diff --git a/lib/Frontend/CompilerInvocation.cpp b/lib/Frontend/CompilerInvocation.cpp
index 76ceb9b..f1d98b9 100644
--- a/lib/Frontend/CompilerInvocation.cpp
+++ b/lib/Frontend/CompilerInvocation.cpp
@@ -627,6 +627,8 @@
     Res.push_back("-fgnu-keywords");
   if (Opts.MicrosoftExt)
     Res.push_back("-fms-extensions");
+  if (Opts.MicrosoftMode)
+    Res.push_back("-fms-compatibility");
   if (Opts.MSCVersion != 0)
     Res.push_back("-fmsc-version=" + llvm::utostr(Opts.MSCVersion));
   if (Opts.Borland)
@@ -1697,7 +1699,8 @@
                                    OPT_fno_dollars_in_identifiers,
                                    Opts.DollarIdents);
   Opts.PascalStrings = Args.hasArg(OPT_fpascal_strings);
-  Opts.MicrosoftExt = Args.hasArg(OPT_fms_extensions);
+  Opts.MicrosoftExt
+    = Args.hasArg(OPT_fms_extensions) || Args.hasArg(OPT_fms_compatibility);
   Opts.MicrosoftMode = Args.hasArg(OPT_fms_compatibility);
   Opts.MSCVersion = Args.getLastArgIntValue(OPT_fmsc_version, 0, Diags);
   Opts.Borland = Args.hasArg(OPT_fborland_extensions);
diff --git a/test/Lexer/ms-extensions.c b/test/Lexer/ms-extensions.c
index 9cd868e..377d2d5 100644
--- a/test/Lexer/ms-extensions.c
+++ b/test/Lexer/ms-extensions.c
@@ -1,4 +1,5 @@
 // RUN: %clang_cc1 -fsyntax-only -verify -fms-extensions %s
+// RUN: %clang_cc1 -fsyntax-only -verify -fms-compatibility %s
 
 __int8 x1  = 3i8;
 __int16 x2 = 4i16;