Index: include/llvm/CodeGen/DebugHandlerBase.h
===================================================================
--- include/llvm/CodeGen/DebugHandlerBase.h
+++ include/llvm/CodeGen/DebugHandlerBase.h
@@ -129,7 +129,7 @@
   const MCExpr *getFunctionLocalOffsetAfterInsn(const MachineInstr *MI);
 
   /// If this type is derived from a base type then return base type size.
-  static uint64_t getBaseTypeSize(const DITypeRef TyRef);
+  static uint64_t getBaseTypeSize(const DIType *Ty);
 };
 
 }
Index: include/llvm/IR/DebugInfoMetadata.h
===================================================================
--- include/llvm/IR/DebugInfoMetadata.h
+++ include/llvm/IR/DebugInfoMetadata.h
@@ -60,44 +60,6 @@
 
 namespace llvm {
 
-/// Holds a subclass of DINode.
-///
-/// FIXME: This class doesn't currently make much sense.  Previously it was a
-/// union beteen MDString (for ODR-uniqued types) and things like DIType.  To
-/// support CodeView work, it wasn't deleted outright when MDString-based type
-/// references were deleted; we'll soon need a similar concept for CodeView
-/// DITypeIndex.
-template <class T> class TypedDINodeRef {
-  const Metadata *MD = nullptr;
-
-public:
-  TypedDINodeRef() = default;
-  TypedDINodeRef(std::nullptr_t) {}
-  TypedDINodeRef(const T *MD) : MD(MD) {}
-
-  explicit TypedDINodeRef(const Metadata *MD) : MD(MD) {
-    assert((!MD || isa<T>(MD)) && "Expected valid type ref");
-  }
-
-  template <class U>
-  TypedDINodeRef(
-      const TypedDINodeRef<U> &X,
-      typename std::enable_if<std::is_convertible<U *, T *>::value>::type * =
-          nullptr)
-      : MD(X) {}
-
-  operator Metadata *() const { return const_cast<Metadata *>(MD); }
-
-  T *resolve() const { return const_cast<T *>(cast_or_null<T>(MD)); }
-
-  bool operator==(const TypedDINodeRef<T> &X) const { return MD == X.MD; }
-  bool operator!=(const TypedDINodeRef<T> &X) const { return MD != X.MD; }
-};
-
-using DINodeRef = TypedDINodeRef<DINode>;
-using DIScopeRef = TypedDINodeRef<DIScope>;
-using DITypeRef = TypedDINodeRef<DIType>;
-
 class DITypeRefArray {
   const MDTuple *N = nullptr;
 
@@ -114,17 +76,19 @@
 
   // FIXME: Fix callers and remove condition on N.
   unsigned size() const { return N ? N->getNumOperands() : 0u; }
-  DITypeRef operator[](unsigned I) const { return DITypeRef(N->getOperand(I)); }
+  DIType *operator[](unsigned I) const {
+    return cast_or_null<DIType>(N->getOperand(I));
+  }
 
-  class iterator : std::iterator<std::input_iterator_tag, DITypeRef,
-                                 std::ptrdiff_t, void, DITypeRef> {
+  class iterator : std::iterator<std::input_iterator_tag, DIType *,
+                                 std::ptrdiff_t, void, DIType *> {
     MDNode::op_iterator I = nullptr;
 
   public:
     iterator() = default;
     explicit iterator(MDNode::op_iterator I) : I(I) {}
 
-    DITypeRef operator*() const { return DITypeRef(*I); }
+    DIType *operator*() const { return cast_or_null<DIType>(*I); }
 
     iterator &operator++() {
       ++I;
@@ -241,18 +205,6 @@
   }
 };
 
-template <class T> struct simplify_type<const TypedDINodeRef<T>> {
-  using SimpleType = Metadata *;
-
-  static SimpleType getSimplifiedValue(const TypedDINodeRef<T> &MD) {
-    return MD;
-  }
-};
-
-template <class T>
-struct simplify_type<TypedDINodeRef<T>>
-    : simplify_type<const TypedDINodeRef<T>> {};
-
 /// Generic tagged DWARF-like metadata node.
 ///
 /// An un-specialized DWARF-like metadata node.  The first operand is a
@@ -459,7 +411,7 @@
   inline Optional<StringRef> getSource() const;
 
   StringRef getName() const;
-  DIScopeRef getScope() const;
+  DIScope *getScope() const;
 
   /// Return the raw underlying file.
   ///
@@ -673,7 +625,7 @@
   uint64_t getOffsetInBits() const { return OffsetInBits; }
   DIFlags getFlags() const { return Flags; }
 
-  DIScopeRef getScope() const { return DIScopeRef(getRawScope()); }
+  DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
   StringRef getName() const { return getStringOperand(2); }
 
 
@@ -818,14 +770,12 @@
         DWARFAddressSpace(DWARFAddressSpace) {}
   ~DIDerivedType() = default;
 
-  static DIDerivedType *getImpl(LLVMContext &Context, unsigned Tag,
-                                StringRef Name, DIFile *File, unsigned Line,
-                                DIScopeRef Scope, DITypeRef BaseType,
-                                uint64_t SizeInBits, uint32_t AlignInBits,
-                                uint64_t OffsetInBits,
-                                Optional<unsigned> DWARFAddressSpace,
-                                DIFlags Flags, Metadata *ExtraData,
-                                StorageType Storage, bool ShouldCreate = true) {
+  static DIDerivedType *
+  getImpl(LLVMContext &Context, unsigned Tag, StringRef Name, DIFile *File,
+          unsigned Line, DIScope *Scope, DIType *BaseType, uint64_t SizeInBits,
+          uint32_t AlignInBits, uint64_t OffsetInBits,
+          Optional<unsigned> DWARFAddressSpace, DIFlags Flags,
+          Metadata *ExtraData, StorageType Storage, bool ShouldCreate = true) {
     return getImpl(Context, Tag, getCanonicalMDString(Context, Name), File,
                    Line, Scope, BaseType, SizeInBits, AlignInBits, OffsetInBits,
                    DWARFAddressSpace, Flags, ExtraData, Storage, ShouldCreate);
@@ -859,7 +809,7 @@
                      ExtraData))
   DEFINE_MDNODE_GET(DIDerivedType,
                     (unsigned Tag, StringRef Name, DIFile *File, unsigned Line,
-                     DIScopeRef Scope, DITypeRef BaseType, uint64_t SizeInBits,
+                     DIScope *Scope, DIType *BaseType, uint64_t SizeInBits,
                      uint32_t AlignInBits, uint64_t OffsetInBits,
                      Optional<unsigned> DWARFAddressSpace, DIFlags Flags,
                      Metadata *ExtraData = nullptr),
@@ -870,7 +820,7 @@
   TempDIDerivedType clone() const { return cloneImpl(); }
 
   /// Get the base type this is derived from.
-  DITypeRef getBaseType() const { return DITypeRef(getRawBaseType()); }
+  DIType *getBaseType() const { return cast_or_null<DIType>(getRawBaseType()); }
   Metadata *getRawBaseType() const { return getOperand(3); }
 
   /// \returns The DWARF address space of the memory pointed to or referenced by
@@ -890,9 +840,9 @@
 
   /// Get casted version of extra data.
   /// @{
-  DITypeRef getClassType() const {
+  DIType *getClassType() const {
     assert(getTag() == dwarf::DW_TAG_ptr_to_member_type);
-    return DITypeRef(getExtraData());
+    return cast_or_null<DIType>(getExtraData());
   }
 
   DIObjCProperty *getObjCProperty() const {
@@ -964,12 +914,12 @@
 
   static DICompositeType *
   getImpl(LLVMContext &Context, unsigned Tag, StringRef Name, Metadata *File,
-          unsigned Line, DIScopeRef Scope, DITypeRef BaseType,
-          uint64_t SizeInBits, uint32_t AlignInBits, uint64_t OffsetInBits,
-          DIFlags Flags, DINodeArray Elements, unsigned RuntimeLang,
-          DITypeRef VTableHolder, DITemplateParameterArray TemplateParams,
-          StringRef Identifier, DIDerivedType *Discriminator,
-          StorageType Storage, bool ShouldCreate = true) {
+          unsigned Line, DIScope *Scope, DIType *BaseType, uint64_t SizeInBits,
+          uint32_t AlignInBits, uint64_t OffsetInBits, DIFlags Flags,
+          DINodeArray Elements, unsigned RuntimeLang, DIType *VTableHolder,
+          DITemplateParameterArray TemplateParams, StringRef Identifier,
+          DIDerivedType *Discriminator, StorageType Storage,
+          bool ShouldCreate = true) {
     return getImpl(
         Context, Tag, getCanonicalMDString(Context, Name), File, Line, Scope,
         BaseType, SizeInBits, AlignInBits, OffsetInBits, Flags, Elements.get(),
@@ -996,12 +946,13 @@
 public:
   DEFINE_MDNODE_GET(DICompositeType,
                     (unsigned Tag, StringRef Name, DIFile *File, unsigned Line,
-                     DIScopeRef Scope, DITypeRef BaseType, uint64_t SizeInBits,
-                     uint32_t AlignInBits, uint64_t OffsetInBits,
-                     DIFlags Flags, DINodeArray Elements, unsigned RuntimeLang,
-                     DITypeRef VTableHolder,
+                     DIScope *Scope, DIType *BaseType, uint64_t SizeInBits,
+                     uint32_t AlignInBits, uint64_t OffsetInBits, DIFlags Flags,
+                     DINodeArray Elements, unsigned RuntimeLang,
+                     DIType *VTableHolder,
                      DITemplateParameterArray TemplateParams = nullptr,
-                     StringRef Identifier = "", DIDerivedType *Discriminator = nullptr),
+                     StringRef Identifier = "",
+                     DIDerivedType *Discriminator = nullptr),
                     (Tag, Name, File, Line, Scope, BaseType, SizeInBits,
                      AlignInBits, OffsetInBits, Flags, Elements, RuntimeLang,
                      VTableHolder, TemplateParams, Identifier, Discriminator))
@@ -1054,11 +1005,13 @@
                unsigned RuntimeLang, Metadata *VTableHolder,
                Metadata *TemplateParams, Metadata *Discriminator);
 
-  DITypeRef getBaseType() const { return DITypeRef(getRawBaseType()); }
+  DIType *getBaseType() const { return cast_or_null<DIType>(getRawBaseType()); }
   DINodeArray getElements() const {
     return cast_or_null<MDTuple>(getRawElements());
   }
-  DITypeRef getVTableHolder() const { return DITypeRef(getRawVTableHolder()); }
+  DIType *getVTableHolder() const {
+    return cast_or_null<DIType>(getRawVTableHolder());
+  }
   DITemplateParameterArray getTemplateParams() const {
     return cast_or_null<MDTuple>(getRawTemplateParams());
   }
@@ -1088,7 +1041,7 @@
     replaceOperandWith(4, Elements.get());
   }
 
-  void replaceVTableHolder(DITypeRef VTableHolder) {
+  void replaceVTableHolder(DIType *VTableHolder) {
     replaceOperandWith(5, VTableHolder);
   }
 
@@ -1705,9 +1658,9 @@
   ~DISubprogram() = default;
 
   static DISubprogram *
-  getImpl(LLVMContext &Context, DIScopeRef Scope, StringRef Name,
+  getImpl(LLVMContext &Context, DIScope *Scope, StringRef Name,
           StringRef LinkageName, DIFile *File, unsigned Line,
-          DISubroutineType *Type, unsigned ScopeLine, DITypeRef ContainingType,
+          DISubroutineType *Type, unsigned ScopeLine, DIType *ContainingType,
           unsigned VirtualIndex, int ThisAdjustment, DIFlags Flags,
           DISPFlags SPFlags, DICompileUnit *Unit,
           DITemplateParameterArray TemplateParams, DISubprogram *Declaration,
@@ -1742,9 +1695,9 @@
 public:
   DEFINE_MDNODE_GET(
       DISubprogram,
-      (DIScopeRef Scope, StringRef Name, StringRef LinkageName, DIFile *File,
+      (DIScope * Scope, StringRef Name, StringRef LinkageName, DIFile *File,
        unsigned Line, DISubroutineType *Type, unsigned ScopeLine,
-       DITypeRef ContainingType, unsigned VirtualIndex, int ThisAdjustment,
+       DIType *ContainingType, unsigned VirtualIndex, int ThisAdjustment,
        DIFlags Flags, DISPFlags SPFlags, DICompileUnit *Unit,
        DITemplateParameterArray TemplateParams = nullptr,
        DISubprogram *Declaration = nullptr, DINodeArray RetainedNodes = nullptr,
@@ -1828,7 +1781,7 @@
   // Returns true if this subprogram is a thunk generated by the compiler.
   bool isThunk() const { return getFlags() & FlagThunk; }
 
-  DIScopeRef getScope() const { return DIScopeRef(getRawScope()); }
+  DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
 
   StringRef getName() const { return getStringOperand(2); }
   StringRef getLinkageName() const { return getStringOperand(3); }
@@ -1836,8 +1789,8 @@
   DISubroutineType *getType() const {
     return cast_or_null<DISubroutineType>(getRawType());
   }
-  DITypeRef getContainingType() const {
-    return DITypeRef(getRawContainingType());
+  DIType *getContainingType() const {
+    return cast_or_null<DIType>(getRawContainingType());
   }
 
   DICompileUnit *getUnit() const {
@@ -2182,7 +2135,7 @@
 
 public:
   StringRef getName() const { return getStringOperand(0); }
-  DITypeRef getType() const { return DITypeRef(getRawType()); }
+  DIType *getType() const { return cast_or_null<DIType>(getRawType()); }
 
   MDString *getRawName() const { return getOperandAs<MDString>(0); }
   Metadata *getRawType() const { return getOperand(1); }
@@ -2204,7 +2157,7 @@
   ~DITemplateTypeParameter() = default;
 
   static DITemplateTypeParameter *getImpl(LLVMContext &Context, StringRef Name,
-                                          DITypeRef Type, StorageType Storage,
+                                          DIType *Type, StorageType Storage,
                                           bool ShouldCreate = true) {
     return getImpl(Context, getCanonicalMDString(Context, Name), Type, Storage,
                    ShouldCreate);
@@ -2218,7 +2171,7 @@
   }
 
 public:
-  DEFINE_MDNODE_GET(DITemplateTypeParameter, (StringRef Name, DITypeRef Type),
+  DEFINE_MDNODE_GET(DITemplateTypeParameter, (StringRef Name, DIType *Type),
                     (Name, Type))
   DEFINE_MDNODE_GET(DITemplateTypeParameter, (MDString * Name, Metadata *Type),
                     (Name, Type))
@@ -2241,7 +2194,7 @@
   ~DITemplateValueParameter() = default;
 
   static DITemplateValueParameter *getImpl(LLVMContext &Context, unsigned Tag,
-                                           StringRef Name, DITypeRef Type,
+                                           StringRef Name, DIType *Type,
                                            Metadata *Value, StorageType Storage,
                                            bool ShouldCreate = true) {
     return getImpl(Context, Tag, getCanonicalMDString(Context, Name), Type,
@@ -2258,8 +2211,9 @@
   }
 
 public:
-  DEFINE_MDNODE_GET(DITemplateValueParameter, (unsigned Tag, StringRef Name,
-                                               DITypeRef Type, Metadata *Value),
+  DEFINE_MDNODE_GET(DITemplateValueParameter,
+                    (unsigned Tag, StringRef Name, DIType *Type,
+                     Metadata *Value),
                     (Tag, Name, Type, Value))
   DEFINE_MDNODE_GET(DITemplateValueParameter, (unsigned Tag, MDString *Name,
                                                Metadata *Type, Metadata *Value),
@@ -2291,7 +2245,7 @@
   DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
   StringRef getName() const { return getStringOperand(1); }
   DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
-  DITypeRef getType() const { return DITypeRef(getRawType()); }
+  DIType *getType() const { return cast_or_null<DIType>(getRawType()); }
   uint32_t getAlignInBits() const { return AlignInBits; }
   uint32_t getAlignInBytes() const { return getAlignInBits() / CHAR_BIT; }
   /// Determines the size of the variable's type.
@@ -2300,7 +2254,7 @@
   /// Return the signedness of this variable's type, or None if this type is
   /// neither signed nor unsigned.
   Optional<DIBasicType::Signedness> getSignedness() const {
-    if (auto *BT = dyn_cast<DIBasicType>(getType().resolve()))
+    if (auto *BT = dyn_cast<DIBasicType>(getType()))
       return BT->getSignedness();
     return None;
   }
@@ -2611,7 +2565,7 @@
 
   static DIGlobalVariable *
   getImpl(LLVMContext &Context, DIScope *Scope, StringRef Name,
-          StringRef LinkageName, DIFile *File, unsigned Line, DITypeRef Type,
+          StringRef LinkageName, DIFile *File, unsigned Line, DIType *Type,
           bool IsLocalToUnit, bool IsDefinition,
           DIDerivedType *StaticDataMemberDeclaration, MDTuple *TemplateParams,
           uint32_t AlignInBits, StorageType Storage, bool ShouldCreate = true) {
@@ -2638,7 +2592,7 @@
 public:
   DEFINE_MDNODE_GET(DIGlobalVariable,
                     (DIScope * Scope, StringRef Name, StringRef LinkageName,
-                     DIFile *File, unsigned Line, DITypeRef Type,
+                     DIFile *File, unsigned Line, DIType *Type,
                      bool IsLocalToUnit, bool IsDefinition,
                      DIDerivedType *StaticDataMemberDeclaration,
                      MDTuple *TemplateParams, uint32_t AlignInBits),
@@ -2755,7 +2709,7 @@
 
   static DILocalVariable *getImpl(LLVMContext &Context, DIScope *Scope,
                                   StringRef Name, DIFile *File, unsigned Line,
-                                  DITypeRef Type, unsigned Arg, DIFlags Flags,
+                                  DIType *Type, unsigned Arg, DIFlags Flags,
                                   uint32_t AlignInBits, StorageType Storage,
                                   bool ShouldCreate = true) {
     return getImpl(Context, Scope, getCanonicalMDString(Context, Name), File,
@@ -2776,8 +2730,8 @@
 public:
   DEFINE_MDNODE_GET(DILocalVariable,
                     (DILocalScope * Scope, StringRef Name, DIFile *File,
-                     unsigned Line, DITypeRef Type, unsigned Arg,
-                     DIFlags Flags, uint32_t AlignInBits),
+                     unsigned Line, DIType *Type, unsigned Arg, DIFlags Flags,
+                     uint32_t AlignInBits),
                     (Scope, Name, File, Line, Type, Arg, Flags, AlignInBits))
   DEFINE_MDNODE_GET(DILocalVariable,
                     (Metadata * Scope, MDString *Name, Metadata *File,
@@ -2902,7 +2856,7 @@
   static DIObjCProperty *
   getImpl(LLVMContext &Context, StringRef Name, DIFile *File, unsigned Line,
           StringRef GetterName, StringRef SetterName, unsigned Attributes,
-          DITypeRef Type, StorageType Storage, bool ShouldCreate = true) {
+          DIType *Type, StorageType Storage, bool ShouldCreate = true) {
     return getImpl(Context, getCanonicalMDString(Context, Name), File, Line,
                    getCanonicalMDString(Context, GetterName),
                    getCanonicalMDString(Context, SetterName), Attributes, Type,
@@ -2924,7 +2878,7 @@
   DEFINE_MDNODE_GET(DIObjCProperty,
                     (StringRef Name, DIFile *File, unsigned Line,
                      StringRef GetterName, StringRef SetterName,
-                     unsigned Attributes, DITypeRef Type),
+                     unsigned Attributes, DIType *Type),
                     (Name, File, Line, GetterName, SetterName, Attributes,
                      Type))
   DEFINE_MDNODE_GET(DIObjCProperty,
@@ -2942,7 +2896,7 @@
   DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
   StringRef getGetterName() const { return getStringOperand(2); }
   StringRef getSetterName() const { return getStringOperand(3); }
-  DITypeRef getType() const { return DITypeRef(getRawType()); }
+  DIType *getType() const { return cast_or_null<DIType>(getRawType()); }
 
   StringRef getFilename() const {
     if (auto *F = getFile())
@@ -2986,8 +2940,8 @@
   ~DIImportedEntity() = default;
 
   static DIImportedEntity *getImpl(LLVMContext &Context, unsigned Tag,
-                                   DIScope *Scope, DINodeRef Entity,
-                                   DIFile *File, unsigned Line, StringRef Name,
+                                   DIScope *Scope, DINode *Entity, DIFile *File,
+                                   unsigned Line, StringRef Name,
                                    StorageType Storage,
                                    bool ShouldCreate = true) {
     return getImpl(Context, Tag, Scope, Entity, File, Line,
@@ -3006,8 +2960,8 @@
 
 public:
   DEFINE_MDNODE_GET(DIImportedEntity,
-                    (unsigned Tag, DIScope *Scope, DINodeRef Entity,
-                     DIFile *File, unsigned Line, StringRef Name = ""),
+                    (unsigned Tag, DIScope *Scope, DINode *Entity, DIFile *File,
+                     unsigned Line, StringRef Name = ""),
                     (Tag, Scope, Entity, File, Line, Name))
   DEFINE_MDNODE_GET(DIImportedEntity,
                     (unsigned Tag, Metadata *Scope, Metadata *Entity,
@@ -3018,7 +2972,7 @@
 
   unsigned getLine() const { return Line; }
   DIScope *getScope() const { return cast_or_null<DIScope>(getRawScope()); }
-  DINodeRef getEntity() const { return DINodeRef(getRawEntity()); }
+  DINode *getEntity() const { return cast_or_null<DINode>(getRawEntity()); }
   StringRef getName() const { return getStringOperand(2); }
   DIFile *getFile() const { return cast_or_null<DIFile>(getRawFile()); }
 
Index: lib/Bitcode/Reader/MetadataLoader.cpp
===================================================================
--- lib/Bitcode/Reader/MetadataLoader.cpp
+++ lib/Bitcode/Reader/MetadataLoader.cpp
@@ -337,7 +337,7 @@
   if (!Tuple || Tuple->isDistinct())
     return MaybeTuple;
 
-  // Look through the DITypeRefArray, upgrading each DITypeRef.
+  // Look through the DITypeRefArray, upgrading each DIType *.
   SmallVector<Metadata *, 32> Ops;
   Ops.reserve(Tuple->getNumOperands());
   for (Metadata *MD : Tuple->operands())
Index: lib/CodeGen/AsmPrinter/CodeViewDebug.h
===================================================================
--- lib/CodeGen/AsmPrinter/CodeViewDebug.h
+++ lib/CodeGen/AsmPrinter/CodeViewDebug.h
@@ -373,14 +373,14 @@
 
   /// Translates the DIType to codeview if necessary and returns a type index
   /// for it.
-  codeview::TypeIndex getTypeIndex(DITypeRef TypeRef,
-                                   DITypeRef ClassTyRef = DITypeRef());
+  codeview::TypeIndex getTypeIndex(const DIType *Ty,
+                                   const DIType *ClassTy = nullptr);
 
   codeview::TypeIndex
   getTypeIndexForThisPtr(const DIDerivedType *PtrTy,
                          const DISubroutineType *SubroutineTy);
 
-  codeview::TypeIndex getTypeIndexForReferenceTo(DITypeRef TypeRef);
+  codeview::TypeIndex getTypeIndexForReferenceTo(const DIType *Ty);
 
   codeview::TypeIndex getMemberFunctionType(const DISubprogram *SP,
                                             const DICompositeType *Class);
@@ -419,7 +419,7 @@
   /// use this entry point when generating symbol records. The complete and
   /// incomplete type indices only differ for record types. All other types use
   /// the same index.
-  codeview::TypeIndex getCompleteTypeIndex(DITypeRef TypeRef);
+  codeview::TypeIndex getCompleteTypeIndex(const DIType *Ty);
 
   codeview::TypeIndex lowerCompleteTypeClass(const DICompositeType *Ty);
   codeview::TypeIndex lowerCompleteTypeUnion(const DICompositeType *Ty);
Index: lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
+++ lib/CodeGen/AsmPrinter/CodeViewDebug.cpp
@@ -272,7 +272,7 @@
     StringRef ScopeName = getPrettyScopeName(Scope);
     if (!ScopeName.empty())
       QualifiedNameComponents.push_back(ScopeName);
-    Scope = Scope->getScope().resolve();
+    Scope = Scope->getScope();
   }
   return ClosestSubprogram;
 }
@@ -308,7 +308,7 @@
 };
 
 static std::string getFullyQualifiedName(const DIScope *Ty) {
-  const DIScope *Scope = Ty->getScope().resolve();
+  const DIScope *Scope = Ty->getScope();
   return getFullyQualifiedName(Scope, getPrettyScopeName(Ty));
 }
 
@@ -343,7 +343,7 @@
   // MSVC.
   StringRef DisplayName = SP->getName().split('<').first;
 
-  const DIScope *Scope = SP->getScope().resolve();
+  const DIScope *Scope = SP->getScope();
   TypeIndex TI;
   if (const auto *Class = dyn_cast_or_null<DICompositeType>(Scope)) {
     // If the scope is a DICompositeType, then this must be a method. Member
@@ -375,7 +375,7 @@
   const DIType *ReturnTy = nullptr;
   if (auto TypeArray = Ty->getTypeArray()) {
     if (TypeArray.size())
-      ReturnTy = TypeArray[0].resolve();
+      ReturnTy = TypeArray[0];
   }
 
   if (auto *ReturnDCTy = dyn_cast_or_null<DICompositeType>(ReturnTy)) {
@@ -974,8 +974,7 @@
   // If we have a display name, build the fully qualified name by walking the
   // chain of scopes.
   if (!SP->getName().empty())
-    FuncName =
-        getFullyQualifiedName(SP->getScope().resolve(), SP->getName());
+    FuncName = getFullyQualifiedName(SP->getScope(), SP->getName());
 
   // If our DISubprogram name is empty, use the mangled name.
   if (FuncName.empty())
@@ -1398,7 +1397,7 @@
 
   // MSVC does not emit UDTs for typedefs that are scoped to classes.
   if (T->getTag() == dwarf::DW_TAG_typedef) {
-    if (DIScope *Scope = T->getScope().resolve()) {
+    if (DIScope *Scope = T->getScope()) {
       switch (Scope->getTag()) {
       case dwarf::DW_TAG_structure_type:
       case dwarf::DW_TAG_class_type:
@@ -1415,7 +1414,7 @@
     const DIDerivedType *DT = dyn_cast<DIDerivedType>(T);
     if (!DT)
       return true;
-    T = DT->getBaseType().resolve();
+    T = DT->getBaseType();
   }
   return true;
 }
@@ -1428,8 +1427,8 @@
     return;
 
   SmallVector<StringRef, 5> QualifiedNameComponents;
-  const DISubprogram *ClosestSubprogram = getQualifiedNameComponents(
-      Ty->getScope().resolve(), QualifiedNameComponents);
+  const DISubprogram *ClosestSubprogram =
+      getQualifiedNameComponents(Ty->getScope(), QualifiedNameComponents);
 
   std::string FullyQualifiedName =
       getQualifiedName(QualifiedNameComponents, getPrettyScopeName(Ty));
@@ -1498,8 +1497,7 @@
 }
 
 TypeIndex CodeViewDebug::lowerTypeAlias(const DIDerivedType *Ty) {
-  DITypeRef UnderlyingTypeRef = Ty->getBaseType();
-  TypeIndex UnderlyingTypeIndex = getTypeIndex(UnderlyingTypeRef);
+  TypeIndex UnderlyingTypeIndex = getTypeIndex(Ty->getBaseType());
   StringRef TypeName = Ty->getName();
 
   addToUDTs(Ty);
@@ -1515,14 +1513,14 @@
 }
 
 TypeIndex CodeViewDebug::lowerTypeArray(const DICompositeType *Ty) {
-  DITypeRef ElementTypeRef = Ty->getBaseType();
-  TypeIndex ElementTypeIndex = getTypeIndex(ElementTypeRef);
+  const DIType *ElementType = Ty->getBaseType();
+  TypeIndex ElementTypeIndex = getTypeIndex(ElementType);
   // IndexType is size_t, which depends on the bitness of the target.
   TypeIndex IndexType = getPointerSizeInBytes() == 8
                             ? TypeIndex(SimpleTypeKind::UInt64Quad)
                             : TypeIndex(SimpleTypeKind::UInt32Long);
 
-  uint64_t ElementSize = getBaseTypeSize(ElementTypeRef) / 8;
+  uint64_t ElementSize = getBaseTypeSize(ElementType) / 8;
 
   // Add subranges to array type.
   DINodeArray Elements = Ty->getElements();
@@ -1783,7 +1781,7 @@
       break;
     }
     if (IsModifier)
-      BaseTy = cast<DIDerivedType>(BaseTy)->getBaseType().resolve();
+      BaseTy = cast<DIDerivedType>(BaseTy)->getBaseType();
   }
 
   // Check if the inner type will use an LF_POINTER record. If so, the
@@ -1816,8 +1814,8 @@
 
 TypeIndex CodeViewDebug::lowerTypeFunction(const DISubroutineType *Ty) {
   SmallVector<TypeIndex, 8> ReturnAndArgTypeIndices;
-  for (DITypeRef ArgTypeRef : Ty->getTypeArray())
-    ReturnAndArgTypeIndices.push_back(getTypeIndex(ArgTypeRef));
+  for (const DIType *ArgType : Ty->getTypeArray())
+    ReturnAndArgTypeIndices.push_back(getTypeIndex(ArgType));
 
   // MSVC uses type none for variadic argument.
   if (ReturnAndArgTypeIndices.size() > 1 &&
@@ -1866,7 +1864,7 @@
   TypeIndex ThisTypeIndex;
   if (!IsStaticMethod && ReturnAndArgs.size() > Index) {
     if (const DIDerivedType *PtrTy =
-            dyn_cast_or_null<DIDerivedType>(ReturnAndArgs[Index].resolve())) {
+            dyn_cast_or_null<DIDerivedType>(ReturnAndArgs[Index])) {
       if (PtrTy->getTag() == dwarf::DW_TAG_pointer_type) {
         ThisTypeIndex = getTypeIndexForThisPtr(PtrTy, Ty);
         Index++;
@@ -1964,7 +1962,7 @@
   // Put the Nested flag on a type if it appears immediately inside a tag type.
   // Do not walk the scope chain. Do not attempt to compute ContainsNestedClass
   // here. That flag is only set on definitions, and not forward declarations.
-  const DIScope *ImmediateScope = Ty->getScope().resolve();
+  const DIScope *ImmediateScope = Ty->getScope();
   if (ImmediateScope && isa<DICompositeType>(ImmediateScope))
     CO |= ClassOptions::Nested;
 
@@ -1977,7 +1975,7 @@
       CO |= ClassOptions::Scoped;
   } else {
     for (const DIScope *Scope = ImmediateScope; Scope != nullptr;
-         Scope = Scope->getScope().resolve()) {
+         Scope = Scope->getScope()) {
       if (isa<DISubprogram>(Scope)) {
         CO |= ClassOptions::Scoped;
         break;
@@ -2097,7 +2095,7 @@
   // succeeds, and drop the member if that fails.
   assert((DDTy->getOffsetInBits() % 8) == 0 && "Unnamed bitfield member!");
   uint64_t Offset = DDTy->getOffsetInBits();
-  const DIType *Ty = DDTy->getBaseType().resolve();
+  const DIType *Ty = DDTy->getBaseType();
   bool FullyResolved = false;
   while (!FullyResolved) {
     switch (Ty->getTag()) {
@@ -2105,7 +2103,7 @@
     case dwarf::DW_TAG_volatile_type:
       // FIXME: we should apply the qualifier types to the indirect fields
       // rather than dropping them.
-      Ty = cast<DIDerivedType>(Ty)->getBaseType().resolve();
+      Ty = cast<DIDerivedType>(Ty)->getBaseType();
       break;
     default:
       FullyResolved = true;
@@ -2388,7 +2386,7 @@
 
   // Create nested classes.
   for (const DIType *Nested : Info.NestedTypes) {
-    NestedTypeRecord R(getTypeIndex(DITypeRef(Nested)), Nested->getName());
+    NestedTypeRecord R(getTypeIndex(Nested), Nested->getName());
     ContinuationBuilder.writeMemberType(R);
     MemberCount++;
   }
@@ -2415,10 +2413,7 @@
   return VBPType;
 }
 
-TypeIndex CodeViewDebug::getTypeIndex(DITypeRef TypeRef, DITypeRef ClassTyRef) {
-  const DIType *Ty = TypeRef.resolve();
-  const DIType *ClassTy = ClassTyRef.resolve();
-
+TypeIndex CodeViewDebug::getTypeIndex(const DIType *Ty, const DIType *ClassTy) {
   // The null DIType is the void type. Don't try to hash it.
   if (!Ty)
     return TypeIndex::Void();
@@ -2461,8 +2456,7 @@
   return recordTypeIndexForDINode(PtrTy, TI, SubroutineTy);
 }
 
-TypeIndex CodeViewDebug::getTypeIndexForReferenceTo(DITypeRef TypeRef) {
-  DIType *Ty = TypeRef.resolve();
+TypeIndex CodeViewDebug::getTypeIndexForReferenceTo(const DIType *Ty) {
   PointerRecord PR(getTypeIndex(Ty),
                    getPointerSizeInBytes() == 8 ? PointerKind::Near64
                                                 : PointerKind::Near32,
@@ -2471,9 +2465,7 @@
   return TypeTable.writeLeafType(PR);
 }
 
-TypeIndex CodeViewDebug::getCompleteTypeIndex(DITypeRef TypeRef) {
-  const DIType *Ty = TypeRef.resolve();
-
+TypeIndex CodeViewDebug::getCompleteTypeIndex(const DIType *Ty) {
   // The null DIType is the void type. Don't try to hash it.
   if (!Ty)
     return TypeIndex::Void();
@@ -2484,7 +2476,7 @@
   if (Ty->getTag() == dwarf::DW_TAG_typedef)
     (void)getTypeIndex(Ty);
   while (Ty->getTag() == dwarf::DW_TAG_typedef)
-    Ty = cast<DIDerivedType>(Ty)->getBaseType().resolve();
+    Ty = cast<DIDerivedType>(Ty)->getBaseType();
 
   // If this is a non-record type, the complete type index is the same as the
   // normal type index. Just call getTypeIndex.
Index: lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
+++ lib/CodeGen/AsmPrinter/DebugHandlerBase.cpp
@@ -140,10 +140,9 @@
 }
 
 /// If this type is derived from a base type then return base type size.
-uint64_t DebugHandlerBase::getBaseTypeSize(const DITypeRef TyRef) {
-  DIType *Ty = TyRef.resolve();
+uint64_t DebugHandlerBase::getBaseTypeSize(const DIType *Ty) {
   assert(Ty);
-  DIDerivedType *DDTy = dyn_cast<DIDerivedType>(Ty);
+  const DIDerivedType *DDTy = dyn_cast<DIDerivedType>(Ty);
   if (!DDTy)
     return Ty->getSizeInBits();
 
@@ -154,7 +153,7 @@
       Tag != dwarf::DW_TAG_restrict_type && Tag != dwarf::DW_TAG_atomic_type)
     return DDTy->getSizeInBits();
 
-  DIType *BaseType = DDTy->getBaseType().resolve();
+  DIType *BaseType = DDTy->getBaseType();
 
   if (!BaseType)
     return 0;
Index: lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
+++ lib/CodeGen/AsmPrinter/DwarfCompileUnit.cpp
@@ -119,7 +119,7 @@
   assert(GV);
 
   auto *GVContext = GV->getScope();
-  auto *GTy = DD->resolve(GV->getType());
+  const DIType *GTy = GV->getType();
 
   // Construct the context before querying for the existence of the DIE in
   // case such construction creates the DIE.
@@ -131,7 +131,7 @@
   DIE *VariableDIE = &createAndAddDIE(GV->getTag(), *ContextDIE, GV);
   DIScope *DeclContext;
   if (auto *SDMDecl = GV->getStaticDataMemberDeclaration()) {
-    DeclContext = resolve(SDMDecl->getScope());
+    DeclContext = SDMDecl->getScope();
     assert(SDMDecl->isStaticMember() && "Expected static member decl");
     assert(GV->isDefinition());
     // We need the declaration DIE that is in the static member's class.
@@ -139,7 +139,7 @@
     addDIEEntry(*VariableDIE, dwarf::DW_AT_specification, *VariableSpecDIE);
     // If the global variable's type is different from the one in the class
     // member type, assume that it's more specific and also emit it.
-    if (GTy != DD->resolve(SDMDecl->getBaseType()))
+    if (GTy != SDMDecl->getBaseType())
       addType(*VariableDIE, GTy);
   } else {
     DeclContext = GV->getScope();
@@ -878,7 +878,7 @@
     ContextDIE = &getUnitDie();
     getOrCreateSubprogramDIE(SPDecl);
   } else {
-    ContextDIE = getOrCreateContextDIE(resolve(SP->getScope()));
+    ContextDIE = getOrCreateContextDIE(SP->getScope());
     // The scope may be shared with a subprogram that has already been
     // constructed in another CU, in which case we need to construct this
     // subprogram in the same CU.
@@ -927,7 +927,7 @@
   DIE *IMDie = DIE::get(DIEValueAllocator, (dwarf::Tag)Module->getTag());
   insertDIE(Module, IMDie);
   DIE *EntityDie;
-  auto *Entity = resolve(Module->getEntity());
+  auto *Entity = Module->getEntity();
   if (auto *NS = dyn_cast<DINamespace>(Entity))
     EntityDie = getOrCreateNameSpace(NS);
   else if (auto *M = dyn_cast<DIModule>(Entity))
@@ -1192,7 +1192,7 @@
 void DwarfCompileUnit::applySubprogramAttributesToDefinition(
     const DISubprogram *SP, DIE &SPDie) {
   auto *SPDecl = SP->getDeclaration();
-  auto *Context = resolve(SPDecl ? SPDecl->getScope() : SP->getScope());
+  auto *Context = SPDecl ? SPDecl->getScope() : SP->getScope();
   applySubprogramAttributes(SP, SPDie, includeMinimalInlineScopes());
   addGlobalName(SP->getName(), SPDie, Context);
 }
Index: lib/CodeGen/AsmPrinter/DwarfDebug.h
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfDebug.h
+++ lib/CodeGen/AsmPrinter/DwarfDebug.h
@@ -218,11 +218,6 @@
   static bool classof(const DbgEntity *N) {
     return N->getDbgEntityID() == DbgVariableKind;
   }
-
-private:
-  template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {
-    return Ref.resolve();
-  }
 };
 
 //===----------------------------------------------------------------------===//
@@ -253,11 +248,6 @@
   static bool classof(const DbgEntity *N) {
     return N->getDbgEntityID() == DbgLabelKind;
   }
-
-private:
-  template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {
-    return Ref.resolve();
-  }
 };
 
 /// Helper used to pair up a symbol and its DWARF compile unit.
@@ -702,11 +692,6 @@
   void emitDebugLocEntryLocation(const DebugLocStream::Entry &Entry,
                                  const DwarfCompileUnit *CU);
 
-  /// Find the MDNode for the given reference.
-  template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {
-    return Ref.resolve();
-  }
-
   void addSubprogramNames(const DICompileUnit &CU, const DISubprogram *SP,
                           DIE &Die);
 
Index: lib/CodeGen/AsmPrinter/DwarfDebug.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfDebug.cpp
+++ lib/CodeGen/AsmPrinter/DwarfDebug.cpp
@@ -196,11 +196,11 @@
 
 bool DbgVariable::isBlockByrefVariable() const {
   assert(getVariable() && "Invalid complex DbgVariable!");
-  return getVariable()->getType().resolve()->isBlockByrefStruct();
+  return getVariable()->getType()->isBlockByrefStruct();
 }
 
 const DIType *DbgVariable::getType() const {
-  DIType *Ty = getVariable()->getType().resolve();
+  DIType *Ty = getVariable()->getType();
   // FIXME: isBlockByrefVariable should be reformulated in terms of complex
   // addresses instead.
   if (Ty->isBlockByrefStruct()) {
@@ -232,13 +232,13 @@
     uint16_t tag = Ty->getTag();
 
     if (tag == dwarf::DW_TAG_pointer_type)
-      subType = resolve(cast<DIDerivedType>(Ty)->getBaseType());
+      subType = cast<DIDerivedType>(Ty)->getBaseType();
 
     auto Elements = cast<DICompositeType>(subType)->getElements();
     for (unsigned i = 0, N = Elements.size(); i < N; ++i) {
       auto *DT = cast<DIDerivedType>(Elements[i]);
       if (getName() == DT->getName())
-        return resolve(DT->getBaseType());
+        return DT->getBaseType();
     }
   }
   return Ty;
Index: lib/CodeGen/AsmPrinter/DwarfUnit.h
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfUnit.h
+++ lib/CodeGen/AsmPrinter/DwarfUnit.h
@@ -311,12 +311,6 @@
   /// create a new ID and insert it in the line table.
   virtual unsigned getOrCreateSourceID(const DIFile *File) = 0;
 
-  /// Look in the DwarfDebug map for the MDNode that corresponds to the
-  /// reference.
-  template <typename T> T *resolve(TypedDINodeRef<T> Ref) const {
-    return Ref.resolve();
-  }
-
   /// Emit the common part of the header for this unit.
   void emitCommonHeader(bool UseOffsets, dwarf::UnitType UT);
 
Index: lib/CodeGen/AsmPrinter/DwarfUnit.cpp
===================================================================
--- lib/CodeGen/AsmPrinter/DwarfUnit.cpp
+++ lib/CodeGen/AsmPrinter/DwarfUnit.cpp
@@ -471,9 +471,8 @@
     assert(T == dwarf::DW_TAG_typedef || T == dwarf::DW_TAG_const_type ||
            T == dwarf::DW_TAG_volatile_type ||
            T == dwarf::DW_TAG_restrict_type || T == dwarf::DW_TAG_atomic_type);
-    DITypeRef Deriv = DTy->getBaseType();
-    assert(Deriv && "Expected valid base type");
-    return isUnsignedDIType(DD, DD->resolve(Deriv));
+    assert(DTy->getBaseType() && "Expected valid base type");
+    return isUnsignedDIType(DD, DTy->getBaseType());
   }
 
   auto *BTy = cast<DIBasicType>(Ty);
@@ -613,7 +612,7 @@
 }
 
 DIE *DwarfUnit::createTypeDIE(const DICompositeType *Ty) {
-  auto *Context = resolve(Ty->getScope());
+  auto *Context = Ty->getScope();
   DIE *ContextDIE = getOrCreateContextDIE(Context);
 
   if (DIE *TyDIE = getDIE(Ty))
@@ -666,15 +665,15 @@
 
   // DW_TAG_restrict_type is not supported in DWARF2
   if (Ty->getTag() == dwarf::DW_TAG_restrict_type && DD->getDwarfVersion() <= 2)
-    return getOrCreateTypeDIE(resolve(cast<DIDerivedType>(Ty)->getBaseType()));
+    return getOrCreateTypeDIE(cast<DIDerivedType>(Ty)->getBaseType());
 
   // DW_TAG_atomic_type is not supported in DWARF < 5
   if (Ty->getTag() == dwarf::DW_TAG_atomic_type && DD->getDwarfVersion() < 5)
-    return getOrCreateTypeDIE(resolve(cast<DIDerivedType>(Ty)->getBaseType()));
+    return getOrCreateTypeDIE(cast<DIDerivedType>(Ty)->getBaseType());
 
   // Construct the context before querying for the existence of the DIE in case
   // such construction creates the DIE.
-  auto *Context = resolve(Ty->getScope());
+  auto *Context = Ty->getScope();
   DIE *ContextDIE = getOrCreateContextDIE(Context);
   assert(ContextDIE);
 
@@ -721,8 +720,8 @@
   SmallVector<const DIScope *, 1> Parents;
   while (!isa<DICompileUnit>(Context)) {
     Parents.push_back(Context);
-    if (Context->getScope())
-      Context = resolve(Context->getScope());
+    if (const DIScope *S = Context->getScope())
+      Context = S;
     else
       // Structure, etc types will have a NULL context if they're at the top
       // level.
@@ -773,7 +772,7 @@
   uint16_t Tag = Buffer.getTag();
 
   // Map to main type, void will not have a type.
-  const DIType *FromTy = resolve(DTy->getBaseType());
+  const DIType *FromTy = DTy->getBaseType();
   if (FromTy)
     addType(Buffer, FromTy);
 
@@ -789,9 +788,8 @@
     addUInt(Buffer, dwarf::DW_AT_byte_size, None, Size);
 
   if (Tag == dwarf::DW_TAG_ptr_to_member_type)
-    addDIEEntry(
-        Buffer, dwarf::DW_AT_containing_type,
-        *getOrCreateTypeDIE(resolve(cast<DIDerivedType>(DTy)->getClassType())));
+    addDIEEntry(Buffer, dwarf::DW_AT_containing_type,
+                *getOrCreateTypeDIE(cast<DIDerivedType>(DTy)->getClassType()));
   // Add source line info if available and TyDesc is not a forward declaration.
   if (!DTy->isForwardDecl())
     addSourceLine(Buffer, DTy);
@@ -806,7 +804,7 @@
 
 void DwarfUnit::constructSubprogramArguments(DIE &Buffer, DITypeRefArray Args) {
   for (unsigned i = 1, N = Args.size(); i < N; ++i) {
-    const DIType *Ty = resolve(Args[i]);
+    const DIType *Ty = Args[i];
     if (!Ty) {
       assert(i == N-1 && "Unspecified parameter must be the last argument");
       createAndAddDIE(dwarf::DW_TAG_unspecified_parameters, Buffer);
@@ -823,7 +821,7 @@
   // Add return type.  A void return won't have a type.
   auto Elements = cast<DISubroutineType>(CTy)->getTypeArray();
   if (Elements.size())
-    if (auto RTy = resolve(Elements[0]))
+    if (auto RTy = Elements[0])
       addType(Buffer, RTy);
 
   bool isPrototyped = true;
@@ -894,7 +892,7 @@
       else if (auto *DDTy = dyn_cast<DIDerivedType>(Element)) {
         if (DDTy->getTag() == dwarf::DW_TAG_friend) {
           DIE &ElemDie = createAndAddDIE(dwarf::DW_TAG_friend, Buffer);
-          addType(ElemDie, resolve(DDTy->getBaseType()), dwarf::DW_AT_friend);
+          addType(ElemDie, DDTy->getBaseType(), dwarf::DW_AT_friend);
         } else if (DDTy->isStaticMember()) {
           getOrCreateStaticMemberDIE(DDTy);
         } else if (Tag == dwarf::DW_TAG_variant_part) {
@@ -903,7 +901,7 @@
           DIE &Variant = createAndAddDIE(dwarf::DW_TAG_variant, Buffer);
           if (const ConstantInt *CI =
               dyn_cast_or_null<ConstantInt>(DDTy->getDiscriminantValue())) {
-            if (isUnsignedDIType(DD, resolve(Discriminator->getBaseType())))
+            if (isUnsignedDIType(DD, Discriminator->getBaseType()))
               addUInt(Variant, dwarf::DW_AT_discr_value, None, CI->getZExtValue());
             else
               addSInt(Variant, dwarf::DW_AT_discr_value, None, CI->getSExtValue());
@@ -917,7 +915,7 @@
         StringRef PropertyName = Property->getName();
         addString(ElemDie, dwarf::DW_AT_APPLE_property_name, PropertyName);
         if (Property->getType())
-          addType(ElemDie, resolve(Property->getType()));
+          addType(ElemDie, Property->getType());
         addSourceLine(ElemDie, Property);
         StringRef GetterName = Property->getGetterName();
         if (!GetterName.empty())
@@ -943,7 +941,7 @@
     // inside C++ composite types to point to the base class with the vtable.
     // Rust uses DW_AT_containing_type to link a vtable to the type
     // for which it was created.
-    if (auto *ContainingType = resolve(CTy->getVTableHolder()))
+    if (auto *ContainingType = CTy->getVTableHolder())
       addDIEEntry(Buffer, dwarf::DW_AT_containing_type,
                   *getOrCreateTypeDIE(ContainingType));
 
@@ -1013,7 +1011,7 @@
       createAndAddDIE(dwarf::DW_TAG_template_type_parameter, Buffer);
   // Add the type if it exists, it could be void and therefore no type.
   if (TP->getType())
-    addType(ParamDIE, resolve(TP->getType()));
+    addType(ParamDIE, TP->getType());
   if (!TP->getName().empty())
     addString(ParamDIE, dwarf::DW_AT_name, TP->getName());
 }
@@ -1025,12 +1023,12 @@
   // Add the type if there is one, template template and template parameter
   // packs will not have a type.
   if (VP->getTag() == dwarf::DW_TAG_template_value_parameter)
-    addType(ParamDIE, resolve(VP->getType()));
+    addType(ParamDIE, VP->getType());
   if (!VP->getName().empty())
     addString(ParamDIE, dwarf::DW_AT_name, VP->getName());
   if (Metadata *Val = VP->getValue()) {
     if (ConstantInt *CI = mdconst::dyn_extract<ConstantInt>(Val))
-      addConstantValue(ParamDIE, CI, resolve(VP->getType()));
+      addConstantValue(ParamDIE, CI, VP->getType());
     else if (GlobalValue *GV = mdconst::dyn_extract<GlobalValue>(Val)) {
       // We cannot describe the location of dllimport'd entities: the
       // computation of their address requires loads from the IAT.
@@ -1104,7 +1102,7 @@
   // such construction creates the DIE (as is the case for member function
   // declarations).
   DIE *ContextDIE =
-      Minimal ? &getUnitDie() : getOrCreateContextDIE(resolve(SP->getScope()));
+      Minimal ? &getUnitDie() : getOrCreateContextDIE(SP->getScope());
 
   if (DIE *SPDie = getDIE(SP))
     return SPDie;
@@ -1217,7 +1215,7 @@
   // Add a return type. If this is a type like a C/C++ void type we don't add a
   // return type.
   if (Args.size())
-    if (auto Ty = resolve(Args[0]))
+    if (auto Ty = Args[0])
       addType(SPDie, Ty);
 
   unsigned VK = SP->getVirtuality();
@@ -1229,8 +1227,7 @@
       addUInt(*Block, dwarf::DW_FORM_udata, SP->getVirtualIndex());
       addBlock(SPDie, dwarf::DW_AT_vtable_elem_location, Block);
     }
-    ContainingTypeMap.insert(
-        std::make_pair(&SPDie, resolve(SP->getContainingType())));
+    ContainingTypeMap.insert(std::make_pair(&SPDie, SP->getContainingType()));
   }
 
   if (!SP->isDefinition()) {
@@ -1336,7 +1333,7 @@
   const uint64_t ActualSize = CTy->getSizeInBits();
 
   // Obtain the size of each element in the vector.
-  DIType *BaseTy = CTy->getBaseType().resolve();
+  DIType *BaseTy = CTy->getBaseType();
   assert(BaseTy && "Unknown vector element type.");
   const uint64_t ElementSize = BaseTy->getSizeInBits();
 
@@ -1364,7 +1361,7 @@
   }
 
   // Emit the element type.
-  addType(Buffer, resolve(CTy->getBaseType()));
+  addType(Buffer, CTy->getBaseType());
 
   // Get an anonymous type for index type.
   // FIXME: This type should be passed down from the front end
@@ -1382,7 +1379,7 @@
 }
 
 void DwarfUnit::constructEnumTypeDIE(DIE &Buffer, const DICompositeType *CTy) {
-  const DIType *DTy = resolve(CTy->getBaseType());
+  const DIType *DTy = CTy->getBaseType();
   bool IsUnsigned = DTy && isUnsignedDIType(DD, DTy);
   if (DTy) {
     if (DD->getDwarfVersion() >= 3)
@@ -1426,7 +1423,7 @@
   if (!Name.empty())
     addString(MemberDie, dwarf::DW_AT_name, Name);
 
-  if (DIType *Resolved = resolve(DT->getBaseType()))
+  if (DIType *Resolved = DT->getBaseType())
     addType(MemberDie, Resolved);
 
   addSourceLine(MemberDie, DT);
@@ -1535,7 +1532,7 @@
 
   // Construct the context before querying for the existence of the DIE in case
   // such construction creates the DIE.
-  DIE *ContextDIE = getOrCreateContextDIE(resolve(DT->getScope()));
+  DIE *ContextDIE = getOrCreateContextDIE(DT->getScope());
   assert(dwarf::isType(ContextDIE->getTag()) &&
          "Static member should belong to a type.");
 
@@ -1544,7 +1541,7 @@
 
   DIE &StaticMemberDIE = createAndAddDIE(DT->getTag(), *ContextDIE, DT);
 
-  const DIType *Ty = resolve(DT->getBaseType());
+  const DIType *Ty = DT->getBaseType();
 
   addString(StaticMemberDIE, dwarf::DW_AT_name, DT->getName());
   addType(StaticMemberDIE, Ty);
Index: lib/IR/DIBuilder.cpp
===================================================================
--- lib/IR/DIBuilder.cpp
+++ lib/IR/DIBuilder.cpp
@@ -166,8 +166,8 @@
   if (Line)
     assert(File && "Source location has line number but no file");
   unsigned EntitiesCount = C.pImpl->DIImportedEntitys.size();
-  auto *M =
-      DIImportedEntity::get(C, Tag, Context, DINodeRef(NS), File, Line, Name);
+  auto *M = DIImportedEntity::get(C, Tag, Context, cast_or_null<DINode>(NS),
+                                  File, Line, Name);
   if (EntitiesCount < C.pImpl->DIImportedEntitys.size())
     // A new Imported Entity was just added to the context.
     // Add it to the Imported Modules list.
Index: lib/IR/DebugInfo.cpp
===================================================================
--- lib/IR/DebugInfo.cpp
+++ lib/IR/DebugInfo.cpp
@@ -81,7 +81,7 @@
       continue;
     auto *GV = DIG->getVariable();
     processScope(GV->getScope());
-    processType(GV->getType().resolve());
+    processType(GV->getType());
   }
   for (auto *ET : CU->getEnumTypes())
     processType(ET);
@@ -91,7 +91,7 @@
     else
       processSubprogram(cast<DISubprogram>(RT));
   for (auto *Import : CU->getImportedEntities()) {
-    auto *Entity = Import->getEntity().resolve();
+    auto *Entity = Import->getEntity();
     if (auto *T = dyn_cast<DIType>(Entity))
       processType(T);
     else if (auto *SP = dyn_cast<DISubprogram>(Entity))
@@ -124,14 +124,14 @@
 void DebugInfoFinder::processType(DIType *DT) {
   if (!addType(DT))
     return;
-  processScope(DT->getScope().resolve());
+  processScope(DT->getScope());
   if (auto *ST = dyn_cast<DISubroutineType>(DT)) {
-    for (DITypeRef Ref : ST->getTypeArray())
-      processType(Ref.resolve());
+    for (DIType *Ref : ST->getTypeArray())
+      processType(Ref);
     return;
   }
   if (auto *DCT = dyn_cast<DICompositeType>(DT)) {
-    processType(DCT->getBaseType().resolve());
+    processType(DCT->getBaseType());
     for (Metadata *D : DCT->getElements()) {
       if (auto *T = dyn_cast<DIType>(D))
         processType(T);
@@ -141,7 +141,7 @@
     return;
   }
   if (auto *DDT = dyn_cast<DIDerivedType>(DT)) {
-    processType(DDT->getBaseType().resolve());
+    processType(DDT->getBaseType());
   }
 }
 
@@ -174,7 +174,7 @@
 void DebugInfoFinder::processSubprogram(DISubprogram *SP) {
   if (!addSubprogram(SP))
     return;
-  processScope(SP->getScope().resolve());
+  processScope(SP->getScope());
   // Some of the users, e.g. CloneFunctionInto / CloneModule, need to set up a
   // ValueMap containing identity mappings for all of the DICompileUnit's, not
   // just DISubprogram's, referenced from anywhere within the Function being
@@ -187,9 +187,9 @@
   processType(SP->getType());
   for (auto *Element : SP->getTemplateParams()) {
     if (auto *TType = dyn_cast<DITemplateTypeParameter>(Element)) {
-      processType(TType->getType().resolve());
+      processType(TType->getType());
     } else if (auto *TVal = dyn_cast<DITemplateValueParameter>(Element)) {
-      processType(TVal->getType().resolve());
+      processType(TVal->getType());
     }
   }
 }
@@ -207,7 +207,7 @@
   if (!NodesSeen.insert(DV).second)
     return;
   processScope(DV->getScope());
-  processType(DV->getType().resolve());
+  processType(DV->getType());
 }
 
 void DebugInfoFinder::processValue(const Module &M, const DbgValueInst *DVI) {
@@ -222,7 +222,7 @@
   if (!NodesSeen.insert(DV).second)
     return;
   processScope(DV->getScope());
-  processType(DV->getType().resolve());
+  processType(DV->getType());
 }
 
 bool DebugInfoFinder::addType(DIType *DT) {
@@ -428,7 +428,8 @@
     StringRef LinkageName = MDS->getName().empty() ? MDS->getLinkageName() : "";
     DISubprogram *Declaration = nullptr;
     auto *Type = cast_or_null<DISubroutineType>(map(MDS->getType()));
-    DITypeRef ContainingType(map(MDS->getContainingType()));
+    DIType *ContainingType =
+        cast_or_null<DIType>(map(MDS->getContainingType()));
     auto *Unit = cast_or_null<DICompileUnit>(map(MDS->getUnit()));
     auto Variables = nullptr;
     auto TemplateParams = nullptr;
Index: lib/IR/DebugInfoMetadata.cpp
===================================================================
--- lib/IR/DebugInfoMetadata.cpp
+++ lib/IR/DebugInfoMetadata.cpp
@@ -88,7 +88,7 @@
   DILocation *L = LocA->getInlinedAt();
   while (S) {
     Locations.insert(std::make_pair(S, L));
-    S = S->getScope().resolve();
+    S = S->getScope();
     if (!S && L) {
       S = L->getScope();
       L = L->getInlinedAt();
@@ -100,7 +100,7 @@
   while (S) {
     if (Locations.count(std::make_pair(S, L)))
       break;
-    S = S->getScope().resolve();
+    S = S->getScope();
     if (!S && L) {
       S = L->getScope();
       L = L->getInlinedAt();
@@ -209,7 +209,7 @@
   return Flags;
 }
 
-DIScopeRef DIScope::getScope() const {
+DIScope *DIScope::getScope() const {
   if (auto *T = dyn_cast<DIType>(this))
     return T->getScope();
 
Index: lib/Target/BPF/BTFDebug.cpp
===================================================================
--- lib/Target/BPF/BTFDebug.cpp
+++ lib/Target/BPF/BTFDebug.cpp
@@ -65,7 +65,7 @@
   BTFType.NameOff = BDebug.addString(DTy->getName());
 
   // The base type for PTR/CONST/VOLATILE could be void.
-  const DIType *ResolvedType = DTy->getBaseType().resolve();
+  const DIType *ResolvedType = DTy->getBaseType();
   if (!ResolvedType) {
     assert((Kind == BTF::BTF_KIND_PTR || Kind == BTF::BTF_KIND_CONST ||
             Kind == BTF::BTF_KIND_VOLATILE) &&
@@ -209,7 +209,7 @@
     } else {
       BTFMember.Offset = DDTy->getOffsetInBits();
     }
-    BTFMember.Type = BDebug.getTypeId(DDTy->getBaseType().resolve());
+    BTFMember.Type = BDebug.getTypeId(DDTy->getBaseType());
     Members.push_back(BTFMember);
   }
 }
@@ -239,7 +239,7 @@
 
 void BTFTypeFuncProto::completeType(BTFDebug &BDebug) {
   DITypeRefArray Elements = STy->getTypeArray();
-  auto RetType = Elements[0].resolve();
+  auto RetType = Elements[0];
   BTFType.Type = RetType ? BDebug.getTypeId(RetType) : 0;
   BTFType.NameOff = 0;
 
@@ -247,7 +247,7 @@
   // to represent the vararg, encode the NameOff/Type to be 0.
   for (unsigned I = 1, N = Elements.size(); I < N; ++I) {
     struct BTF::BTFParam Param;
-    auto Element = Elements[I].resolve();
+    auto Element = Elements[I];
     if (Element) {
       Param.NameOff = BDebug.addString(FuncArgNames[I]);
       Param.Type = BDebug.getTypeId(Element);
@@ -393,7 +393,7 @@
 
   // Visit return type and func arg types.
   for (const auto Element : Elements) {
-    visitTypeEntry(Element.resolve());
+    visitTypeEntry(Element);
   }
 }
 
@@ -427,7 +427,7 @@
 void BTFDebug::visitArrayType(const DICompositeType *CTy, uint32_t &TypeId) {
   // Visit array element type.
   uint32_t ElemTypeId;
-  visitTypeEntry(CTy->getBaseType().resolve(), ElemTypeId);
+  visitTypeEntry(CTy->getBaseType(), ElemTypeId);
 
   if (!CTy->getSizeInBits()) {
     auto TypeEntry = llvm::make_unique<BTFTypeArray>(ElemTypeId, 0);
@@ -513,7 +513,7 @@
   // Visit base type of pointer, typedef, const, volatile, restrict or
   // struct/union member.
   uint32_t TempTypeId = 0;
-  visitTypeEntry(DTy->getBaseType().resolve(), TempTypeId);
+  visitTypeEntry(DTy->getBaseType(), TempTypeId);
 }
 
 void BTFDebug::visitTypeEntry(const DIType *Ty, uint32_t &TypeId) {
@@ -713,7 +713,7 @@
       // Collect function arguments for subprogram func type.
       uint32_t Arg = DV->getArg();
       if (Arg) {
-        visitTypeEntry(DV->getType().resolve());
+        visitTypeEntry(DV->getType());
         FuncArgNames[Arg] = DV->getName();
       }
     }
@@ -810,7 +810,7 @@
     Global.getDebugInfo(GVs);
     uint32_t GVTypeId = 0;
     for (auto *GVE : GVs) {
-      visitTypeEntry(GVE->getVariable()->getType().resolve(), GVTypeId);
+      visitTypeEntry(GVE->getVariable()->getType(), GVTypeId);
       break;
     }
 
Index: tools/opt/BreakpointPrinter.cpp
===================================================================
--- tools/opt/BreakpointPrinter.cpp
+++ tools/opt/BreakpointPrinter.cpp
@@ -35,7 +35,7 @@
       }
     } else if (auto *TY = dyn_cast<DIType>(Context)) {
       if (!TY->getName().empty()) {
-        getContextName(TY->getScope().resolve(), N);
+        getContextName(TY->getScope(), N);
         N = N + TY->getName().str() + "::";
       }
     }
@@ -49,7 +49,7 @@
         auto *SP = cast_or_null<DISubprogram>(NMD->getOperand(i));
         if (!SP)
           continue;
-        getContextName(SP->getScope().resolve(), Name);
+        getContextName(SP->getScope(), Name);
         Name = Name + SP->getName().str();
         if (!Name.empty() && Processed.insert(Name).second) {
           Out << Name << "\n";