diff --git a/lib/CodeGen/Mangle.cpp b/lib/CodeGen/Mangle.cpp
index fd77274..344ef06 100644
--- a/lib/CodeGen/Mangle.cpp
+++ b/lib/CodeGen/Mangle.cpp
@@ -705,7 +705,7 @@
   // Only operate on the canonical type!
   T = Context.getASTContext().getCanonicalType(T);
 
-  bool IsSubstitutable = !isa<BuiltinType>(T);
+  bool IsSubstitutable = T.hasQualifiers() || !isa<BuiltinType>(T);
   if (IsSubstitutable && mangleSubstitution(T))
     return;