Index: cfe/trunk/include/clang/Basic/DiagnosticGroups.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticGroups.td
+++ cfe/trunk/include/clang/Basic/DiagnosticGroups.td
@@ -515,8 +515,13 @@
 def Uninitialized  : DiagGroup<"uninitialized", [UninitializedSometimes,
                                                  UninitializedStaticSelfInit]>;
 def IgnoredPragmaIntrinsic : DiagGroup<"ignored-pragma-intrinsic">;
+// #pragma optimize is often used to avoid to work around MSVC codegen bugs or
+// to disable inlining. It's not completely clear what alternative to suggest
+// (#pragma clang optimize, noinline) so suggest nothing for now.
+def IgnoredPragmaOptimize : DiagGroup<"ignored-pragma-optimize">;
 def UnknownPragmas : DiagGroup<"unknown-pragmas">;
-def IgnoredPragmas : DiagGroup<"ignored-pragmas", [IgnoredPragmaIntrinsic]>;
+def IgnoredPragmas : DiagGroup<"ignored-pragmas",
+    [IgnoredPragmaIntrinsic, IgnoredPragmaOptimize]>;
 def PragmaClangAttribute : DiagGroup<"pragma-clang-attribute">;
 def PragmaPackSuspiciousInclude : DiagGroup<"pragma-pack-suspicious-include">;
 def PragmaPack : DiagGroup<"pragma-pack", [PragmaPackSuspiciousInclude]>;
Index: cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
===================================================================
--- cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
+++ cfe/trunk/include/clang/Basic/DiagnosticParseKinds.td
@@ -895,6 +895,12 @@
   "missing ')' after '#pragma %0' - ignoring">, InGroup<IgnoredPragmas>;
 def warn_pragma_expected_identifier : Warning<
   "expected identifier in '#pragma %0' - ignored">, InGroup<IgnoredPragmas>;
+def warn_pragma_expected_string : Warning<
+  "expected string literal in '#pragma %0' - ignoring">, InGroup<IgnoredPragmas>;
+def warn_pragma_missing_argument : Warning<
+  "missing argument to '#pragma %0'%select{|; expected %2}1">, InGroup<IgnoredPragmas>;
+def warn_pragma_invalid_argument : Warning<
+  "unexpected argument '%0' to '#pragma %1'%select{|; expected %3}2">, InGroup<IgnoredPragmas>;
 
 // '#pragma clang section' related errors
 def err_pragma_expected_clang_section_name : Error<
@@ -923,6 +929,8 @@
 def warn_pragma_extra_tokens_at_eol : Warning<
   "extra tokens at end of '#pragma %0' - ignored">,
   InGroup<IgnoredPragmas>;
+def warn_pragma_expected_comma : Warning<
+  "expected ',' in '#pragma %0'">, InGroup<IgnoredPragmas>;
 def warn_pragma_expected_punc : Warning<
   "expected ')' or ',' in '#pragma %0'">, InGroup<IgnoredPragmas>;
 def warn_pragma_expected_non_wide_string : Warning<
@@ -960,6 +968,10 @@
 def warn_pragma_intrinsic_builtin : Warning<
   "%0 is not a recognized builtin%select{|; consider including <intrin.h> to access non-builtin intrinsics}1">,
   InGroup<IgnoredPragmaIntrinsic>;
+// - #pragma optimize
+def warn_pragma_optimize : Warning<
+  "'#pragma optimize' is not supported">,
+  InGroup<IgnoredPragmaOptimize>;
 // - #pragma unused
 def warn_pragma_unused_expected_var : Warning<
   "expected '#pragma unused' argument to be a variable name">,
Index: cfe/trunk/include/clang/Parse/Parser.h
===================================================================
--- cfe/trunk/include/clang/Parse/Parser.h
+++ cfe/trunk/include/clang/Parse/Parser.h
@@ -179,6 +179,7 @@
   std::unique_ptr<PragmaHandler> MSSection;
   std::unique_ptr<PragmaHandler> MSRuntimeChecks;
   std::unique_ptr<PragmaHandler> MSIntrinsic;
+  std::unique_ptr<PragmaHandler> MSOptimize;
   std::unique_ptr<PragmaHandler> CUDAForceHostDeviceHandler;
   std::unique_ptr<PragmaHandler> OptimizeHandler;
   std::unique_ptr<PragmaHandler> LoopHintHandler;
Index: cfe/trunk/lib/Parse/ParsePragma.cpp
===================================================================
--- cfe/trunk/lib/Parse/ParsePragma.cpp
+++ cfe/trunk/lib/Parse/ParsePragma.cpp
@@ -220,6 +220,12 @@
                     Token &FirstToken) override;
 };
 
+struct PragmaMSOptimizeHandler : public PragmaHandler {
+  PragmaMSOptimizeHandler() : PragmaHandler("optimize") {}
+  void HandlePragma(Preprocessor &PP, PragmaIntroducerKind Introducer,
+                    Token &FirstToken) override;
+};
+
 struct PragmaForceCUDAHostDeviceHandler : public PragmaHandler {
   PragmaForceCUDAHostDeviceHandler(Sema &Actions)
       : PragmaHandler("force_cuda_host_device"), Actions(Actions) {}
@@ -324,6 +330,8 @@
     PP.AddPragmaHandler(MSRuntimeChecks.get());
     MSIntrinsic.reset(new PragmaMSIntrinsicHandler());
     PP.AddPragmaHandler(MSIntrinsic.get());
+    MSOptimize.reset(new PragmaMSOptimizeHandler());
+    PP.AddPragmaHandler(MSOptimize.get());
   }
 
   if (getLangOpts().CUDA) {
@@ -410,6 +418,8 @@
     MSRuntimeChecks.reset();
     PP.RemovePragmaHandler(MSIntrinsic.get());
     MSIntrinsic.reset();
+    PP.RemovePragmaHandler(MSOptimize.get());
+    MSOptimize.reset();
   }
 
   if (getLangOpts().CUDA) {
@@ -2949,6 +2959,61 @@
     PP.Diag(Tok.getLocation(), diag::warn_pragma_extra_tokens_at_eol)
         << "intrinsic";
 }
+
+// #pragma optimize("gsty", on|off)
+void PragmaMSOptimizeHandler::HandlePragma(Preprocessor &PP,
+                                           PragmaIntroducerKind Introducer,
+                                           Token &Tok) {
+  SourceLocation StartLoc = Tok.getLocation();
+  PP.Lex(Tok);
+
+  if (Tok.isNot(tok::l_paren)) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_expected_lparen) << "optimize";
+    return;
+  }
+  PP.Lex(Tok);
+
+  if (Tok.isNot(tok::string_literal)) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_expected_string) << "optimize";
+    return;
+  }
+  // We could syntax check the string but it's probably not worth the effort.
+  PP.Lex(Tok);
+
+  if (Tok.isNot(tok::comma)) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_expected_comma) << "optimize";
+    return;
+  }
+  PP.Lex(Tok);
+
+  if (Tok.is(tok::eod) || Tok.is(tok::r_paren)) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_missing_argument)
+        << "optimize" << /*Expected=*/true << "'on' or 'off'";
+    return;
+  }
+  IdentifierInfo *II = Tok.getIdentifierInfo();
+  if (!II || (!II->isStr("on") && !II->isStr("off"))) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_invalid_argument)
+        << PP.getSpelling(Tok) << "optimize" << /*Expected=*/true
+        << "'on' or 'off'";
+    return;
+  }
+  PP.Lex(Tok);
+
+  if (Tok.isNot(tok::r_paren)) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_expected_rparen) << "optimize";
+    return;
+  }
+  PP.Lex(Tok);
+
+  if (Tok.isNot(tok::eod)) {
+    PP.Diag(Tok.getLocation(), diag::warn_pragma_extra_tokens_at_eol)
+        << "optimize";
+    return;
+  }
+  PP.Diag(StartLoc, diag::warn_pragma_optimize);
+}
+
 void PragmaForceCUDAHostDeviceHandler::HandlePragma(
     Preprocessor &PP, PragmaIntroducerKind Introducer, Token &Tok) {
   Token FirstTok = Tok;
Index: cfe/trunk/test/Preprocessor/pragma_microsoft.c
===================================================================
--- cfe/trunk/test/Preprocessor/pragma_microsoft.c
+++ cfe/trunk/test/Preprocessor/pragma_microsoft.c
@@ -190,3 +190,11 @@
 #pragma intrinsic(asdf) // no-warning
 #pragma clang diagnostic pop
 #pragma intrinsic(asdf) // expected-warning {{'asdf' is not a recognized builtin; consider including <intrin.h>}}
+
+#pragma optimize          // expected-warning{{missing '(' after '#pragma optimize'}}
+#pragma optimize(         // expected-warning{{expected string literal in '#pragma optimize'}}
+#pragma optimize(a        // expected-warning{{expected string literal in '#pragma optimize'}}
+#pragma optimize("g"      // expected-warning{{expected ',' in '#pragma optimize'}}
+#pragma optimize("g",     // expected-warning{{missing argument to '#pragma optimize'; expected 'on' or 'off'}}
+#pragma optimize("g",xyz  // expected-warning{{unexpected argument 'xyz' to '#pragma optimize'; expected 'on' or 'off'}}
+#pragma optimize("g",on)  // expected-warning{{#pragma optimize' is not supported}}