Index: docs/Modules.rst
===================================================================
--- docs/Modules.rst
+++ docs/Modules.rst
@@ -174,6 +174,9 @@
 ``-fmodules``
   Enable the modules feature.
 
+``-fbuiltin-module-map``
+  Load the Clang builtins module map file. (Equivalent to ``-fmodule-map-file=<resource dir>/include/module.modulemap``)
+
 ``-fimplicit-module-maps``
   Enable implicit search for module map files named ``module.modulemap`` and similar. This option is implied by ``-fmodules``. If this is disabled with ``-fno-implicit-module-maps``, module map files will only be loaded if they are explicitly specified via ``-fmodule-map-file`` or transitively used by another module map file.
 
Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -553,6 +553,8 @@
 def fborland_extensions : Flag<["-"], "fborland-extensions">, Group<f_Group>, Flags<[CC1Option]>,
   HelpText<"Accept non-standard constructs supported by the Borland compiler">;
 def fbuiltin : Flag<["-"], "fbuiltin">, Group<f_Group>;
+def fbuiltin_module_map : Flag <["-"], "fbuiltin-module-map">, Group<f_Group>,
+  Flags<[DriverOption]>, HelpText<"Load the clang builtins module map file.">;
 def fcaret_diagnostics : Flag<["-"], "fcaret-diagnostics">, Group<f_Group>;
 def fclasspath_EQ : Joined<["-"], "fclasspath=">, Group<f_Group>;
 def fcolor_diagnostics : Flag<["-"], "fcolor-diagnostics">, Group<f_Group>,
Index: lib/Driver/Tools.cpp
===================================================================
--- lib/Driver/Tools.cpp
+++ lib/Driver/Tools.cpp
@@ -5533,6 +5533,18 @@
   // definitions.
   Args.AddAllArgs(CmdArgs, options::OPT_fmodule_map_file);
 
+  // -fbuiltin-module-map can be used to load the clang
+  // builtin headers modulemap file.
+  if (Args.hasArg(options::OPT_fbuiltin_module_map)) {
+    SmallString<128> BuiltinModuleMap(getToolChain().getDriver().ResourceDir);
+    llvm::sys::path::append(BuiltinModuleMap, "include");
+    llvm::sys::path::append(BuiltinModuleMap, "module.modulemap");
+    if (llvm::sys::fs::exists(BuiltinModuleMap)) {
+      CmdArgs.push_back(Args.MakeArgString("-fmodule-map-file=" +
+                                           BuiltinModuleMap));
+    }
+  }
+
   // -fmodule-file can be used to specify files containing precompiled modules.
   if (HaveAnyModules)
     Args.AddAllArgs(CmdArgs, options::OPT_fmodule_file);
Index: test/Driver/modules.m
===================================================================
--- test/Driver/modules.m
+++ test/Driver/modules.m
@@ -51,6 +51,10 @@
 // CHECK-MODULE-MAP-FILES: "-fmodule-map-file=foo.map"
 // CHECK-MODULE-MAP-FILES: "-fmodule-map-file=bar.map"
 
+// RUN: %clang -fmodules -fbuiltin-module-map -### %s 2>&1 | FileCheck -check-prefix=CHECK-BUILTIN-MODULE-MAP %s
+// CHECK-BUILTIN-MODULE-MAP: "-fmodules"
+// CHECK-BUILTIN-MODULE-MAP: "-fmodule-map-file={{.*}}include{{/|\\\\}}module.modulemap"
+
 // RUN: %clang -fmodules -fmodule-file=foo.pcm -fmodule-file=bar.pcm -### %s 2>&1 | FileCheck -check-prefix=CHECK-MODULE-FILES %s
 // CHECK-MODULE-FILES: "-fmodules"
 // CHECK-MODULE-FILES: "-fmodule-file=foo.pcm"
Index: test/Modules/compiler_builtins.m
===================================================================
--- test/Modules/compiler_builtins.m
+++ test/Modules/compiler_builtins.m
@@ -1,6 +1,7 @@
 // RUN: rm -rf %t
 // RUN: %clang_cc1 -fsyntax-only -fmodules -fimplicit-module-maps -fmodules-cache-path=%t %s -I%S/Inputs/System/usr/include -verify
 // RUN: %clang_cc1 -fsyntax-only -std=c99 -fmodules -fimplicit-module-maps -fmodules-cache-path=%t %s -I%S/Inputs/System/usr/include -verify
+// RUN: %clang_cc1 -fsyntax-only -fmodules -fmodule-map-file=%resource_dir/module.modulemap -fmodules-cache-path=%t %s -I%S/Inputs/System/usr/include -verify
 // expected-no-diagnostics
 
 #ifdef __SSE__
Index: test/Modules/compiler_builtins_x86.c
===================================================================
--- test/Modules/compiler_builtins_x86.c
+++ test/Modules/compiler_builtins_x86.c
@@ -1,5 +1,6 @@
 // RUN: rm -rf %t
 // RUN: %clang_cc1 -triple i686-unknown-unknown -fsyntax-only -fmodules -fimplicit-module-maps -fmodules-cache-path=%t %s -verify -ffreestanding
+// RUN: %clang_cc1 -triple i686-unknown-unknown -fsyntax-only -fmodules -fmodule-map-file=%resource_dir/module.modulemap -fmodules-cache-path=%t %s -verify -ffreestanding
 // expected-no-diagnostics
 
 #include<x86intrin.h>
Index: test/lit.cfg
===================================================================
--- test/lit.cfg
+++ test/lit.cfg
@@ -268,6 +268,7 @@
 config.substitutions.append( ('%test_debuginfo', ' ' + config.llvm_src_root + '/utils/test_debuginfo.pl ') )
 config.substitutions.append( ('%itanium_abi_triple', makeItaniumABITriple(config.target_triple)) )
 config.substitutions.append( ('%ms_abi_triple', makeMSABITriple(config.target_triple)) )
+config.substitutions.append( ('%resource_dir', getClangBuiltinIncludeDir(config.clang)) )
 
 # The host triple might not be set, at least if we're compiling clang from
 # an already installed llvm.