6 files changed, 55 insertions, 16 deletions
diff --git a/clang/test/Modules/Inputs/System/usr/include/module.map b/clang/test/Modules/Inputs/System/usr/include/module.map
new file mode 100644
index 00000000000..884b59c80cd
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/module.map
@@ -0,0 +1,21 @@
+module cstd [system] {
+  // Only in compiler support directory
+  module float_constants {
+    header "float.h"
+  }
+
+  // Only in system headers directory
+  module stdio {
+    header "stdio.h"
+  }
+
+  // In both directories (compiler support version wins, does not forward)
+  module stdbool {
+    header "stdbool.h"
+  }
+
+  // In both directories (compiler support version wins, forwards)
+  module stdint {
+    header "stdint.h"
+  }
+}
diff --git a/clang/test/Modules/Inputs/System/usr/include/stdbool.h b/clang/test/Modules/Inputs/System/usr/include/stdbool.h
new file mode 100644
index 00000000000..760d7dc48ef
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/stdbool.h
@@ -0,0 +1 @@
+// Testing hack: does not define bool/true/false.
diff --git a/clang/test/Modules/Inputs/System/usr/include/stdint.h b/clang/test/Modules/Inputs/System/usr/include/stdint.h
new file mode 100644
index 00000000000..e8e50f90290
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/stdint.h
@@ -0,0 +1 @@
+typedef int my_awesome_nonstandard_integer_type;
diff --git a/clang/test/Modules/Inputs/System/usr/include/stdio.h b/clang/test/Modules/Inputs/System/usr/include/stdio.h
new file mode 100644
index 00000000000..9a7b1063032
--- /dev/null
+++ b/clang/test/Modules/Inputs/System/usr/include/stdio.h
@@ -0,0 +1,3 @@
+typedef struct { int id; } FILE;
+int fprintf(FILE*restrict, const char* restrict format, ...);
+
diff --git a/clang/test/Modules/compiler_builtins.m b/clang/test/Modules/compiler_builtins.m
index 5ec2e978b3e..a4f1dc21328 100644
--- a/clang/test/Modules/compiler_builtins.m
+++ b/clang/test/Modules/compiler_builtins.m
@@ -1,22 +1,6 @@
 // RUN: rm -rf %t
 // RUN: %clang -fsyntax-only -fmodules -fmodule-cache-path %t -D__need_wint_t %s -Xclang -verify
 
-@import _Builtin_stdlib.float_constants;
-
-float getFltMax() { return FLT_MAX; }
-
-@import _Builtin_stdlib.limits;
-
-char getCharMax() { return CHAR_MAX; }
-
-// MS limits.h provides size_t.
-// XFAIL: win32
-size_t size; // expected-error{{unknown type name 'size_t'}}
-
-@import _Builtin_stdlib.stdint;
-
-intmax_t value;
-
 #ifdef __SSE__
 @import _Builtin_intrinsics.intel.sse;
 #endif
diff --git a/clang/test/Modules/cstd.m b/clang/test/Modules/cstd.m
new file mode 100644
index 00000000000..8bd5c92cff1
--- /dev/null
+++ b/clang/test/Modules/cstd.m
@@ -0,0 +1,29 @@
+// RUN: rm -rf %t
+// RUN: %clang -fsyntax-only -isysroot %S/Inputs/System -fmodules -fmodule-cache-path %t -D__need_wint_t %s -Xclang -verify
+
+// Supplied by compiler, but referenced from the "/usr/include" module map.
+@import cstd.float_constants;
+
+float getFltMax() { return FLT_MAX; }
+
+// Supplied by the "/usr/include" module map.
+@import cstd.stdio;
+
+void test_fprintf(FILE *file) {
+  fprintf(file, "Hello, modules\n");
+}
+
+// Supplied by compiler, which forwards to the the "/usr/include" version.
+@import cstd.stdint;
+
+my_awesome_nonstandard_integer_type value;
+
+// Supplied by the compiler; that version wins.
+@import cstd.stdbool;
+
+#ifndef bool
+#  error "bool was not defined!"
+#endif
+
+
+