diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -1647,6 +1647,7 @@
   /// Only common bits are stored here. Additional uncommon bits are stored
   /// in a trailing object after FunctionProtoType.
   class FunctionTypeBitfields {
+    friend class FunctionNoProtoType;
     friend class FunctionProtoType;
     friend class FunctionType;
 
@@ -3926,7 +3927,9 @@
                      Result->getDependence() &
                          ~(TypeDependence::DependentInstantiation |
                            TypeDependence::UnexpandedPack),
-                     Info) {}
+                     Info) {
+    FunctionTypeBits.FastTypeQuals = 0;
+  }
 
 public:
   // No additional state past what FunctionType provides.