diff --git a/clang/include/clang/AST/Attr.h b/clang/include/clang/AST/Attr.h
index 8884bd5a90de1..1b831c9511e27 100644
--- a/clang/include/clang/AST/Attr.h
+++ b/clang/include/clang/AST/Attr.h
@@ -40,17 +40,23 @@ class OMPTraitInfo;
 /// Attr - This represents one attribute.
 class Attr : public AttributeCommonInfo {
 private:
+  LLVM_PREFERRED_TYPE(attr::Kind)
   unsigned AttrKind : 16;
 
 protected:
   /// An index into the spelling list of an
   /// attribute defined in Attr.td file.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned Inherited : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsPackExpansion : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned Implicit : 1;
   // FIXME: These are properties of the attribute kind, not state for this
   // instance of the attribute.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsLateParsed : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned InheritEvenIfAlreadyPresent : 1;
 
   void *operator new(size_t bytes) noexcept {
@@ -243,7 +249,9 @@ class ParameterABIAttr : public InheritableParamAttr {
 class ParamIdx {
   // Idx is exposed only via accessors that specify specific encodings.
   unsigned Idx : 30;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasThis : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsValid : 1;
 
   void assertComparable(const ParamIdx &I) const {