diff --git a/clang/lib/Frontend/InitPreprocessor.cpp b/clang/lib/Frontend/InitPreprocessor.cpp
index 9428cd5..77a1b3f 100644
--- a/clang/lib/Frontend/InitPreprocessor.cpp
+++ b/clang/lib/Frontend/InitPreprocessor.cpp
@@ -554,6 +554,9 @@
   if (!TargetInfo::isTypeSigned(TI.getWIntType()))
     Builder.defineMacro("__WINT_UNSIGNED__");
 
+  if (!TargetInfo::isTypeSigned(TI.getWCharType()))
+    Builder.defineMacro("__WCHAR_UNSIGNED__");
+
   // Define exact-width integer types for stdint.h
   Builder.defineMacro("__INT" + llvm::Twine(TI.getCharWidth()) + "_TYPE__",
                       "char");