1 files changed, 8 insertions, 1 deletions
diff --git a/clang/lib/Lex/PPDirectives.cpp b/clang/lib/Lex/PPDirectives.cpp
index 748bc38054d..8988e48af55 100644
--- a/clang/lib/Lex/PPDirectives.cpp
+++ b/clang/lib/Lex/PPDirectives.cpp
@@ -120,8 +120,15 @@ void Preprocessor::ReadMacroName(Token &MacroNameTok, char isDefineUndef) {
     std::string Spelling = getSpelling(MacroNameTok, &Invalid);
     if (Invalid)
       return;
-    
+
     const IdentifierInfo &Info = Identifiers.get(Spelling);
+
+    // Allow #defining |and| and friends in microsoft mode.
+    if (Info.isCPlusPlusOperatorKeyword() && getLangOptions().MicrosoftExt) {
+      MacroNameTok.setIdentifierInfo(getIdentifierInfo(Spelling));
+      return;
+    }
+
     if (Info.isCPlusPlusOperatorKeyword())
       // C++ 2.5p2: Alternative tokens behave the same as its primary token
       // except for their spellings.