Index: include/clang/Lex/Preprocessor.h
===================================================================
--- include/clang/Lex/Preprocessor.h
+++ include/clang/Lex/Preprocessor.h
@@ -939,11 +939,11 @@
   void setPredefines(const char *P) { Predefines = P; }
   void setPredefines(StringRef P) { Predefines = P; }
 
-  /// Return information about the specified preprocessor
-  /// identifier token.
-  IdentifierInfo *getIdentifierInfo(StringRef Name) const {
-    return &Identifiers.get(Name);
-  }
+  /// Return information about the specified preprocessor identifier token.
+  /// If \p CheckOutOfDate is true, then the returned information is ensured
+  /// to be not out of date.
+  IdentifierInfo *getIdentifierInfo(StringRef Name,
+                                    bool CheckOutOfDate = true) const;
 
   /// \brief Add the specified pragma handler to this preprocessor.
   ///
Index: lib/Lex/Preprocessor.cpp
===================================================================
--- lib/Lex/Preprocessor.cpp
+++ lib/Lex/Preprocessor.cpp
@@ -245,6 +245,27 @@
   llvm::errs() << ">";
 }
 
+IdentifierInfo *Preprocessor::getIdentifierInfo(StringRef Name,
+                                                bool CheckOutOfDate) const {
+  IdentifierInfo &II = Identifiers.get(Name);
+  // If the information about this identifier is out of date, update it from
+  // the external source.
+  // We have to treat __VA_ARGS__ in a special way, since it gets
+  // serialized with isPoisoned = true, but our preprocessor may have
+  // unpoisoned it if we're defining a C99 macro.
+  if (CheckOutOfDate && II.isOutOfDate()) {
+    bool CurrentIsPoisoned = false;
+    if (&II == Ident__VA_ARGS__)
+      CurrentIsPoisoned = Ident__VA_ARGS__->isPoisoned();
+
+    updateOutOfDateIdentifier(II);
+
+    if (&II == Ident__VA_ARGS__)
+      II.setIsPoisoned(CurrentIsPoisoned);
+  }
+  return &II;
+}
+
 void Preprocessor::DumpLocation(SourceLocation Loc) const {
   Loc.dump(SourceMgr);
 }
@@ -646,23 +667,8 @@
 
   IdentifierInfo &II = *Identifier.getIdentifierInfo();
 
-  // If the information about this identifier is out of date, update it from
-  // the external source.
-  // We have to treat __VA_ARGS__ in a special way, since it gets
-  // serialized with isPoisoned = true, but our preprocessor may have
-  // unpoisoned it if we're defining a C99 macro.
-  if (II.isOutOfDate()) {
-    bool CurrentIsPoisoned = false;
-    if (&II == Ident__VA_ARGS__)
-      CurrentIsPoisoned = Ident__VA_ARGS__->isPoisoned();
-
-    updateOutOfDateIdentifier(II);
-    Identifier.setKind(II.getTokenID());
+  Identifier.setKind(II.getTokenID());
 
-    if (&II == Ident__VA_ARGS__)
-      II.setIsPoisoned(CurrentIsPoisoned);
-  }
-  
   // If this identifier was poisoned, and if it was not produced from a macro
   // expansion, emit an error.
   if (II.isPoisoned() && CurPPLexer) {