diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
index 10916053cdfbf..5f7c5b86892d0 100644
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -1689,7 +1689,10 @@ class alignas(TypeAlignment) Type : public ExtQualsTypeCommonBase {
 
     /// Whether we have a stored size expression.
     LLVM_PREFERRED_TYPE(bool)
-    unsigned HasStoredSizeExpr : 1;
+    unsigned HasExternalSize : 1;
+
+    LLVM_PREFERRED_TYPE(unsigned)
+    unsigned SizeWidth : 5;
   };
 
   class BuiltinTypeBitfields {
@@ -3181,35 +3184,93 @@ class ArrayType : public Type, public llvm::FoldingSetNode {
 /// Represents the canonical version of C arrays with a specified constant size.
 /// For example, the canonical type for 'int A[4 + 4*100]' is a
 /// ConstantArrayType where the element type is 'int' and the size is 404.
-class ConstantArrayType final
-    : public ArrayType,
-      private llvm::TrailingObjects<ConstantArrayType, const Expr *> {
+class ConstantArrayType final : public ArrayType {
   friend class ASTContext; // ASTContext creates these.
-  friend TrailingObjects;
 
-  llvm::APInt Size; // Allows us to unique the type.
+  struct ExternalSize {
+    ExternalSize(const llvm::APInt &Sz, const Expr *SE)
+        : Size(Sz), SizeExpr(SE) {}
+    llvm::APInt Size; // Allows us to unique the type.
+    const Expr *SizeExpr;
+  };
 
-  ConstantArrayType(QualType et, QualType can, const llvm::APInt &size,
-                    const Expr *sz, ArraySizeModifier sm, unsigned tq)
-      : ArrayType(ConstantArray, et, can, sm, tq, sz), Size(size) {
-    ConstantArrayTypeBits.HasStoredSizeExpr = sz != nullptr;
-    if (ConstantArrayTypeBits.HasStoredSizeExpr) {
-      assert(!can.isNull() && "canonical constant array should not have size");
-      *getTrailingObjects<const Expr*>() = sz;
-    }
+  union {
+    uint64_t Size;
+    ExternalSize *SizePtr;
+  };
+
+  ConstantArrayType(QualType Et, QualType Can, uint64_t Width, uint64_t Sz,
+                    ArraySizeModifier SM, unsigned TQ)
+      : ArrayType(ConstantArray, Et, Can, SM, TQ, nullptr), Size(Sz) {
+    ConstantArrayTypeBits.HasExternalSize = false;
+    ConstantArrayTypeBits.SizeWidth = Width / 8;
+    // The in-structure size stores the size in bytes rather than bits so we
+    // drop the three least significant bits since they're always zero anyways.
+    assert(Width < 0xFF && "Type width in bits must be less than 8 bits");
   }
 
-  unsigned numTrailingObjects(OverloadToken<const Expr*>) const {
-    return ConstantArrayTypeBits.HasStoredSizeExpr;
+  ConstantArrayType(QualType Et, QualType Can, ExternalSize *SzPtr,
+                    ArraySizeModifier SM, unsigned TQ)
+      : ArrayType(ConstantArray, Et, Can, SM, TQ, SzPtr->SizeExpr),
+        SizePtr(SzPtr) {
+    ConstantArrayTypeBits.HasExternalSize = true;
+    ConstantArrayTypeBits.SizeWidth = 0;
+
+    assert((SzPtr->SizeExpr == nullptr || !Can.isNull()) &&
+           "canonical constant array should not have size expression");
   }
 
+  static ConstantArrayType *Create(const ASTContext &Ctx, QualType ET,
+                                   QualType Can, const llvm::APInt &Sz,
+                                   const Expr *SzExpr, ArraySizeModifier SzMod,
+                                   unsigned Qual);
+
 public:
-  const llvm::APInt &getSize() const { return Size; }
+  /// Return the constant array size as an APInt.
+  llvm::APInt getSize() const {
+    return ConstantArrayTypeBits.HasExternalSize
+               ? SizePtr->Size
+               : llvm::APInt(ConstantArrayTypeBits.SizeWidth * 8, Size);
+  }
+
+  /// Return the bit width of the size type.
+  unsigned getSizeBitWidth() const {
+    return ConstantArrayTypeBits.HasExternalSize
+               ? SizePtr->Size.getBitWidth()
+               : static_cast<unsigned>(ConstantArrayTypeBits.SizeWidth * 8);
+  }
+
+  /// Return true if the size is zero.
+  bool isZeroSize() const {
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->Size.isZero()
+                                                 : 0 == Size;
+  }
+
+  /// Return the size zero-extended as a uint64_t.
+  uint64_t getZExtSize() const {
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->Size.getZExtValue()
+                                                 : Size;
+  }
+
+  /// Return the size sign-extended as a uint64_t.
+  int64_t getSExtSize() const {
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->Size.getSExtValue()
+                                                 : static_cast<int64_t>(Size);
+  }
+
+  /// Return the size zero-extended to uint64_t or UINT64_MAX if the value is
+  /// larger than UINT64_MAX.
+  uint64_t getLimitedSize() const {
+    return ConstantArrayTypeBits.HasExternalSize
+               ? SizePtr->Size.getLimitedValue()
+               : Size;
+  }
+
+  /// Return a pointer to the size expression.
   const Expr *getSizeExpr() const {
-    return ConstantArrayTypeBits.HasStoredSizeExpr
-               ? *getTrailingObjects<const Expr *>()
-               : nullptr;
+    return ConstantArrayTypeBits.HasExternalSize ? SizePtr->SizeExpr : nullptr;
   }
+
   bool isSugared() const { return false; }
   QualType desugar() const { return QualType(this, 0); }
 
@@ -3226,14 +3287,13 @@ class ConstantArrayType final
   static unsigned getMaxSizeBits(const ASTContext &Context);
 
   void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx) {
-    Profile(ID, Ctx, getElementType(), getSize(), getSizeExpr(),
+    Profile(ID, Ctx, getElementType(), getZExtSize(), getSizeExpr(),
             getSizeModifier(), getIndexTypeCVRQualifiers());
   }
 
   static void Profile(llvm::FoldingSetNodeID &ID, const ASTContext &Ctx,
-                      QualType ET, const llvm::APInt &ArraySize,
-                      const Expr *SizeExpr, ArraySizeModifier SizeMod,
-                      unsigned TypeQuals);
+                      QualType ET, uint64_t ArraySize, const Expr *SizeExpr,
+                      ArraySizeModifier SizeMod, unsigned TypeQuals);
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == ConstantArray;
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
index 5a8fae76a43a4..7ca341c6cfc32 100644
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -1766,7 +1766,7 @@ TypeInfoChars
 static getConstantArrayInfoInChars(const ASTContext &Context,
                                    const ConstantArrayType *CAT) {
   TypeInfoChars EltInfo = Context.getTypeInfoInChars(CAT->getElementType());
-  uint64_t Size = CAT->getSize().getZExtValue();
+  uint64_t Size = CAT->getZExtSize();
   assert((Size == 0 || static_cast<uint64_t>(EltInfo.Width.getQuantity()) <=
               (uint64_t)(-1)/Size) &&
          "Overflow in array type char size evaluation");
@@ -1910,7 +1910,7 @@ TypeInfo ASTContext::getTypeInfoImpl(const Type *T) const {
     // Model non-constant sized arrays as size zero, but track the alignment.
     uint64_t Size = 0;
     if (const auto *CAT = dyn_cast<ConstantArrayType>(T))
-      Size = CAT->getSize().getZExtValue();
+      Size = CAT->getZExtSize();
 
     TypeInfo EltInfo = getTypeInfo(cast<ArrayType>(T)->getElementType());
     assert((Size == 0 || EltInfo.Width <= (uint64_t)(-1) / Size) &&
@@ -3531,8 +3531,8 @@ QualType ASTContext::getConstantArrayType(QualType EltTy,
   ArySize = ArySize.zextOrTrunc(Target->getMaxPointerWidth());
 
   llvm::FoldingSetNodeID ID;
-  ConstantArrayType::Profile(ID, *this, EltTy, ArySize, SizeExpr, ASM,
-                             IndexTypeQuals);
+  ConstantArrayType::Profile(ID, *this, EltTy, ArySize.getZExtValue(), SizeExpr,
+                             ASM, IndexTypeQuals);
 
   void *InsertPos = nullptr;
   if (ConstantArrayType *ATP =
@@ -3556,11 +3556,8 @@ QualType ASTContext::getConstantArrayType(QualType EltTy,
     assert(!NewIP && "Shouldn't be in the map!"); (void)NewIP;
   }
 
-  void *Mem = Allocate(
-      ConstantArrayType::totalSizeToAlloc<const Expr *>(SizeExpr ? 1 : 0),
-      alignof(ConstantArrayType));
-  auto *New = new (Mem)
-    ConstantArrayType(EltTy, Canon, ArySize, SizeExpr, ASM, IndexTypeQuals);
+  auto *New = ConstantArrayType::Create(*this, EltTy, Canon, ArySize, SizeExpr,
+                                        ASM, IndexTypeQuals);
   ConstantArrayTypes.InsertNode(New, InsertPos);
   Types.push_back(New);
   return QualType(New, 0);
@@ -7022,7 +7019,7 @@ uint64_t
 ASTContext::getConstantArrayElementCount(const ConstantArrayType *CA)  const {
   uint64_t ElementCount = 1;
   do {
-    ElementCount *= CA->getSize().getZExtValue();
+    ElementCount *= CA->getZExtSize();
     CA = dyn_cast_or_null<ConstantArrayType>(
       CA->getElementType()->getAsArrayTypeUnsafe());
   } while (CA);
@@ -8345,7 +8342,7 @@ void ASTContext::getObjCEncodingForTypeImpl(QualType T, std::string &S,
       S += '[';
 
       if (const auto *CAT = dyn_cast<ConstantArrayType>(AT))
-        S += llvm::utostr(CAT->getSize().getZExtValue());
+        S += llvm::utostr(CAT->getZExtSize());
       else {
         //Variable length arrays are encoded as a regular array with 0 elements.
         assert((isa<VariableArrayType>(AT) || isa<IncompleteArrayType>(AT)) &&
@@ -10779,7 +10776,7 @@ QualType ASTContext::mergeTypes(QualType LHS, QualType RHS, bool OfBlockPointer,
   {
     const ConstantArrayType* LCAT = getAsConstantArrayType(LHS);
     const ConstantArrayType* RCAT = getAsConstantArrayType(RHS);
-    if (LCAT && RCAT && RCAT->getSize() != LCAT->getSize())
+    if (LCAT && RCAT && RCAT->getZExtSize() != LCAT->getZExtSize())
       return {};
 
     QualType LHSElem = getAsArrayType(LHS)->getElementType();
diff --git a/clang/lib/AST/Decl.cpp b/clang/lib/AST/Decl.cpp
index 95900afdd2c5d..131f82985e903 100644
--- a/clang/lib/AST/Decl.cpp
+++ b/clang/lib/AST/Decl.cpp
@@ -2840,7 +2840,7 @@ bool VarDecl::hasFlexibleArrayInit(const ASTContext &Ctx) const {
   auto InitTy = Ctx.getAsConstantArrayType(FlexibleInit->getType());
   if (!InitTy)
     return false;
-  return InitTy->getSize() != 0;
+  return !InitTy->isZeroSize();
 }
 
 CharUnits VarDecl::getFlexibleArrayInitChars(const ASTContext &Ctx) const {
diff --git a/clang/lib/AST/ExprConstant.cpp b/clang/lib/AST/ExprConstant.cpp
index 592d43597dc1b..c5bdff0df06b4 100644
--- a/clang/lib/AST/ExprConstant.cpp
+++ b/clang/lib/AST/ExprConstant.cpp
@@ -209,7 +209,7 @@ namespace {
         IsArray = true;
 
         if (auto *CAT = dyn_cast<ConstantArrayType>(AT)) {
-          ArraySize = CAT->getSize().getZExtValue();
+          ArraySize = CAT->getZExtSize();
         } else {
           assert(I == 0 && "unexpected unsized array designator");
           FirstEntryIsUnsizedArray = true;
@@ -401,7 +401,7 @@ namespace {
       // This is a most-derived object.
       MostDerivedType = CAT->getElementType();
       MostDerivedIsArrayElement = true;
-      MostDerivedArraySize = CAT->getSize().getZExtValue();
+      MostDerivedArraySize = CAT->getZExtSize();
       MostDerivedPathLength = Entries.size();
     }
     /// Update this designator to refer to the first element within the array of
@@ -3476,7 +3476,7 @@ static void expandStringLiteral(EvalInfo &Info, const StringLiteral *S,
   QualType CharType = CAT->getElementType();
   assert(CharType->isIntegerType() && "unexpected character type");
 
-  unsigned Elts = CAT->getSize().getZExtValue();
+  unsigned Elts = CAT->getZExtSize();
   Result = APValue(APValue::UninitArray(),
                    std::min(S->getLength(), Elts), Elts);
   APSInt Value(Info.Ctx.getTypeSize(CharType),
@@ -3619,7 +3619,7 @@ static bool CheckArraySize(EvalInfo &Info, const ConstantArrayType *CAT,
                            SourceLocation CallLoc = {}) {
   return Info.CheckArraySize(
       CAT->getSizeExpr() ? CAT->getSizeExpr()->getBeginLoc() : CallLoc,
-      CAT->getNumAddressingBits(Info.Ctx), CAT->getSize().getZExtValue(),
+      CAT->getNumAddressingBits(Info.Ctx), CAT->getZExtSize(),
       /*Diag=*/true);
 }
 
@@ -4908,7 +4908,7 @@ static bool handleDefaultInitValue(QualType T, APValue &Result) {
 
   if (auto *AT =
           dyn_cast_or_null<ConstantArrayType>(T->getAsArrayTypeUnsafe())) {
-    Result = APValue(APValue::UninitArray(), 0, AT->getSize().getZExtValue());
+    Result = APValue(APValue::UninitArray(), 0, AT->getZExtSize());
     if (Result.hasArrayFiller())
       Success &=
           handleDefaultInitValue(AT->getElementType(), Result.getArrayFiller());
@@ -6595,7 +6595,7 @@ static bool HandleDestructionImpl(EvalInfo &Info, SourceRange CallRange,
 
   // For arrays, destroy elements right-to-left.
   if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(T)) {
-    uint64_t Size = CAT->getSize().getZExtValue();
+    uint64_t Size = CAT->getZExtSize();
     QualType ElemT = CAT->getElementType();
 
     if (!CheckArraySize(Info, CAT, CallRange.getBegin()))
@@ -7396,7 +7396,7 @@ class BufferToAPValueConverter {
   }
 
   std::optional<APValue> visit(const ConstantArrayType *Ty, CharUnits Offset) {
-    size_t Size = Ty->getSize().getLimitedValue();
+    size_t Size = Ty->getLimitedSize();
     CharUnits ElementWidth = Info.Ctx.getTypeSizeInChars(Ty->getElementType());
 
     APValue ArrayValue(APValue::UninitArray(), Size, Size);
@@ -9951,7 +9951,7 @@ bool PointerExprEvaluator::VisitCXXNewExpr(const CXXNewExpr *E) {
       assert(CAT && "unexpected type for array initializer");
 
       unsigned Bits =
-          std::max(CAT->getSize().getBitWidth(), ArrayBound.getBitWidth());
+          std::max(CAT->getSizeBitWidth(), ArrayBound.getBitWidth());
       llvm::APInt InitBound = CAT->getSize().zext(Bits);
       llvm::APInt AllocBound = ArrayBound.zext(Bits);
       if (InitBound.ugt(AllocBound)) {
@@ -10410,7 +10410,7 @@ bool RecordExprEvaluator::VisitCXXParenListOrInitListExpr(
 
     if (Field->getType()->isIncompleteArrayType()) {
       if (auto *CAT = Info.Ctx.getAsConstantArrayType(Init->getType())) {
-        if (!CAT->getSize().isZero()) {
+        if (!CAT->isZeroSize()) {
           // Bail out for now. This might sort of "work", but the rest of the
           // code isn't really prepared to handle it.
           Info.FFDiag(Init, diag::note_constexpr_unsupported_flexible_array);
@@ -10554,7 +10554,7 @@ bool RecordExprEvaluator::VisitCXXStdInitializerListExpr(
     // End pointer.
     if (!HandleLValueArrayAdjustment(Info, E, Array,
                                      ArrayType->getElementType(),
-                                     ArrayType->getSize().getZExtValue()))
+                                     ArrayType->getZExtSize()))
       return false;
     Array.moveInto(Result.getStructField(1));
   } else if (Info.Ctx.hasSameType(Field->getType(), Info.Ctx.getSizeType()))
@@ -10996,8 +10996,7 @@ namespace {
         return Error(E);
       }
 
-      Result = APValue(APValue::UninitArray(), 0,
-                       CAT->getSize().getZExtValue());
+      Result = APValue(APValue::UninitArray(), 0, CAT->getZExtSize());
       if (!Result.hasArrayFiller())
         return true;
 
@@ -11122,7 +11121,7 @@ bool ArrayExprEvaluator::VisitCXXParenListOrInitListExpr(
     Filler = Result.getArrayFiller();
 
   unsigned NumEltsToInit = Args.size();
-  unsigned NumElts = CAT->getSize().getZExtValue();
+  unsigned NumElts = CAT->getZExtSize();
 
   // If the initializer might depend on the array index, run it for each
   // array element.
@@ -11180,7 +11179,7 @@ bool ArrayExprEvaluator::VisitArrayInitLoopExpr(const ArrayInitLoopExpr *E) {
 
   auto *CAT = cast<ConstantArrayType>(E->getType()->castAsArrayTypeUnsafe());
 
-  uint64_t Elements = CAT->getSize().getZExtValue();
+  uint64_t Elements = CAT->getZExtSize();
   Result = APValue(APValue::UninitArray(), Elements, Elements);
 
   LValue Subobject = This;
@@ -11225,7 +11224,7 @@ bool ArrayExprEvaluator::VisitCXXConstructExpr(const CXXConstructExpr *E,
   bool HadZeroInit = Value->hasValue();
 
   if (const ConstantArrayType *CAT = Info.Ctx.getAsConstantArrayType(Type)) {
-    unsigned FinalSize = CAT->getSize().getZExtValue();
+    unsigned FinalSize = CAT->getZExtSize();
 
     // Preserve the array filler if we had prior zero-initialization.
     APValue Filler =
@@ -11940,7 +11939,7 @@ static bool isDesignatorAtObjectEnd(const ASTContext &Ctx, const LValue &LVal) {
         return true;
       const auto *CAT = cast<ConstantArrayType>(Ctx.getAsArrayType(BaseType));
       uint64_t Index = Entry.getAsArrayIndex();
-      if (Index + 1 != CAT->getSize())
+      if (Index + 1 != CAT->getZExtSize())
         return false;
       BaseType = CAT->getElementType();
     } else if (BaseType->isAnyComplexType()) {
diff --git a/clang/lib/AST/Interp/ByteCodeExprGen.cpp b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
index af214d4a8577c..6b19d6a620f32 100644
--- a/clang/lib/AST/Interp/ByteCodeExprGen.cpp
+++ b/clang/lib/AST/Interp/ByteCodeExprGen.cpp
@@ -819,7 +819,7 @@ bool ByteCodeExprGen<Emitter>::VisitImplicitValueInitExpr(const ImplicitValueIni
     const ArrayType *AT = QT->getAsArrayTypeUnsafe();
     assert(AT);
     const auto *CAT = cast<ConstantArrayType>(AT);
-    size_t NumElems = CAT->getSize().getZExtValue();
+    size_t NumElems = CAT->getZExtSize();
     PrimType ElemT = classifyPrim(CAT->getElementType());
 
     for (size_t I = 0; I != NumElems; ++I) {
@@ -992,7 +992,7 @@ bool ByteCodeExprGen<Emitter>::VisitInitListExpr(const InitListExpr *E) {
     if (const Expr *Filler = E->getArrayFiller()) {
       const ConstantArrayType *CAT =
           Ctx.getASTContext().getAsConstantArrayType(E->getType());
-      uint64_t NumElems = CAT->getSize().getZExtValue();
+      uint64_t NumElems = CAT->getZExtSize();
 
       for (; ElementIndex != NumElems; ++ElementIndex) {
         if (!this->visitArrayElemInit(ElementIndex, Filler))
@@ -1318,7 +1318,7 @@ bool ByteCodeExprGen<Emitter>::VisitStringLiteral(const StringLiteral *E) {
 
   // If the initializer string is too long, a diagnostic has already been
   // emitted. Read only the array length from the string literal.
-  unsigned ArraySize = CAT->getSize().getZExtValue();
+  unsigned ArraySize = CAT->getZExtSize();
   unsigned N = std::min(ArraySize, E->getLength());
   size_t CharWidth = E->getCharByteWidth();
 
@@ -1919,7 +1919,7 @@ bool ByteCodeExprGen<Emitter>::VisitCXXConstructExpr(
     const ConstantArrayType *CAT =
         Ctx.getASTContext().getAsConstantArrayType(E->getType());
     assert(CAT);
-    size_t NumElems = CAT->getSize().getZExtValue();
+    size_t NumElems = CAT->getZExtSize();
     const Function *Func = getFunction(E->getConstructor());
     if (!Func || !Func->isConstexpr())
       return false;
diff --git a/clang/lib/AST/Interp/EvaluationResult.cpp b/clang/lib/AST/Interp/EvaluationResult.cpp
index 07b28d07326f9..d567b551f7f6f 100644
--- a/clang/lib/AST/Interp/EvaluationResult.cpp
+++ b/clang/lib/AST/Interp/EvaluationResult.cpp
@@ -66,7 +66,7 @@ static bool CheckArrayInitialized(InterpState &S, SourceLocation Loc,
                                   const Pointer &BasePtr,
                                   const ConstantArrayType *CAT) {
   bool Result = true;
-  size_t NumElems = CAT->getSize().getZExtValue();
+  size_t NumElems = CAT->getZExtSize();
   QualType ElemType = CAT->getElementType();
 
   if (ElemType->isRecordType()) {
diff --git a/clang/lib/AST/Interp/Program.cpp b/clang/lib/AST/Interp/Program.cpp
index da6f72c62115d..25e938e015032 100644
--- a/clang/lib/AST/Interp/Program.cpp
+++ b/clang/lib/AST/Interp/Program.cpp
@@ -355,7 +355,7 @@ Descriptor *Program::createDescriptor(const DeclTy &D, const Type *Ty,
     QualType ElemTy = ArrayType->getElementType();
     // Array of well-known bounds.
     if (auto CAT = dyn_cast<ConstantArrayType>(ArrayType)) {
-      size_t NumElems = CAT->getSize().getZExtValue();
+      size_t NumElems = CAT->getZExtSize();
       if (std::optional<PrimType> T = Ctx.classify(ElemTy)) {
         // Arrays of primitives.
         unsigned ElemSize = primSize(*T);
diff --git a/clang/lib/AST/JSONNodeDumper.cpp b/clang/lib/AST/JSONNodeDumper.cpp
index e27d44fc2ffe6..5861d5a7ea0dd 100644
--- a/clang/lib/AST/JSONNodeDumper.cpp
+++ b/clang/lib/AST/JSONNodeDumper.cpp
@@ -695,7 +695,7 @@ void JSONNodeDumper::VisitArrayType(const ArrayType *AT) {
 void JSONNodeDumper::VisitConstantArrayType(const ConstantArrayType *CAT) {
   // FIXME: this should use ZExt instead of SExt, but JSON doesn't allow a
   // narrowing conversion to int64_t so it cannot be expressed.
-  JOS.attribute("size", CAT->getSize().getSExtValue());
+  JOS.attribute("size", CAT->getSExtSize());
   VisitArrayType(CAT);
 }
 
diff --git a/clang/lib/AST/MicrosoftMangle.cpp b/clang/lib/AST/MicrosoftMangle.cpp
index aa26bb7ed46f4..12c44f8fa028e 100644
--- a/clang/lib/AST/MicrosoftMangle.cpp
+++ b/clang/lib/AST/MicrosoftMangle.cpp
@@ -4022,10 +4022,8 @@ void MicrosoftMangleContextImpl::mangleStringLiteral(const StringLiteral *SL,
   // char bar[42] = "foobar";
   // Where it is truncated or zero-padded to fit the array. This is the length
   // used for mangling, and any trailing null-bytes also need to be mangled.
-  unsigned StringLength = getASTContext()
-                              .getAsConstantArrayType(SL->getType())
-                              ->getSize()
-                              .getZExtValue();
+  unsigned StringLength =
+      getASTContext().getAsConstantArrayType(SL->getType())->getZExtSize();
   unsigned StringByteLength = StringLength * SL->getCharByteWidth();
 
   // <char-type>: The "kind" of string literal is encoded into the mangled name.
diff --git a/clang/lib/AST/ScanfFormatString.cpp b/clang/lib/AST/ScanfFormatString.cpp
index 64c430e623b57..7ee21c8c61954 100644
--- a/clang/lib/AST/ScanfFormatString.cpp
+++ b/clang/lib/AST/ScanfFormatString.cpp
@@ -448,9 +448,7 @@ bool ScanfSpecifier::fixType(QualType QT, QualType RawQT,
     if (const ConstantArrayType *CAT = Ctx.getAsConstantArrayType(RawQT)) {
       if (CAT->getSizeModifier() == ArraySizeModifier::Normal)
         FieldWidth = OptionalAmount(OptionalAmount::Constant,
-                                    CAT->getSize().getZExtValue() - 1,
-                                    "", 0, false);
-
+                                    CAT->getZExtSize() - 1, "", 0, false);
     }
     return true;
   }
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
index 22666184c56cc..9a00b9ab83b38 100644
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -159,6 +159,22 @@ ArrayType::ArrayType(TypeClass tc, QualType et, QualType can,
   ArrayTypeBits.SizeModifier = llvm::to_underlying(sm);
 }
 
+ConstantArrayType *
+ConstantArrayType::Create(const ASTContext &Ctx, QualType ET, QualType Can,
+                          const llvm::APInt &Sz, const Expr *SzExpr,
+                          ArraySizeModifier SzMod, unsigned Qual) {
+  bool NeedsExternalSize = SzExpr != nullptr || Sz.ugt(0x0FFFFFFFFFFFFFFF) ||
+                           Sz.getBitWidth() > 0xFF;
+  if (!NeedsExternalSize)
+    return new (Ctx, alignof(ConstantArrayType)) ConstantArrayType(
+        ET, Can, Sz.getBitWidth(), Sz.getZExtValue(), SzMod, Qual);
+
+  auto *SzPtr = new (Ctx, alignof(ConstantArrayType::ExternalSize))
+      ConstantArrayType::ExternalSize(Sz, SzExpr);
+  return new (Ctx, alignof(ConstantArrayType))
+      ConstantArrayType(ET, Can, SzPtr, SzMod, Qual);
+}
+
 unsigned ConstantArrayType::getNumAddressingBits(const ASTContext &Context,
                                                  QualType ElementType,
                                                const llvm::APInt &NumElements) {
@@ -213,11 +229,10 @@ unsigned ConstantArrayType::getMaxSizeBits(const ASTContext &Context) {
 
 void ConstantArrayType::Profile(llvm::FoldingSetNodeID &ID,
                                 const ASTContext &Context, QualType ET,
-                                const llvm::APInt &ArraySize,
-                                const Expr *SizeExpr, ArraySizeModifier SizeMod,
-                                unsigned TypeQuals) {
+                                uint64_t ArraySize, const Expr *SizeExpr,
+                                ArraySizeModifier SizeMod, unsigned TypeQuals) {
   ID.AddPointer(ET.getAsOpaquePtr());
-  ID.AddInteger(ArraySize.getZExtValue());
+  ID.AddInteger(ArraySize);
   ID.AddInteger(llvm::to_underlying(SizeMod));
   ID.AddInteger(TypeQuals);
   ID.AddBoolean(SizeExpr != nullptr);
@@ -432,12 +447,8 @@ QualType QualType::getSingleStepDesugaredTypeImpl(QualType type,
 // Check that no type class has a non-trival destructor. Types are
 // allocated with the BumpPtrAllocator from ASTContext and therefore
 // their destructor is not executed.
-//
-// FIXME: ConstantArrayType is not trivially destructible because of its
-// APInt member. It should be replaced in favor of ASTContext allocation.
 #define TYPE(CLASS, BASE)                                                      \
-  static_assert(std::is_trivially_destructible<CLASS##Type>::value ||          \
-                    std::is_same<CLASS##Type, ConstantArrayType>::value,       \
+  static_assert(std::is_trivially_destructible<CLASS##Type>::value,            \
                 #CLASS "Type should be trivially destructible!");
 #include "clang/AST/TypeNodes.inc"
 
diff --git a/clang/lib/AST/TypePrinter.cpp b/clang/lib/AST/TypePrinter.cpp
index 7dcc4348f8e03..458452f3e880e 100644
--- a/clang/lib/AST/TypePrinter.cpp
+++ b/clang/lib/AST/TypePrinter.cpp
@@ -537,7 +537,7 @@ void TypePrinter::printConstantArrayAfter(const ConstantArrayType *T,
   if (T->getSizeModifier() == ArraySizeModifier::Static)
     OS << "static ";
 
-  OS << T->getSize().getZExtValue() << ']';
+  OS << T->getZExtSize() << ']';
   printAfter(T->getElementType(), OS);
 }
 
diff --git a/clang/lib/Analysis/CFG.cpp b/clang/lib/Analysis/CFG.cpp
index de70cbbf6cdb3..64e6155de090c 100644
--- a/clang/lib/Analysis/CFG.cpp
+++ b/clang/lib/Analysis/CFG.cpp
@@ -2039,7 +2039,7 @@ void CFGBuilder::addImplicitDtorsForDestructor(const CXXDestructorDecl *DD) {
     QualType QT = FI->getType();
     // It may be a multidimensional array.
     while (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) {
-      if (AT->getSize() == 0)
+      if (AT->isZeroSize())
         break;
       QT = AT->getElementType();
     }
@@ -2133,7 +2133,7 @@ bool CFGBuilder::hasTrivialDestructor(const VarDecl *VD) const {
 
   // Check for constant size array. Set type to array element type.
   while (const ConstantArrayType *AT = Context->getAsConstantArrayType(QT)) {
-    if (AT->getSize() == 0)
+    if (AT->isZeroSize())
       return true;
     QT = AT->getElementType();
   }
diff --git a/clang/lib/Analysis/UnsafeBufferUsage.cpp b/clang/lib/Analysis/UnsafeBufferUsage.cpp
index e1ff0d92f6b2f..e03fe1b683004 100644
--- a/clang/lib/Analysis/UnsafeBufferUsage.cpp
+++ b/clang/lib/Analysis/UnsafeBufferUsage.cpp
@@ -403,10 +403,11 @@ AST_MATCHER(CXXConstructExpr, isSafeSpanTwoParamConstruct) {
   QualType Arg0Ty = Arg0->IgnoreImplicit()->getType();
 
   if (Arg0Ty->isConstantArrayType()) {
-    const APInt &ConstArrSize = cast<ConstantArrayType>(Arg0Ty)->getSize();
+    const APSInt ConstArrSize =
+        APSInt(cast<ConstantArrayType>(Arg0Ty)->getSize());
 
     // Check form 4:
-    return Arg1CV && APSInt::compareValues(APSInt(ConstArrSize), *Arg1CV) == 0;
+    return Arg1CV && APSInt::compareValues(ConstArrSize, *Arg1CV) == 0;
   }
   return false;
 }
@@ -429,14 +430,13 @@ AST_MATCHER(ArraySubscriptExpr, isSafeArraySubscript) {
       BaseDRE->getDecl()->getType());
   if (!CATy)
     return false;
-  const APInt ArrSize = CATy->getSize();
 
   if (const auto *IdxLit = dyn_cast<IntegerLiteral>(Node.getIdx())) {
     const APInt ArrIdx = IdxLit->getValue();
     // FIXME: ArrIdx.isNegative() we could immediately emit an error as that's a
     // bug
     if (ArrIdx.isNonNegative() &&
-        ArrIdx.getLimitedValue() < ArrSize.getLimitedValue())
+        ArrIdx.getLimitedValue() < CATy->getLimitedSize())
       return true;
   }
 
diff --git a/clang/lib/CodeGen/ABIInfo.cpp b/clang/lib/CodeGen/ABIInfo.cpp
index efcff958ce545..acaae9f8c3d84 100644
--- a/clang/lib/CodeGen/ABIInfo.cpp
+++ b/clang/lib/CodeGen/ABIInfo.cpp
@@ -61,7 +61,7 @@ bool ABIInfo::isZeroLengthBitfieldPermittedInHomogeneousAggregate() const {
 bool ABIInfo::isHomogeneousAggregate(QualType Ty, const Type *&Base,
                                      uint64_t &Members) const {
   if (const ConstantArrayType *AT = getContext().getAsConstantArrayType(Ty)) {
-    uint64_t NElements = AT->getSize().getZExtValue();
+    uint64_t NElements = AT->getZExtSize();
     if (NElements == 0)
       return false;
     if (!isHomogeneousAggregate(AT->getElementType(), Base, Members))
@@ -98,7 +98,7 @@ bool ABIInfo::isHomogeneousAggregate(QualType Ty, const Type *&Base,
       QualType FT = FD->getType();
       while (const ConstantArrayType *AT =
              getContext().getAsConstantArrayType(FT)) {
-        if (AT->getSize().getZExtValue() == 0)
+        if (AT->isZeroSize())
           return false;
         FT = AT->getElementType();
       }
diff --git a/clang/lib/CodeGen/ABIInfoImpl.cpp b/clang/lib/CodeGen/ABIInfoImpl.cpp
index 2b20d5a13346d..dd59101ecc81b 100644
--- a/clang/lib/CodeGen/ABIInfoImpl.cpp
+++ b/clang/lib/CodeGen/ABIInfoImpl.cpp
@@ -257,7 +257,7 @@ bool CodeGen::isEmptyField(ASTContext &Context, const FieldDecl *FD,
   bool WasArray = false;
   if (AllowArrays)
     while (const ConstantArrayType *AT = Context.getAsConstantArrayType(FT)) {
-      if (AT->getSize() == 0)
+      if (AT->isZeroSize())
         return true;
       FT = AT->getElementType();
       // The [[no_unique_address]] special case below does not apply to
@@ -352,7 +352,7 @@ const Type *CodeGen::isSingleElementStruct(QualType T, ASTContext &Context) {
 
     // Treat single element arrays as the element.
     while (const ConstantArrayType *AT = Context.getAsConstantArrayType(FT)) {
-      if (AT->getSize().getZExtValue() != 1)
+      if (AT->getZExtSize() != 1)
         break;
       FT = AT->getElementType();
     }
diff --git a/clang/lib/CodeGen/CGCall.cpp b/clang/lib/CodeGen/CGCall.cpp
index a28d7888715d8..475d96b0e87d7 100644
--- a/clang/lib/CodeGen/CGCall.cpp
+++ b/clang/lib/CodeGen/CGCall.cpp
@@ -933,8 +933,8 @@ struct NoExpansion : TypeExpansion {
 static std::unique_ptr<TypeExpansion>
 getTypeExpansion(QualType Ty, const ASTContext &Context) {
   if (const ConstantArrayType *AT = Context.getAsConstantArrayType(Ty)) {
-    return std::make_unique<ConstantArrayExpansion>(
-        AT->getElementType(), AT->getSize().getZExtValue());
+    return std::make_unique<ConstantArrayExpansion>(AT->getElementType(),
+                                                    AT->getZExtSize());
   }
   if (const RecordType *RT = Ty->getAs<RecordType>()) {
     SmallVector<const CXXBaseSpecifier *, 1> Bases;
@@ -3086,7 +3086,7 @@ void CodeGenFunction::EmitFunctionProlog(const CGFunctionInfo &FI,
               llvm::Align Alignment =
                   CGM.getNaturalTypeAlignment(ETy).getAsAlign();
               AI->addAttrs(llvm::AttrBuilder(getLLVMContext()).addAlignmentAttr(Alignment));
-              uint64_t ArrSize = ArrTy->getSize().getZExtValue();
+              uint64_t ArrSize = ArrTy->getZExtSize();
               if (!ETy->isIncompleteType() && ETy->isConstantSizeType() &&
                   ArrSize) {
                 llvm::AttrBuilder Attrs(getLLVMContext());
diff --git a/clang/lib/CodeGen/CGDebugInfo.cpp b/clang/lib/CodeGen/CGDebugInfo.cpp
index c2c01439f2dc9..7a64f793f4b07 100644
--- a/clang/lib/CodeGen/CGDebugInfo.cpp
+++ b/clang/lib/CodeGen/CGDebugInfo.cpp
@@ -3239,7 +3239,7 @@ llvm::DIType *CGDebugInfo::CreateType(const ArrayType *Ty, llvm::DIFile *Unit) {
     //   };
     int64_t Count = -1; // Count == -1 is an unbounded array.
     if (const auto *CAT = dyn_cast<ConstantArrayType>(Ty))
-      Count = CAT->getSize().getZExtValue();
+      Count = CAT->getZExtSize();
     else if (const auto *VAT = dyn_cast<VariableArrayType>(Ty)) {
       if (Expr *Size = VAT->getSizeExpr()) {
         Expr::EvalResult Result;
diff --git a/clang/lib/CodeGen/CGExprCXX.cpp b/clang/lib/CodeGen/CGExprCXX.cpp
index 2adbef6d55122..35da0f1a89bc3 100644
--- a/clang/lib/CodeGen/CGExprCXX.cpp
+++ b/clang/lib/CodeGen/CGExprCXX.cpp
@@ -1073,8 +1073,7 @@ void CodeGenFunction::EmitNewArrayInitializer(
       // Move past these elements.
       InitListElements =
           cast<ConstantArrayType>(Init->getType()->getAsArrayTypeUnsafe())
-              ->getSize()
-              .getZExtValue();
+              ->getZExtSize();
       CurPtr = Builder.CreateConstInBoundsGEP(
           CurPtr, InitListElements, "string.init.end");
 
@@ -1591,8 +1590,7 @@ llvm::Value *CodeGenFunction::EmitCXXNewExpr(const CXXNewExpr *E) {
         isa<StringLiteral>(IgnoreParen) || isa<ObjCEncodeExpr>(IgnoreParen)) {
       minElements =
           cast<ConstantArrayType>(Init->getType()->getAsArrayTypeUnsafe())
-              ->getSize()
-              .getZExtValue();
+              ->getZExtSize();
     } else if (ILE || CPLIE) {
       minElements = ILE ? ILE->getNumInits() : CPLIE->getInitExprs().size();
     }
diff --git a/clang/lib/CodeGen/CGExprConstant.cpp b/clang/lib/CodeGen/CGExprConstant.cpp
index 75286dceb13a7..67a3cdc770426 100644
--- a/clang/lib/CodeGen/CGExprConstant.cpp
+++ b/clang/lib/CodeGen/CGExprConstant.cpp
@@ -656,7 +656,7 @@ static bool EmitDesignatedInitUpdater(ConstantEmitter &Emitter,
   }
 
   unsigned NumElementsToUpdate =
-      FillC ? CAT->getSize().getZExtValue() : Updater->getNumInits();
+      FillC ? CAT->getZExtSize() : Updater->getNumInits();
   for (unsigned I = 0; I != NumElementsToUpdate; ++I, Offset += ElemSize) {
     Expr *Init = nullptr;
     if (I < Updater->getNumInits())
@@ -1249,7 +1249,7 @@ class ConstExprEmitter :
     auto *CAT = CGM.getContext().getAsConstantArrayType(ILE->getType());
     assert(CAT && "can't emit array init for non-constant-bound array");
     unsigned NumInitElements = ILE->getNumInits();
-    unsigned NumElements = CAT->getSize().getZExtValue();
+    unsigned NumElements = CAT->getZExtSize();
 
     // Initialising an array requires us to automatically
     // initialise any elements that have not been initialised explicitly
@@ -1374,7 +1374,7 @@ class ConstExprEmitter :
 
     // Resize the string to the right size, adding zeros at the end, or
     // truncating as needed.
-    Str.resize(CAT->getSize().getZExtValue(), '\0');
+    Str.resize(CAT->getZExtSize(), '\0');
     return llvm::ConstantDataArray::getString(VMContext, Str, false);
   }
 
@@ -2382,7 +2382,7 @@ llvm::Constant *CodeGenModule::EmitNullConstant(QualType T) {
 
     llvm::Constant *Element =
       ConstantEmitter::emitNullForMemory(*this, ElementTy);
-    unsigned NumElements = CAT->getSize().getZExtValue();
+    unsigned NumElements = CAT->getZExtSize();
     SmallVector<llvm::Constant *, 8> Array(NumElements, Element);
     return llvm::ConstantArray::get(ATy, Array);
   }
diff --git a/clang/lib/CodeGen/CGObjCMac.cpp b/clang/lib/CodeGen/CGObjCMac.cpp
index e815e097e1fb4..ed8d7b9a065d7 100644
--- a/clang/lib/CodeGen/CGObjCMac.cpp
+++ b/clang/lib/CodeGen/CGObjCMac.cpp
@@ -2501,12 +2501,12 @@ void CGObjCCommonMac::BuildRCRecordLayout(const llvm::StructLayout *RecLayout,
 
     if (const ArrayType *Array = CGM.getContext().getAsArrayType(FQT)) {
       auto *CArray = cast<ConstantArrayType>(Array);
-      uint64_t ElCount = CArray->getSize().getZExtValue();
+      uint64_t ElCount = CArray->getZExtSize();
       assert(CArray && "only array with known element size is supported");
       FQT = CArray->getElementType();
       while (const ArrayType *Array = CGM.getContext().getAsArrayType(FQT)) {
         auto *CArray = cast<ConstantArrayType>(Array);
-        ElCount *= CArray->getSize().getZExtValue();
+        ElCount *= CArray->getZExtSize();
         FQT = CArray->getElementType();
       }
       if (FQT->isRecordType() && ElCount) {
@@ -5326,7 +5326,7 @@ void IvarLayoutBuilder::visitField(const FieldDecl *field,
   }
   // Unlike incomplete arrays, constant arrays can be nested.
   while (auto arrayType = CGM.getContext().getAsConstantArrayType(fieldType)) {
-    numElts *= arrayType->getSize().getZExtValue();
+    numElts *= arrayType->getZExtSize();
     fieldType = arrayType->getElementType();
   }
 
diff --git a/clang/lib/CodeGen/CGOpenMPRuntime.cpp b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
index e8a68dbcc6870..00e395c2a207f 100644
--- a/clang/lib/CodeGen/CGOpenMPRuntime.cpp
+++ b/clang/lib/CodeGen/CGOpenMPRuntime.cpp
@@ -6796,7 +6796,7 @@ class MappableExprsHandler {
                              OASE->getBase()->IgnoreParenImpCasts())
                              .getCanonicalType();
       if (const auto *ATy = dyn_cast<ConstantArrayType>(BaseQTy.getTypePtr()))
-        return ATy->getSize().getSExtValue() != 1;
+        return ATy->getSExtSize() != 1;
       // If we don't have a constant dimension length, we have to consider
       // the current section as having any size, so it is not necessarily
       // unitary. If it happen to be unity size, that's user fault.
@@ -7546,8 +7546,8 @@ class MappableExprsHandler {
       // it.
       if (DimSizes.size() < Components.size() - 1) {
         if (CAT)
-          DimSizes.push_back(llvm::ConstantInt::get(
-              CGF.Int64Ty, CAT->getSize().getZExtValue()));
+          DimSizes.push_back(
+              llvm::ConstantInt::get(CGF.Int64Ty, CAT->getZExtSize()));
         else if (VAT)
           DimSizes.push_back(CGF.Builder.CreateIntCast(
               CGF.EmitScalarExpr(VAT->getSizeExpr()), CGF.Int64Ty,
diff --git a/clang/lib/CodeGen/CodeGenFunction.cpp b/clang/lib/CodeGen/CodeGenFunction.cpp
index 4a3ff49b0007a..32a235b3fd057 100644
--- a/clang/lib/CodeGen/CodeGenFunction.cpp
+++ b/clang/lib/CodeGen/CodeGenFunction.cpp
@@ -2187,8 +2187,8 @@ llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType,
     dyn_cast<llvm::ArrayType>(addr.getElementType());
   while (llvmArrayType) {
     assert(isa<ConstantArrayType>(arrayType));
-    assert(cast<ConstantArrayType>(arrayType)->getSize().getZExtValue()
-             == llvmArrayType->getNumElements());
+    assert(cast<ConstantArrayType>(arrayType)->getZExtSize() ==
+           llvmArrayType->getNumElements());
 
     gepIndices.push_back(zero);
     countFromCLAs *= llvmArrayType->getNumElements();
@@ -2206,8 +2206,7 @@ llvm::Value *CodeGenFunction::emitArrayLength(const ArrayType *origArrayType,
     // as some other type (probably a packed struct). Compute the array
     // size, and just emit the 'begin' expression as a bitcast.
     while (arrayType) {
-      countFromCLAs *=
-          cast<ConstantArrayType>(arrayType)->getSize().getZExtValue();
+      countFromCLAs *= cast<ConstantArrayType>(arrayType)->getZExtSize();
       eltType = arrayType->getElementType();
       arrayType = getContext().getAsArrayType(eltType);
     }
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
index 8ceecff28cbc6..d79156c12a29f 100644
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -6244,7 +6244,7 @@ CodeGenModule::GetConstantArrayFromStringLiteral(const StringLiteral *E) {
     // Resize the string to the right size, which is indicated by its type.
     const ConstantArrayType *CAT = Context.getAsConstantArrayType(E->getType());
     assert(CAT && "String literal not of constant array type!");
-    Str.resize(CAT->getSize().getZExtValue());
+    Str.resize(CAT->getZExtSize());
     return llvm::ConstantDataArray::getString(VMContext, Str, false);
   }
 
diff --git a/clang/lib/CodeGen/CodeGenTypes.cpp b/clang/lib/CodeGen/CodeGenTypes.cpp
index a6b51bfef8765..afadc29ab1b02 100644
--- a/clang/lib/CodeGen/CodeGenTypes.cpp
+++ b/clang/lib/CodeGen/CodeGenTypes.cpp
@@ -601,7 +601,7 @@ llvm::Type *CodeGenTypes::ConvertType(QualType T) {
       EltTy = llvm::Type::getInt8Ty(getLLVMContext());
     }
 
-    ResultType = llvm::ArrayType::get(EltTy, A->getSize().getZExtValue());
+    ResultType = llvm::ArrayType::get(EltTy, A->getZExtSize());
     break;
   }
   case Type::ExtVector:
diff --git a/clang/lib/CodeGen/SwiftCallingConv.cpp b/clang/lib/CodeGen/SwiftCallingConv.cpp
index 16fbf52a517db..ab2e2bd0b3064 100644
--- a/clang/lib/CodeGen/SwiftCallingConv.cpp
+++ b/clang/lib/CodeGen/SwiftCallingConv.cpp
@@ -78,7 +78,7 @@ void SwiftAggLowering::addTypedData(QualType type, CharUnits begin) {
 
     QualType eltType = arrayType->getElementType();
     auto eltSize = CGM.getContext().getTypeSizeInChars(eltType);
-    for (uint64_t i = 0, e = arrayType->getSize().getZExtValue(); i != e; ++i) {
+    for (uint64_t i = 0, e = arrayType->getZExtSize(); i != e; ++i) {
       addTypedData(eltType, begin + i * eltSize);
     }
 
diff --git a/clang/lib/CodeGen/Targets/ARM.cpp b/clang/lib/CodeGen/Targets/ARM.cpp
index 5d42e6286e525..885d9c77d0e76 100644
--- a/clang/lib/CodeGen/Targets/ARM.cpp
+++ b/clang/lib/CodeGen/Targets/ARM.cpp
@@ -671,7 +671,7 @@ bool ARMABIInfo::isIllegalVectorType(QualType Ty) const {
 /// Return true if a type contains any 16-bit floating point vectors
 bool ARMABIInfo::containsAnyFP16Vectors(QualType Ty) const {
   if (const ConstantArrayType *AT = getContext().getAsConstantArrayType(Ty)) {
-    uint64_t NElements = AT->getSize().getZExtValue();
+    uint64_t NElements = AT->getZExtSize();
     if (NElements == 0)
       return false;
     return containsAnyFP16Vectors(AT->getElementType());
diff --git a/clang/lib/CodeGen/Targets/LoongArch.cpp b/clang/lib/CodeGen/Targets/LoongArch.cpp
index 63b9a1fdb988c..3f01d9ad90f13 100644
--- a/clang/lib/CodeGen/Targets/LoongArch.cpp
+++ b/clang/lib/CodeGen/Targets/LoongArch.cpp
@@ -146,7 +146,7 @@ bool LoongArchABIInfo::detectFARsEligibleStructHelper(
   }
 
   if (const ConstantArrayType *ATy = getContext().getAsConstantArrayType(Ty)) {
-    uint64_t ArraySize = ATy->getSize().getZExtValue();
+    uint64_t ArraySize = ATy->getZExtSize();
     QualType EltTy = ATy->getElementType();
     // Non-zero-length arrays of empty records make the struct ineligible to be
     // passed via FARs in C++.
diff --git a/clang/lib/CodeGen/Targets/RISCV.cpp b/clang/lib/CodeGen/Targets/RISCV.cpp
index 9a79424c4612c..7b32c79723562 100644
--- a/clang/lib/CodeGen/Targets/RISCV.cpp
+++ b/clang/lib/CodeGen/Targets/RISCV.cpp
@@ -152,7 +152,7 @@ bool RISCVABIInfo::detectFPCCEligibleStructHelper(QualType Ty, CharUnits CurOff,
   }
 
   if (const ConstantArrayType *ATy = getContext().getAsConstantArrayType(Ty)) {
-    uint64_t ArraySize = ATy->getSize().getZExtValue();
+    uint64_t ArraySize = ATy->getZExtSize();
     QualType EltTy = ATy->getElementType();
     // Non-zero-length arrays of empty records make the struct ineligible for
     // the FP calling convention in C++.
diff --git a/clang/lib/CodeGen/Targets/X86.cpp b/clang/lib/CodeGen/Targets/X86.cpp
index 2291c991fb110..1679e7776ee20 100644
--- a/clang/lib/CodeGen/Targets/X86.cpp
+++ b/clang/lib/CodeGen/Targets/X86.cpp
@@ -1993,7 +1993,7 @@ void X86_64ABIInfo::classify(QualType Ty, uint64_t OffsetBase, Class &Lo,
     // this, but it isn't worth it and would be harder to verify.
     Current = NoClass;
     uint64_t EltSize = getContext().getTypeSize(AT->getElementType());
-    uint64_t ArraySize = AT->getSize().getZExtValue();
+    uint64_t ArraySize = AT->getZExtSize();
 
     // The only case a 256-bit wide vector could be used is when the array
     // contains a single 256-bit element. Since Lo and Hi logic isn't extended
@@ -2295,7 +2295,7 @@ static bool BitsContainNoUserData(QualType Ty, unsigned StartBit,
 
   if (const ConstantArrayType *AT = Context.getAsConstantArrayType(Ty)) {
     unsigned EltSize = (unsigned)Context.getTypeSize(AT->getElementType());
-    unsigned NumElts = (unsigned)AT->getSize().getZExtValue();
+    unsigned NumElts = (unsigned)AT->getZExtSize();
 
     // Check each element to see if the element overlaps with the queried range.
     for (unsigned i = 0; i != NumElts; ++i) {
diff --git a/clang/lib/Sema/SemaChecking.cpp b/clang/lib/Sema/SemaChecking.cpp
index a0b256ab5579e..5044f8f7736dc 100644
--- a/clang/lib/Sema/SemaChecking.cpp
+++ b/clang/lib/Sema/SemaChecking.cpp
@@ -1098,7 +1098,7 @@ static bool ProcessFormatStringLiteral(const Expr *FormatExpr,
     const ConstantArrayType *T =
         Context.getAsConstantArrayType(Format->getType());
     assert(T && "String literal not of constant array type!");
-    size_t TypeSize = T->getSize().getZExtValue();
+    size_t TypeSize = T->getZExtSize();
     // In case there's a null byte somewhere.
     StrLen = std::min(std::max(TypeSize, size_t(1)) - 1, FormatStrRef.find(0));
     return true;
@@ -12970,7 +12970,7 @@ static void CheckFormatString(
   const ConstantArrayType *T =
     S.Context.getAsConstantArrayType(FExpr->getType());
   assert(T && "String literal not of constant array type!");
-  size_t TypeSize = T->getSize().getZExtValue();
+  size_t TypeSize = T->getZExtSize();
   size_t StrLen = std::min(std::max(TypeSize, size_t(1)) - 1, StrRef.size());
   const unsigned numDataArgs = Args.size() - firstDataArg;
 
@@ -13030,7 +13030,7 @@ bool Sema::FormatStringHasSArg(const StringLiteral *FExpr) {
   // Account for cases where the string literal is truncated in a declaration.
   const ConstantArrayType *T = Context.getAsConstantArrayType(FExpr->getType());
   assert(T && "String literal not of constant array type!");
-  size_t TypeSize = T->getSize().getZExtValue();
+  size_t TypeSize = T->getZExtSize();
   size_t StrLen = std::min(std::max(TypeSize, size_t(1)) - 1, StrRef.size());
   return analyze_format_string::ParseFormatStringHasSArg(Str, Str + StrLen,
                                                          getLangOpts(),
@@ -13993,7 +13993,7 @@ static bool isConstantSizeArrayWithMoreThanOneElement(QualType Ty,
   // Only handle constant-sized or VLAs, but not flexible members.
   if (const ConstantArrayType *CAT = Context.getAsConstantArrayType(Ty)) {
     // Only issue the FIXIT for arrays of size > 1.
-    if (CAT->getSize().getSExtValue() <= 1)
+    if (CAT->getZExtSize() <= 1)
       return false;
   } else if (!Ty->isVariableArrayType()) {
     return false;
diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
index 5850cd0ab6b9a..13ca830789417 100644
--- a/clang/lib/Sema/SemaDecl.cpp
+++ b/clang/lib/Sema/SemaDecl.cpp
@@ -8843,7 +8843,7 @@ void Sema::CheckVariableDeclarationType(VarDecl *NewVD) {
       return;
     }
     const auto *ATy = dyn_cast<ConstantArrayType>(T.getTypePtr());
-    if (!ATy || ATy->getSize().getSExtValue() != 0) {
+    if (!ATy || ATy->getZExtSize() != 0) {
       Diag(NewVD->getLocation(),
            diag::err_typecheck_wasm_table_must_have_zero_length);
       NewVD->setInvalidDecl();
diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
index e258a4f7c8941..bef7e9636a68d 100644
--- a/clang/lib/Sema/SemaDeclCXX.cpp
+++ b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -5282,7 +5282,7 @@ static bool isIncompleteOrZeroLengthArrayType(ASTContext &Context, QualType T) {
     return true;
 
   while (const ConstantArrayType *ArrayT = Context.getAsConstantArrayType(T)) {
-    if (!ArrayT->getSize())
+    if (ArrayT->isZeroSize())
       return true;
 
     T = ArrayT->getElementType();
diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
index 8725b09f8546c..a5af65ff775a1 100644
--- a/clang/lib/Sema/SemaExpr.cpp
+++ b/clang/lib/Sema/SemaExpr.cpp
@@ -6833,9 +6833,8 @@ Sema::CheckStaticArrayArgument(SourceLocation CallLoc,
                                              ArgCAT->getElementType())) {
     if (ArgCAT->getSize().ult(CAT->getSize())) {
       Diag(CallLoc, diag::warn_static_array_too_small)
-          << ArgExpr->getSourceRange()
-          << (unsigned)ArgCAT->getSize().getZExtValue()
-          << (unsigned)CAT->getSize().getZExtValue() << 0;
+          << ArgExpr->getSourceRange() << (unsigned)ArgCAT->getZExtSize()
+          << (unsigned)CAT->getZExtSize() << 0;
       DiagnoseCalleeStaticArrayParam(*this, Param);
     }
     return;
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
index c34a40fa7c81a..51c8e04bee8c3 100644
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -6083,7 +6083,7 @@ static uint64_t EvaluateArrayTypeTrait(Sema &Self, ArrayTypeTrait ATT,
 
       if (Matched && T->isArrayType()) {
         if (const ConstantArrayType *CAT = Self.Context.getAsConstantArrayType(T))
-          return CAT->getSize().getLimitedValue();
+          return CAT->getLimitedSize();
       }
     }
     return 0;
diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
index aa470adb30b47..2b4805d62d07d 100644
--- a/clang/lib/Sema/SemaInit.cpp
+++ b/clang/lib/Sema/SemaInit.cpp
@@ -213,7 +213,7 @@ static void CheckStringInit(Expr *Str, QualType &DeclT, const ArrayType *AT,
   // Get the length of the string as parsed.
   auto *ConstantArrayTy =
       cast<ConstantArrayType>(Str->getType()->getAsArrayTypeUnsafe());
-  uint64_t StrLength = ConstantArrayTy->getSize().getZExtValue();
+  uint64_t StrLength = ConstantArrayTy->getZExtSize();
 
   if (CheckC23ConstexprInit)
     if (const StringLiteral *SL = dyn_cast<StringLiteral>(Str->IgnoreParens()))
@@ -246,14 +246,13 @@ static void CheckStringInit(Expr *Str, QualType &DeclT, const ArrayType *AT,
     }
 
     // [dcl.init.string]p2
-    if (StrLength > CAT->getSize().getZExtValue())
+    if (StrLength > CAT->getZExtSize())
       S.Diag(Str->getBeginLoc(),
              diag::err_initializer_string_for_char_array_too_long)
-          << CAT->getSize().getZExtValue() << StrLength
-          << Str->getSourceRange();
+          << CAT->getZExtSize() << StrLength << Str->getSourceRange();
   } else {
     // C99 6.7.8p14.
-    if (StrLength-1 > CAT->getSize().getZExtValue())
+    if (StrLength - 1 > CAT->getZExtSize())
       S.Diag(Str->getBeginLoc(),
              diag::ext_initializer_string_for_char_array_too_long)
           << Str->getSourceRange();
@@ -879,7 +878,7 @@ InitListChecker::FillInEmptyInitializations(const InitializedEntity &Entity,
   if (const ArrayType *AType = SemaRef.Context.getAsArrayType(ILE->getType())) {
     ElementType = AType->getElementType();
     if (const auto *CAType = dyn_cast<ConstantArrayType>(AType))
-      NumElements = CAType->getSize().getZExtValue();
+      NumElements = CAType->getZExtSize();
     // For an array new with an unknown bound, ask for one additional element
     // in order to populate the array filler.
     if (Entity.isVariableLengthArrayNew())
@@ -1016,7 +1015,7 @@ int InitListChecker::numArrayElements(QualType DeclType) {
   int maxElements = 0x7FFFFFFF;
   if (const ConstantArrayType *CAT =
         SemaRef.Context.getAsConstantArrayType(DeclType)) {
-    maxElements = static_cast<int>(CAT->getSize().getZExtValue());
+    maxElements = static_cast<int>(CAT->getZExtSize());
   }
   return maxElements;
 }
@@ -3101,7 +3100,7 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
       // Get the length of the string.
       uint64_t StrLen = SL->getLength();
       if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
-        StrLen = cast<ConstantArrayType>(AT)->getSize().getZExtValue();
+        StrLen = cast<ConstantArrayType>(AT)->getZExtSize();
       StructuredList->resizeInits(Context, StrLen);
 
       // Build a literal for each character in the string, and put them into
@@ -3124,7 +3123,7 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
       // Get the length of the string.
       uint64_t StrLen = Str.size();
       if (cast<ConstantArrayType>(AT)->getSize().ult(StrLen))
-        StrLen = cast<ConstantArrayType>(AT)->getSize().getZExtValue();
+        StrLen = cast<ConstantArrayType>(AT)->getZExtSize();
       StructuredList->resizeInits(Context, StrLen);
 
       // Build a literal for each character in the string, and put them into
@@ -3283,7 +3282,7 @@ InitListChecker::createInitListExpr(QualType CurrentObjectType,
   if (const ArrayType *AType
       = SemaRef.Context.getAsArrayType(CurrentObjectType)) {
     if (const ConstantArrayType *CAType = dyn_cast<ConstantArrayType>(AType)) {
-      NumElements = CAType->getSize().getZExtValue();
+      NumElements = CAType->getZExtSize();
       // Simple heuristic so that we don't allocate a very large
       // initializer with many empty entries at the end.
       if (NumElements > ExpectedNumInits)
@@ -5492,7 +5491,7 @@ static void TryOrBuildParenListInitialization(
     //   having k elements.
     if (const ConstantArrayType *CAT =
             S.getASTContext().getAsConstantArrayType(Entity.getType())) {
-      ArrayLength = CAT->getSize().getZExtValue();
+      ArrayLength = CAT->getZExtSize();
       ResultType = Entity.getType();
     } else if (const VariableArrayType *VAT =
                    S.getASTContext().getAsVariableArrayType(Entity.getType())) {
diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
index e9ad7bbde0f9b..0ba54a3a9cae3 100644
--- a/clang/lib/Sema/SemaOpenMP.cpp
+++ b/clang/lib/Sema/SemaOpenMP.cpp
@@ -21284,7 +21284,7 @@ static bool checkArrayExpressionDoesNotReferToWholeSize(Sema &SemaRef,
   if (isa<ArraySubscriptExpr>(E) ||
       (OASE && OASE->getColonLocFirst().isInvalid())) {
     if (const auto *ATy = dyn_cast<ConstantArrayType>(BaseQTy.getTypePtr()))
-      return ATy->getSize().getSExtValue() != 1;
+      return ATy->getSExtSize() != 1;
     // Size can't be evaluated statically.
     return false;
   }
@@ -21325,7 +21325,7 @@ static bool checkArrayExpressionDoesNotReferToWholeSize(Sema &SemaRef,
     return false; // Can't get the integer value as a constant.
 
   llvm::APSInt ConstLength = Result.Val.getInt();
-  return CATy->getSize().getSExtValue() != ConstLength.getSExtValue();
+  return CATy->getSExtSize() != ConstLength.getSExtValue();
 }
 
 // Return true if it can be proven that the provided array expression (array
@@ -21350,7 +21350,7 @@ static bool checkArrayExpressionDoesNotReferToUnitySize(Sema &SemaRef,
   // is pointer.
   if (!Length) {
     if (const auto *ATy = dyn_cast<ConstantArrayType>(BaseQTy.getTypePtr()))
-      return ATy->getSize().getSExtValue() != 1;
+      return ATy->getSExtSize() != 1;
     // We cannot assume anything.
     return false;
   }
diff --git a/clang/lib/Sema/SemaSYCL.cpp b/clang/lib/Sema/SemaSYCL.cpp
index ca0254d29e7f4..18ebaa13346a4 100644
--- a/clang/lib/Sema/SemaSYCL.cpp
+++ b/clang/lib/Sema/SemaSYCL.cpp
@@ -35,7 +35,7 @@ Sema::SemaDiagnosticBuilder Sema::SYCLDiagIfDeviceCode(SourceLocation Loc,
 
 static bool isZeroSizedArray(Sema &SemaRef, QualType Ty) {
   if (const auto *CAT = SemaRef.getASTContext().getAsConstantArrayType(Ty))
-    return CAT->getSize() == 0;
+    return CAT->isZeroSize();
   return false;
 }
 
diff --git a/clang/lib/StaticAnalyzer/Checkers/CastSizeChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/CastSizeChecker.cpp
index a50772f881f7d..2cff97a591b8c 100644
--- a/clang/lib/StaticAnalyzer/Checkers/CastSizeChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/CastSizeChecker.cpp
@@ -68,7 +68,7 @@ static bool evenFlexibleArraySize(ASTContext &Ctx, CharUnits RegionSize,
     FlexSize = Ctx.getTypeSizeInChars(ElemType);
     if (ArrayTy->getSize() == 1 && TypeSize > FlexSize)
       TypeSize -= FlexSize;
-    else if (ArrayTy->getSize() != 0)
+    else if (!ArrayTy->isZeroSize())
       return false;
   } else if (RD->hasFlexibleArrayMember()) {
     FlexSize = Ctx.getTypeSizeInChars(ElemType);
diff --git a/clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp b/clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp
index eee9449f31805..4f35d9442ad98 100644
--- a/clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp
+++ b/clang/lib/StaticAnalyzer/Checkers/PaddingChecker.cpp
@@ -117,7 +117,7 @@ class PaddingChecker : public Checker<check::ASTDecl<TranslationUnitDecl>> {
       return;
     uint64_t Elts = 0;
     if (const ConstantArrayType *CArrTy = dyn_cast<ConstantArrayType>(ArrTy))
-      Elts = CArrTy->getSize().getZExtValue();
+      Elts = CArrTy->getZExtSize();
     if (Elts == 0)
       return;
     const RecordType *RT = ArrTy->getElementType()->getAs<RecordType>();
diff --git a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
index 16db6b249dc92..a98e32ec4c6f0 100644
--- a/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
+++ b/clang/lib/StaticAnalyzer/Core/MemRegion.cpp
@@ -817,7 +817,7 @@ DefinedOrUnknownSVal MemRegionManager::getStaticSize(const MemRegion *MR,
       };
       auto IsArrayOfZero = [](const ArrayType *AT) {
         const auto *CAT = dyn_cast<ConstantArrayType>(AT);
-        return CAT && CAT->getSize() == 0;
+        return CAT && CAT->isZeroSize();
       };
       auto IsArrayOfOne = [](const ArrayType *AT) {
         const auto *CAT = dyn_cast<ConstantArrayType>(AT);
diff --git a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
index da9a1a1a4d1f6..755a8c4b22fd9 100644
--- a/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
+++ b/clang/lib/StaticAnalyzer/Core/RegionStore.cpp
@@ -1166,7 +1166,7 @@ void InvalidateRegionsWorker::VisitCluster(const MemRegion *baseR,
 
       // Compute lower and upper offsets for region within array.
       if (const ConstantArrayType *CAT = dyn_cast<ConstantArrayType>(AT))
-        NumElements = CAT->getSize().getZExtValue();
+        NumElements = CAT->getZExtSize();
       if (!NumElements) // We are not dealing with a constant size array
         goto conjure_default;
       QualType ElementTy = AT->getElementType();
@@ -1613,7 +1613,7 @@ getConstantArrayExtents(const ConstantArrayType *CAT) {
   CAT = cast<ConstantArrayType>(CAT->getCanonicalTypeInternal());
   SmallVector<uint64_t, 2> Extents;
   do {
-    Extents.push_back(CAT->getSize().getZExtValue());
+    Extents.push_back(CAT->getZExtSize());
   } while ((CAT = dyn_cast<ConstantArrayType>(CAT->getElementType())));
   return Extents;
 }
@@ -2436,7 +2436,7 @@ std::optional<RegionBindingsRef> RegionStoreManager::tryBindSmallArray(
     return std::nullopt;
 
   // If the array is too big, create a LCV instead.
-  uint64_t ArrSize = CAT->getSize().getLimitedValue();
+  uint64_t ArrSize = CAT->getLimitedSize();
   if (ArrSize > SmallArrayLimit)
     return std::nullopt;
 
@@ -2465,7 +2465,7 @@ RegionStoreManager::bindArray(RegionBindingsConstRef B,
   std::optional<uint64_t> Size;
 
   if (const ConstantArrayType* CAT = dyn_cast<ConstantArrayType>(AT))
-    Size = CAT->getSize().getZExtValue();
+    Size = CAT->getZExtSize();
 
   // Check if the init expr is a literal. If so, bind the rvalue instead.
   // FIXME: It's not responsibility of the Store to transform this lvalue