diff --git a/clang/include/clang/Basic/AttributeCommonInfo.h b/clang/include/clang/Basic/AttributeCommonInfo.h
index 7dc05418498d0..908e0c7154427 100644
--- a/clang/include/clang/Basic/AttributeCommonInfo.h
+++ b/clang/include/clang/Basic/AttributeCommonInfo.h
@@ -74,11 +74,16 @@ class AttributeCommonInfo {
   SourceRange AttrRange;
   const SourceLocation ScopeLoc;
   // Corresponds to the Kind enum.
+  LLVM_PREFERRED_TYPE(Kind)
   unsigned AttrKind : 16;
   /// Corresponds to the Syntax enum.
+  LLVM_PREFERRED_TYPE(Syntax)
   unsigned SyntaxUsed : 4;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned SpellingIndex : 4;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsAlignas : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsRegularKeywordAttribute : 1;
 
 protected:
@@ -123,9 +128,12 @@ class AttributeCommonInfo {
         : SyntaxUsed(SyntaxUsed), SpellingIndex(SpellingNotCalculated),
           IsAlignas(0), IsRegularKeywordAttribute(0) {}
 
+    LLVM_PREFERRED_TYPE(Syntax)
     unsigned SyntaxUsed : 4;
     unsigned SpellingIndex : 4;
+    LLVM_PREFERRED_TYPE(bool)
     unsigned IsAlignas : 1;
+    LLVM_PREFERRED_TYPE(bool)
     unsigned IsRegularKeywordAttribute : 1;
   };
 
diff --git a/clang/include/clang/Basic/Diagnostic.h b/clang/include/clang/Basic/Diagnostic.h
index 3df037b793b39..0c7836c2ea569 100644
--- a/clang/include/clang/Basic/Diagnostic.h
+++ b/clang/include/clang/Basic/Diagnostic.h
@@ -314,18 +314,23 @@ class DiagnosticsEngine : public RefCountedBase<DiagnosticsEngine> {
     // "Global" configuration state that can actually vary between modules.
 
     // Ignore all warnings: -w
+    LLVM_PREFERRED_TYPE(bool)
     unsigned IgnoreAllWarnings : 1;
 
     // Enable all warnings.
+    LLVM_PREFERRED_TYPE(bool)
     unsigned EnableAllWarnings : 1;
 
     // Treat warnings like errors.
+    LLVM_PREFERRED_TYPE(bool)
     unsigned WarningsAsErrors : 1;
 
     // Treat errors like fatal errors.
+    LLVM_PREFERRED_TYPE(bool)
     unsigned ErrorsAsFatal : 1;
 
     // Suppress warnings in system headers.
+    LLVM_PREFERRED_TYPE(bool)
     unsigned SuppressSystemWarnings : 1;
 
     // Map extensions to warnings or errors?
@@ -1822,12 +1827,17 @@ class ForwardingDiagnosticConsumer : public DiagnosticConsumer {
 struct TemplateDiffTypes {
   intptr_t FromType;
   intptr_t ToType;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned PrintTree : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned PrintFromType : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned ElideType : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned ShowColors : 1;
 
   // The printer sets this variable to true if the template diff was used.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned TemplateDiffUsed : 1;
 };
 
diff --git a/clang/include/clang/Basic/DiagnosticIDs.h b/clang/include/clang/Basic/DiagnosticIDs.h
index 06ef1c6904c31..0cdda42793f6f 100644
--- a/clang/include/clang/Basic/DiagnosticIDs.h
+++ b/clang/include/clang/Basic/DiagnosticIDs.h
@@ -100,11 +100,17 @@ namespace clang {
   }
 
 class DiagnosticMapping {
+  LLVM_PREFERRED_TYPE(diag::Severity)
   unsigned Severity : 3;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsUser : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsPragma : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasNoWarningAsError : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasNoErrorAsFatal : 1;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned WasUpgradedFromWarning : 1;
 
 public:
diff --git a/clang/include/clang/Basic/Module.h b/clang/include/clang/Basic/Module.h
index 6a7423938bdb8..239eb5a637f3e 100644
--- a/clang/include/clang/Basic/Module.h
+++ b/clang/include/clang/Basic/Module.h
@@ -298,50 +298,62 @@ class alignas(8) Module {
   /// Whether this module has declared itself unimportable, either because
   /// it's missing a requirement from \p Requirements or because it's been
   /// shadowed by another module.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsUnimportable : 1;
 
   /// Whether we tried and failed to load a module file for this module.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasIncompatibleModuleFile : 1;
 
   /// Whether this module is available in the current translation unit.
   ///
   /// If the module is missing headers or does not meet all requirements then
   /// this bit will be 0.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsAvailable : 1;
 
   /// Whether this module was loaded from a module file.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsFromModuleFile : 1;
 
   /// Whether this is a framework module.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsFramework : 1;
 
   /// Whether this is an explicit submodule.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsExplicit : 1;
 
   /// Whether this is a "system" module (which assumes that all
   /// headers in it are system headers).
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsSystem : 1;
 
   /// Whether this is an 'extern "C"' module (which implicitly puts all
   /// headers in it within an 'extern "C"' block, and allows the module to be
   /// imported within such a block).
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsExternC : 1;
 
   /// Whether this is an inferred submodule (module * { ... }).
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsInferred : 1;
 
   /// Whether we should infer submodules for this module based on
   /// the headers.
   ///
   /// Submodules can only be inferred for modules with an umbrella header.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned InferSubmodules : 1;
 
   /// Whether, when inferring submodules, the inferred submodules
   /// should be explicit.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned InferExplicitSubmodules : 1;
 
   /// Whether, when inferring submodules, the inferr submodules should
   /// export all modules they import (e.g., the equivalent of "export *").
+  LLVM_PREFERRED_TYPE(bool)
   unsigned InferExportWildcard : 1;
 
   /// Whether the set of configuration macros is exhaustive.
@@ -349,18 +361,22 @@ class alignas(8) Module {
   /// When the set of configuration macros is exhaustive, meaning
   /// that no identifier not in this list should affect how the module is
   /// built.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned ConfigMacrosExhaustive : 1;
 
   /// Whether files in this module can only include non-modular headers
   /// and headers from used modules.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned NoUndeclaredIncludes : 1;
 
   /// Whether this module came from a "private" module map, found next
   /// to a regular (public) module map.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned ModuleMapIsPrivate : 1;
 
   /// Whether this C++20 named modules doesn't need an initializer.
   /// This is only meaningful for C++20 modules.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned NamedModuleHasInit : 1;
 
   /// Describes the visibility of the various names within a
diff --git a/clang/include/clang/Basic/ParsedAttrInfo.h b/clang/include/clang/Basic/ParsedAttrInfo.h
index 3950d484ffd32..537d8f3391d58 100644
--- a/clang/include/clang/Basic/ParsedAttrInfo.h
+++ b/clang/include/clang/Basic/ParsedAttrInfo.h
@@ -33,6 +33,7 @@ class TargetInfo;
 
 struct ParsedAttrInfo {
   /// Corresponds to the Kind enum.
+  LLVM_PREFERRED_TYPE(AttributeCommonInfo::Kind)
   unsigned AttrKind : 16;
   /// The number of required arguments of this attribute.
   unsigned NumArgs : 4;
@@ -41,18 +42,25 @@ struct ParsedAttrInfo {
   /// The number of non-fake arguments specified in the attribute definition.
   unsigned NumArgMembers : 4;
   /// True if the parsing does not match the semantic content.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasCustomParsing : 1;
   // True if this attribute accepts expression parameter pack expansions.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned AcceptsExprPack : 1;
   /// True if this attribute is only available for certain targets.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsTargetSpecific : 1;
   /// True if this attribute applies to types.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsType : 1;
   /// True if this attribute applies to statements.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsStmt : 1;
   /// True if this attribute has any spellings that are known to gcc.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsKnownToGCC : 1;
   /// True if this attribute is supported by #pragma clang attribute.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsSupportedByPragmaAttribute : 1;
   /// The syntaxes supported by this attribute and how they're spelled.
   struct Spelling {
diff --git a/clang/include/clang/Basic/SourceManager.h b/clang/include/clang/Basic/SourceManager.h
index 420fda111ad13..985ea6354b821 100644
--- a/clang/include/clang/Basic/SourceManager.h
+++ b/clang/include/clang/Basic/SourceManager.h
@@ -167,17 +167,21 @@ class alignas(8) ContentCache {
   ///
   /// When true, the original entry may be a virtual file that does not
   /// exist.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned BufferOverridden : 1;
 
   /// True if this content cache was initially created for a source file
   /// considered to be volatile (likely to change between stat and open).
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsFileVolatile : 1;
 
   /// True if this file may be transient, that is, if it might not
   /// exist at some later point in time when this content entry is used,
   /// after serialization and deserialization.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsTransient : 1;
 
+  LLVM_PREFERRED_TYPE(bool)
   mutable unsigned IsBufferInvalid : 1;
 
   ContentCache()
@@ -305,6 +309,7 @@ class FileInfo {
   unsigned NumCreatedFIDs : 31;
 
   /// Whether this FileInfo has any \#line directives.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasLineDirectives : 1;
 
   /// The content cache and the characteristic of the file.
@@ -476,6 +481,7 @@ static_assert(sizeof(FileInfo) <= sizeof(ExpansionInfo),
 class SLocEntry {
   static constexpr int OffsetBits = 8 * sizeof(SourceLocation::UIntTy) - 1;
   SourceLocation::UIntTy Offset : OffsetBits;
+  LLVM_PREFERRED_TYPE(bool)
   SourceLocation::UIntTy IsExpansion : 1;
   union {
     FileInfo File;
diff --git a/clang/include/clang/Basic/Specifiers.h b/clang/include/clang/Basic/Specifiers.h
index 0add24d53b21e..87f29c8ae10bd 100644
--- a/clang/include/clang/Basic/Specifiers.h
+++ b/clang/include/clang/Basic/Specifiers.h
@@ -103,9 +103,13 @@ namespace clang {
   /// were written in a particular type specifier sequence.
   struct WrittenBuiltinSpecs {
     static_assert(TST_error < 1 << 7, "Type bitfield not wide enough for TST");
-    /*DeclSpec::TST*/ unsigned Type : 7;
-    /*DeclSpec::TSS*/ unsigned Sign  : 2;
-    /*TypeSpecifierWidth*/ unsigned Width : 2;
+    LLVM_PREFERRED_TYPE(TypeSpecifierType)
+    unsigned Type : 7;
+    LLVM_PREFERRED_TYPE(TypeSpecifierSign)
+    unsigned Sign : 2;
+    LLVM_PREFERRED_TYPE(TypeSpecifierWidth)
+    unsigned Width : 2;
+    LLVM_PREFERRED_TYPE(bool)
     unsigned ModeAttr : 1;
   };
 
diff --git a/clang/include/clang/Basic/TargetInfo.h b/clang/include/clang/Basic/TargetInfo.h
index b3c5cbfb319f0..41f3c2e403cbe 100644
--- a/clang/include/clang/Basic/TargetInfo.h
+++ b/clang/include/clang/Basic/TargetInfo.h
@@ -156,6 +156,7 @@ struct TransferrableTargetInfo {
   ///
   /// Otherwise, when this flag is not set, the normal built-in boolean type is
   /// used.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned UseSignedCharForObjCBool : 1;
 
   /// Control whether the alignment of bit-field types is respected when laying
@@ -163,6 +164,7 @@ struct TransferrableTargetInfo {
   /// used to (a) impact the alignment of the containing structure, and (b)
   /// ensure that the individual bit-field will not straddle an alignment
   /// boundary.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned UseBitFieldTypeAlignment : 1;
 
   /// Whether zero length bitfields (e.g., int : 0;) force alignment of
@@ -171,13 +173,16 @@ struct TransferrableTargetInfo {
   /// If the alignment of the zero length bitfield is greater than the member
   /// that follows it, `bar', `bar' will be aligned as the type of the
   /// zero-length bitfield.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned UseZeroLengthBitfieldAlignment : 1;
 
   /// Whether zero length bitfield alignment is respected if they are the
   /// leading members.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned UseLeadingZeroLengthBitfield : 1;
 
   ///  Whether explicit bit field alignment attributes are honored.
+  LLVM_PREFERRED_TYPE(bool)
   unsigned UseExplicitBitFieldAlignment : 1;
 
   /// If non-zero, specifies a fixed alignment value for bitfields that follow
@@ -239,20 +244,29 @@ class TargetInfo : public TransferrableTargetInfo,
   mutable StringRef PlatformName;
   mutable VersionTuple PlatformMinVersion;
 
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasAlignMac68kSupport : 1;
+  LLVM_PREFERRED_TYPE(FloatModeKind)
   unsigned RealTypeUsesObjCFPRetMask : llvm::BitWidth<FloatModeKind>;
+  LLVM_PREFERRED_TYPE(bool)
   unsigned ComplexLongDoubleUsesFP2Ret : 1;
 
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasBuiltinMSVaList : 1;
 
+  LLVM_PREFERRED_TYPE(bool)
   unsigned IsRenderScriptTarget : 1;
 
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasAArch64SVETypes : 1;
 
+  LLVM_PREFERRED_TYPE(bool)
   unsigned HasRISCVVTypes : 1;
 
+  LLVM_PREFERRED_TYPE(bool)
   unsigned AllowAMDGPUUnsafeFPAtomics : 1;
 
+  LLVM_PREFERRED_TYPE(bool)
   unsigned ARMCDECoprocMask : 8;
 
   unsigned MaxOpenCLWorkGroupSize;