diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 7e7bd25..1e07e76 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -96,6 +96,7 @@
   PARSE_LANGOPT_IMPORTANT(AltiVec, diag::warn_pch_altivec);
   PARSE_LANGOPT_IMPORTANT(Exceptions, diag::warn_pch_exceptions);
   PARSE_LANGOPT_IMPORTANT(SjLjExceptions, diag::warn_pch_sjlj_exceptions);
+  PARSE_LANGOPT_IMPORTANT(MSBitfields, diag::warn_pch_ms_bitfields);
   PARSE_LANGOPT_IMPORTANT(NeXTRuntime, diag::warn_pch_objc_runtime);
   PARSE_LANGOPT_IMPORTANT(Freestanding, diag::warn_pch_freestanding);
   PARSE_LANGOPT_IMPORTANT(NoBuiltin, diag::warn_pch_builtins);
@@ -2613,6 +2614,7 @@
     PARSE_LANGOPT(AltiVec);
     PARSE_LANGOPT(Exceptions);
     PARSE_LANGOPT(SjLjExceptions);
+    PARSE_LANGOPT(MSBitfields);
     PARSE_LANGOPT(NeXTRuntime);
     PARSE_LANGOPT(Freestanding);
     PARSE_LANGOPT(NoBuiltin);
diff --git a/lib/Serialization/ASTWriter.cpp b/lib/Serialization/ASTWriter.cpp
index e906407..b85aac1 100644
--- a/lib/Serialization/ASTWriter.cpp
+++ b/lib/Serialization/ASTWriter.cpp
@@ -911,6 +911,7 @@
   Record.push_back(LangOpts.Exceptions);  // Support exception handling.
   Record.push_back(LangOpts.SjLjExceptions);
 
+  Record.push_back(LangOpts.MSBitfields); // MS-compatible structure layout
   Record.push_back(LangOpts.NeXTRuntime); // Use NeXT runtime.
   Record.push_back(LangOpts.Freestanding); // Freestanding implementation
   Record.push_back(LangOpts.NoBuiltin); // Do not use builtin functions (-fno-builtin)