.view.template/starts_with.string_view.pass.cpp
@@ -17,7 +17,7 @@
 #include "test_macros.h"
 #include "constexpr_char_traits.hpp"
 
-int main()
+int main(int, char**)
 {
     {
     typedef std::string_view SV;
@@ -100,4 +100,6 @@ int main()
     static_assert ( svNot.starts_with(svNot), "" );
     }
 #endif
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string_view.literals/literal.pass.cpp b/libcxx/test/std/strings/string.view/string_view.literals/literal.pass.cpp
index c7d0e054df1..a8a1dff6404 100644
--- a/libcxx/test/std/strings/string.view/string_view.literals/literal.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string_view.literals/literal.pass.cpp
@@ -23,7 +23,7 @@
     typedef std::string_view   u8string_view;
 #endif
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals::string_view_literals;
 
@@ -69,4 +69,6 @@ int main()
     static_assert(noexcept( L"ABC"sv), "");
     static_assert(noexcept( u"ABC"sv), "");
     static_assert(noexcept( U"ABC"sv), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string_view.literals/literal1.fail.cpp b/libcxx/test/std/strings/string.view/string_view.literals/literal1.fail.cpp
index 05e66bf1eaf..5bf108bbef2 100644
--- a/libcxx/test/std/strings/string.view/string_view.literals/literal1.fail.cpp
+++ b/libcxx/test/std/strings/string.view/string_view.literals/literal1.fail.cpp
@@ -14,9 +14,11 @@
 #include <string_view>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using std::string_view;
 
     string_view foo  =   ""sv;  // should fail w/conversion operator not found
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string_view.literals/literal1.pass.cpp b/libcxx/test/std/strings/string.view/string_view.literals/literal1.pass.cpp
index 956d7d26a32..ba667e09cd1 100644
--- a/libcxx/test/std/strings/string.view/string_view.literals/literal1.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string_view.literals/literal1.pass.cpp
@@ -15,10 +15,12 @@
 #include <string_view>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals;
 
     std::string_view foo  =   ""sv;
     assert(foo.length() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string_view.literals/literal2.fail.cpp b/libcxx/test/std/strings/string.view/string_view.literals/literal2.fail.cpp
index 672201bb9a0..2287e1ce92a 100644
--- a/libcxx/test/std/strings/string.view/string_view.literals/literal2.fail.cpp
+++ b/libcxx/test/std/strings/string.view/string_view.literals/literal2.fail.cpp
@@ -14,7 +14,9 @@
 #include <string_view>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     std::string_view foo  =   ""sv;  // should fail w/conversion operator not found
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string_view.literals/literal2.pass.cpp b/libcxx/test/std/strings/string.view/string_view.literals/literal2.pass.cpp
index 653738dc5a3..cb49280bfec 100644
--- a/libcxx/test/std/strings/string.view/string_view.literals/literal2.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string_view.literals/literal2.pass.cpp
@@ -15,10 +15,12 @@
 #include <string_view>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std::literals::string_view_literals;
 
     std::string_view foo  =   ""sv;
     assert(foo.length() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/string_view.literals/literal3.pass.cpp b/libcxx/test/std/strings/string.view/string_view.literals/literal3.pass.cpp
index 814ec0cbdfe..710933dd95a 100644
--- a/libcxx/test/std/strings/string.view/string_view.literals/literal3.pass.cpp
+++ b/libcxx/test/std/strings/string.view/string_view.literals/literal3.pass.cpp
@@ -15,10 +15,12 @@
 #include <string_view>
 #include <cassert>
 
-int main()
+int main(int, char**)
 {
     using namespace std;
 
     string_view foo  =   ""sv;
     assert(foo.length() == 0);
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/traits_mismatch.fail.cpp b/libcxx/test/std/strings/string.view/traits_mismatch.fail.cpp
index 6a32051a1c3..5cf3fa94793 100644
--- a/libcxx/test/std/strings/string.view/traits_mismatch.fail.cpp
+++ b/libcxx/test/std/strings/string.view/traits_mismatch.fail.cpp
@@ -11,7 +11,9 @@
 
 #include <string_view>
 
-int main()
+int main(int, char**)
 {
     std::basic_string_view<char, std::char_traits<wchar_t>> s;
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/string.view/types.pass.cpp b/libcxx/test/std/strings/string.view/types.pass.cpp
index d8bb0f73737..d90f777babf 100644
--- a/libcxx/test/std/strings/string.view/types.pass.cpp
+++ b/libcxx/test/std/strings/string.view/types.pass.cpp
@@ -67,7 +67,7 @@ test()
     static_assert((std::is_same<typename S::reverse_iterator, typename S::const_reverse_iterator>::value), "");
 }
 
-int main()
+int main(int, char**)
 {
     test<std::char_traits<char> >();
     test<std::char_traits<wchar_t> >();
@@ -76,4 +76,6 @@ int main()
 #endif
     static_assert((std::is_same<std::basic_string_view<char>::traits_type,
                                 std::char_traits<char> >::value), "");
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/strings.erasure/erase.pass.cpp b/libcxx/test/std/strings/strings.erasure/erase.pass.cpp
index 250fe94a6f2..5013300d28b 100644
--- a/libcxx/test/std/strings/strings.erasure/erase.pass.cpp
+++ b/libcxx/test/std/strings/strings.erasure/erase.pass.cpp
@@ -67,9 +67,11 @@ void test()
     test0(S("aba"), opt('c'), S("aba"));
 }
 
-int main()
+int main(int, char**)
 {
     test<std::string>();
     test<std::basic_string<char, std::char_traits<char>, min_allocator<char>>> ();
     test<std::basic_string<char, std::char_traits<char>, test_allocator<char>>> ();
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/strings.erasure/erase_if.pass.cpp b/libcxx/test/std/strings/strings.erasure/erase_if.pass.cpp
index 06b9cc2279a..5f2fb0117f8 100644
--- a/libcxx/test/std/strings/strings.erasure/erase_if.pass.cpp
+++ b/libcxx/test/std/strings/strings.erasure/erase_if.pass.cpp
@@ -67,9 +67,11 @@ void test()
     test0(S("aba"), True,   S(""));
 }
 
-int main()
+int main(int, char**)
 {
     test<std::string>();
     test<std::basic_string<char, std::char_traits<char>, min_allocator<char>>> ();
     test<std::basic_string<char, std::char_traits<char>, test_allocator<char>>> ();
+
+  return 0;
 }
diff --git a/libcxx/test/std/strings/strings.general/nothing_to_do.pass.cpp b/libcxx/test/std/strings/strings.general/nothing_to_do.pass.cpp
index 02fe32ece48..779762e7e99 100644
--- a/libcxx/test/std/strings/strings.general/nothing_to_do.pass.cpp
+++ b/libcxx/test/std/strings/strings.general/nothing_to_do.pass.cpp
@@ -7,6 +7,8 @@
 //
 //===----------------------------------------------------------------------===//
 
-int main()
+int main(int, char**)
 {
+
+  return 0;
 }