diff --git a/clang/include/clang/AST/ASTContext.h b/clang/include/clang/AST/ASTContext.h
--- a/clang/include/clang/AST/ASTContext.h
+++ b/clang/include/clang/AST/ASTContext.h
@@ -1621,7 +1621,7 @@
                                         Decl *AssociatedDecl, unsigned Index,
                                         Optional<unsigned> PackIndex) const;
   QualType getSubstTemplateTypeParmPackType(Decl *AssociatedDecl,
-                                            unsigned Index,
+                                            unsigned Index, bool Final,
                                             const TemplateArgument &ArgPack);
 
   QualType
@@ -2208,7 +2208,8 @@
                                             Optional<unsigned> PackIndex) const;
   TemplateName getSubstTemplateTemplateParmPack(const TemplateArgument &ArgPack,
                                                 Decl *AssociatedDecl,
-                                                unsigned Index) const;
+                                                unsigned Index,
+                                                bool Final) const;
 
   enum GetBuiltinTypeError {
     /// No error
diff --git a/clang/include/clang/AST/PropertiesBase.td b/clang/include/clang/AST/PropertiesBase.td
--- a/clang/include/clang/AST/PropertiesBase.td
+++ b/clang/include/clang/AST/PropertiesBase.td
@@ -730,8 +730,11 @@
   def : Property<"index", UInt32> {
     let Read = [{ parm->getIndex() }];
   }
+  def : Property<"sugared", Bool> {
+    let Read = [{ parm->getFinal() }];
+  }
   def : Creator<[{
-    return ctx.getSubstTemplateTemplateParmPack(argumentPack, associatedDecl, index);
+    return ctx.getSubstTemplateTemplateParmPack(argumentPack, associatedDecl, index, sugared);
   }]>;
 }
 
diff --git a/clang/include/clang/AST/TemplateName.h b/clang/include/clang/AST/TemplateName.h
--- a/clang/include/clang/AST/TemplateName.h
+++ b/clang/include/clang/AST/TemplateName.h
@@ -139,25 +139,24 @@
 class SubstTemplateTemplateParmPackStorage : public UncommonTemplateNameStorage,
                                              public llvm::FoldingSetNode {
   const TemplateArgument *Arguments;
-  Decl *AssociatedDecl;
+  llvm::PointerIntPair<Decl *, 1, bool> AssociatedDeclAndFinal;
 
 public:
   SubstTemplateTemplateParmPackStorage(ArrayRef<TemplateArgument> ArgPack,
-                                       Decl *AssociatedDecl, unsigned Index)
-      : UncommonTemplateNameStorage(SubstTemplateTemplateParmPack, Index,
-                                    ArgPack.size()),
-        Arguments(ArgPack.data()), AssociatedDecl(AssociatedDecl) {
-    assert(AssociatedDecl != nullptr);
-  }
+                                       Decl *AssociatedDecl, unsigned Index,
+                                       bool Final);
 
   /// A template-like entity which owns the whole pattern being substituted.
   /// This will own a set of template parameters.
-  Decl *getAssociatedDecl() const { return AssociatedDecl; }
+  Decl *getAssociatedDecl() const;
 
   /// Returns the index of the replaced parameter in the associated declaration.
   /// This should match the result of `getParameterPack()->getIndex()`.
   unsigned getIndex() const { return Bits.Index; }
 
+  // When true the substitution will be finalized (subst node won't be placed).
+  bool getFinal() const;
+
   /// Retrieve the template template parameter pack being substituted.
   TemplateTemplateParmDecl *getParameterPack() const;
 
@@ -169,7 +168,7 @@
 
   static void Profile(llvm::FoldingSetNodeID &ID, ASTContext &Context,
                       const TemplateArgument &ArgPack, Decl *AssociatedDecl,
-                      unsigned Index);
+                      unsigned Index, bool Final);
 };
 
 /// Represents a C++ template name within the type system.
diff --git a/clang/include/clang/AST/Type.h b/clang/include/clang/AST/Type.h
--- a/clang/include/clang/AST/Type.h
+++ b/clang/include/clang/AST/Type.h
@@ -5156,10 +5156,10 @@
   /// parameter pack is instantiated with.
   const TemplateArgument *Arguments;
 
-  Decl *AssociatedDecl;
+  llvm::PointerIntPair<Decl *, 1, bool> AssociatedDeclAndFinal;
 
   SubstTemplateTypeParmPackType(QualType Canon, Decl *AssociatedDecl,
-                                unsigned Index,
+                                unsigned Index, bool Final,
                                 const TemplateArgument &ArgPack);
 
 public:
@@ -5168,7 +5168,7 @@
   /// A template-like entity which owns the whole pattern being substituted.
   /// This will usually own a set of template parameters, or in some
   /// cases might even be a template parameter itself.
-  Decl *getAssociatedDecl() const { return AssociatedDecl; }
+  Decl *getAssociatedDecl() const;
 
   /// Gets the template parameter declaration that was substituted for.
   const TemplateTypeParmDecl *getReplacedParameter() const;
@@ -5177,6 +5177,9 @@
   /// This should match the result of `getReplacedParameter()->getIndex()`.
   unsigned getIndex() const { return SubstTemplateTypeParmPackTypeBits.Index; }
 
+  // When true the substitution will be finalized (subst node won't be placed).
+  bool getFinal() const;
+
   unsigned getNumArgs() const {
     return SubstTemplateTypeParmPackTypeBits.NumArgs;
   }
@@ -5188,7 +5191,8 @@
 
   void Profile(llvm::FoldingSetNodeID &ID);
   static void Profile(llvm::FoldingSetNodeID &ID, const Decl *AssociatedDecl,
-                      unsigned Index, const TemplateArgument &ArgPack);
+                      unsigned Index, bool Final,
+                      const TemplateArgument &ArgPack);
 
   static bool classof(const Type *T) {
     return T->getTypeClass() == SubstTemplateTypeParmPack;
diff --git a/clang/include/clang/AST/TypeProperties.td b/clang/include/clang/AST/TypeProperties.td
--- a/clang/include/clang/AST/TypeProperties.td
+++ b/clang/include/clang/AST/TypeProperties.td
@@ -773,13 +773,16 @@
   def : Property<"Index", UInt32> {
     let Read = [{ node->getIndex() }];
   }
+  def : Property<"Final", Bool> {
+    let Read = [{ node->getFinal() }];
+  }
   def : Property<"replacementPack", TemplateArgument> {
     let Read = [{ node->getArgumentPack() }];
   }
 
   def : Creator<[{
     return ctx.getSubstTemplateTypeParmPackType(
-                        associatedDecl, Index, replacementPack);
+                        associatedDecl, Index, Final, replacementPack);
   }]>;
 }
 
diff --git a/clang/include/clang/Sema/Sema.h b/clang/include/clang/Sema/Sema.h
--- a/clang/include/clang/Sema/Sema.h
+++ b/clang/include/clang/Sema/Sema.h
@@ -9078,10 +9078,12 @@
   // C++ Template Instantiation
   //
 
-  MultiLevelTemplateArgumentList getTemplateInstantiationArgs(
-      const NamedDecl *D, const TemplateArgumentList *Innermost = nullptr,
-      bool RelativeToPrimary = false, const FunctionDecl *Pattern = nullptr,
-      bool ForConstraintInstantiation = false);
+  MultiLevelTemplateArgumentList
+  getTemplateInstantiationArgs(const NamedDecl *D, bool Final = false,
+                               const TemplateArgumentList *Innermost = nullptr,
+                               bool RelativeToPrimary = false,
+                               const FunctionDecl *Pattern = nullptr,
+                               bool ForConstraintInstantiation = false);
 
   /// A context in which code is being synthesized (where a source location
   /// alone is not sufficient to identify the context). This covers template
@@ -10175,16 +10177,12 @@
                                   bool FailOnError = false);
 
   /// Build an Objective-C object pointer type.
-  QualType BuildObjCObjectType(QualType BaseType,
-                               SourceLocation Loc,
-                               SourceLocation TypeArgsLAngleLoc,
-                               ArrayRef<TypeSourceInfo *> TypeArgs,
-                               SourceLocation TypeArgsRAngleLoc,
-                               SourceLocation ProtocolLAngleLoc,
-                               ArrayRef<ObjCProtocolDecl *> Protocols,
-                               ArrayRef<SourceLocation> ProtocolLocs,
-                               SourceLocation ProtocolRAngleLoc,
-                               bool FailOnError = false);
+  QualType BuildObjCObjectType(
+      QualType BaseType, SourceLocation Loc, SourceLocation TypeArgsLAngleLoc,
+      ArrayRef<TypeSourceInfo *> TypeArgs, SourceLocation TypeArgsRAngleLoc,
+      SourceLocation ProtocolLAngleLoc, ArrayRef<ObjCProtocolDecl *> Protocols,
+      ArrayRef<SourceLocation> ProtocolLocs, SourceLocation ProtocolRAngleLoc,
+      bool FailOnError, bool Rebuilding);
 
   /// Ensure attributes are consistent with type.
   /// \param [in, out] Attributes The attributes to check; they will
diff --git a/clang/include/clang/Sema/Template.h b/clang/include/clang/Sema/Template.h
--- a/clang/include/clang/Sema/Template.h
+++ b/clang/include/clang/Sema/Template.h
@@ -77,7 +77,7 @@
 
     using ArgList = ArrayRef<TemplateArgument>;
     struct ArgumentListLevel {
-      Decl *AssociatedDecl;
+      llvm::PointerIntPair<Decl *, 1, bool> AssociatedDeclAsFinal;
       ArgList Args;
     };
     using ContainerType = SmallVector<ArgumentListLevel, 4>;
@@ -101,8 +101,8 @@
     MultiLevelTemplateArgumentList() = default;
 
     /// Construct a single-level template argument list.
-    MultiLevelTemplateArgumentList(Decl *D, ArgList Args) {
-      addOuterTemplateArguments(D, Args);
+    MultiLevelTemplateArgumentList(Decl *D, ArgList Args, bool Final) {
+      addOuterTemplateArguments(D, Args, Final);
     }
 
     void setKind(TemplateSubstitutionKind K) { Kind = K; }
@@ -160,9 +160,12 @@
     /// A template-like entity which owns the whole pattern being substituted.
     /// This will usually own a set of template parameters, or in some
     /// cases might even be a template parameter itself.
-    Decl *getAssociatedDecl(unsigned Depth) const {
+    /// Returns nullptr for fully-sugared substitutions.
+    std::pair<Decl *, bool> getAssociatedDecl(unsigned Depth) const {
       assert(NumRetainedOuterLevels <= Depth && Depth < getNumLevels());
-      return TemplateArgumentLists[getNumLevels() - Depth - 1].AssociatedDecl;
+      auto AD = TemplateArgumentLists[getNumLevels() - Depth - 1]
+                    .AssociatedDeclAsFinal;
+      return {AD.getPointer(), AD.getInt()};
     }
 
     /// Determine whether there is a non-NULL template argument at the
@@ -202,21 +205,22 @@
 
     /// Add a new outmost level to the multi-level template argument
     /// list.
-    void addOuterTemplateArguments(Decl *AssociatedDecl, ArgList Args) {
+    /// A 'Final' substitution means that Subst* nodes won't be built
+    /// for the replacements.
+    void addOuterTemplateArguments(Decl *AssociatedDecl, ArgList Args,
+                                   bool Final) {
       assert(!NumRetainedOuterLevels &&
              "substituted args outside retained args?");
       assert(getKind() == TemplateSubstitutionKind::Specialization);
-      assert(AssociatedDecl != nullptr || Args.size() == 0);
       TemplateArgumentLists.push_back(
-          {AssociatedDecl ? AssociatedDecl->getCanonicalDecl() : nullptr,
-           Args});
+          {{AssociatedDecl->getCanonicalDecl(), Final}, Args});
     }
 
     void addOuterTemplateArguments(ArgList Args) {
       assert(!NumRetainedOuterLevels &&
              "substituted args outside retained args?");
       assert(getKind() == TemplateSubstitutionKind::Rewrite);
-      TemplateArgumentLists.push_back({nullptr, Args});
+      TemplateArgumentLists.push_back({{}, Args});
     }
 
     void addOuterTemplateArguments(llvm::NoneType) {
diff --git a/clang/lib/AST/ASTContext.cpp b/clang/lib/AST/ASTContext.cpp
--- a/clang/lib/AST/ASTContext.cpp
+++ b/clang/lib/AST/ASTContext.cpp
@@ -3041,6 +3041,23 @@
   return getObjCLayout(D->getClassInterface(), D);
 }
 
+static bool
+getCanonicalTemplateArguments(const ASTContext &C,
+                              ArrayRef<TemplateArgument> OrigArgs,
+                              SmallVectorImpl<TemplateArgument> &CanonArgs) {
+  bool AnyNonCanonArgs = false;
+  unsigned NumArgs = OrigArgs.size();
+  CanonArgs.resize(NumArgs);
+  for (unsigned I = 0; I != NumArgs; ++I) {
+    const TemplateArgument &OrigArg = OrigArgs[I];
+    TemplateArgument &CanonArg = CanonArgs[I];
+    CanonArg = C.getCanonicalTemplateArgument(OrigArg);
+    if (!CanonArg.structurallyEquals(OrigArg))
+      AnyNonCanonArgs = true;
+  }
+  return AnyNonCanonArgs;
+}
+
 //===----------------------------------------------------------------------===//
 //                   Type creation/memoization methods
 //===----------------------------------------------------------------------===//
@@ -4848,31 +4865,42 @@
 }
 
 /// Retrieve a
-QualType ASTContext::getSubstTemplateTypeParmPackType(
-    Decl *AssociatedDecl, unsigned Index, const TemplateArgument &ArgPack) {
+QualType
+ASTContext::getSubstTemplateTypeParmPackType(Decl *AssociatedDecl,
+                                             unsigned Index, bool Final,
+                                             const TemplateArgument &ArgPack) {
 #ifndef NDEBUG
-  for (const auto &P : ArgPack.pack_elements()) {
+  for (const auto &P : ArgPack.pack_elements())
     assert(P.getKind() == TemplateArgument::Type && "Pack contains a non-type");
-    assert(P.getAsType().isCanonical() && "Pack contains non-canonical type");
-  }
 #endif
 
   llvm::FoldingSetNodeID ID;
-  SubstTemplateTypeParmPackType::Profile(ID, AssociatedDecl, Index, ArgPack);
+  SubstTemplateTypeParmPackType::Profile(ID, AssociatedDecl, Index, Final,
+                                         ArgPack);
   void *InsertPos = nullptr;
   if (SubstTemplateTypeParmPackType *SubstParm =
           SubstTemplateTypeParmPackTypes.FindNodeOrInsertPos(ID, InsertPos))
     return QualType(SubstParm, 0);
 
   QualType Canon;
-  if (!AssociatedDecl->isCanonicalDecl()) {
-    Canon = getSubstTemplateTypeParmPackType(AssociatedDecl->getCanonicalDecl(),
-                                             Index, ArgPack);
-    SubstTemplateTypeParmPackTypes.FindNodeOrInsertPos(ID, InsertPos);
-  }
-
-  auto *SubstParm = new (*this, TypeAlignment)
-      SubstTemplateTypeParmPackType(Canon, AssociatedDecl, Index, ArgPack);
+  {
+    SmallVector<TemplateArgument, 8> Args(ArgPack.pack_size());
+    TemplateArgument CanonArgPack = ArgPack;
+    bool AnyNonCanonArgs =
+        getCanonicalTemplateArguments(*this, ArgPack.pack_elements(), Args);
+    if (AnyNonCanonArgs)
+      CanonArgPack = TemplateArgument::CreatePackCopy(*this, Args);
+    if (!AssociatedDecl->isCanonicalDecl() || AnyNonCanonArgs) {
+      Canon = getSubstTemplateTypeParmPackType(
+          AssociatedDecl->getCanonicalDecl(), Index, Final, CanonArgPack);
+      [[maybe_unused]] const auto *Nothing =
+          SubstTemplateTypeParmPackTypes.FindNodeOrInsertPos(ID, InsertPos);
+      assert(!Nothing);
+    }
+  }
+
+  auto *SubstParm = new (*this, TypeAlignment) SubstTemplateTypeParmPackType(
+      Canon, AssociatedDecl, Index, Final, ArgPack);
   Types.push_back(SubstParm);
   SubstTemplateTypeParmPackTypes.InsertNode(SubstParm, InsertPos);
   return QualType(SubstParm, 0);
@@ -4997,23 +5025,6 @@
   return QualType(Spec, 0);
 }
 
-static bool
-getCanonicalTemplateArguments(const ASTContext &C,
-                              ArrayRef<TemplateArgument> OrigArgs,
-                              SmallVectorImpl<TemplateArgument> &CanonArgs) {
-  bool AnyNonCanonArgs = false;
-  unsigned NumArgs = OrigArgs.size();
-  CanonArgs.resize(NumArgs);
-  for (unsigned I = 0; I != NumArgs; ++I) {
-    const TemplateArgument &OrigArg = OrigArgs[I];
-    TemplateArgument &CanonArg = CanonArgs[I];
-    CanonArg = C.getCanonicalTemplateArgument(OrigArg);
-    if (!CanonArg.structurallyEquals(OrigArg))
-      AnyNonCanonArgs = true;
-  }
-  return AnyNonCanonArgs;
-}
-
 QualType ASTContext::getCanonicalTemplateSpecializationType(
     TemplateName Template, ArrayRef<TemplateArgument> Args) const {
   assert(!Template.getAsDependentTemplateName() &&
@@ -6284,7 +6295,7 @@
         getCanonicalTemplateArgument(subst->getArgumentPack());
     return getSubstTemplateTemplateParmPack(
         canonArgPack, subst->getAssociatedDecl()->getCanonicalDecl(),
-        subst->getIndex());
+        subst->getFinal(), subst->getIndex());
   }
   }
 
@@ -9310,11 +9321,11 @@
 TemplateName
 ASTContext::getSubstTemplateTemplateParmPack(const TemplateArgument &ArgPack,
                                              Decl *AssociatedDecl,
-                                             unsigned Index) const {
+                                             unsigned Index, bool Final) const {
   auto &Self = const_cast<ASTContext &>(*this);
   llvm::FoldingSetNodeID ID;
   SubstTemplateTemplateParmPackStorage::Profile(ID, Self, ArgPack,
-                                                AssociatedDecl, Index);
+                                                AssociatedDecl, Index, Final);
 
   void *InsertPos = nullptr;
   SubstTemplateTemplateParmPackStorage *Subst
@@ -9322,7 +9333,7 @@
 
   if (!Subst) {
     Subst = new (*this) SubstTemplateTemplateParmPackStorage(
-        ArgPack.pack_elements(), AssociatedDecl, Index);
+        ArgPack.pack_elements(), AssociatedDecl, Index, Final);
     SubstTemplateTemplateParmPacks.InsertNode(Subst, InsertPos);
   }
 
diff --git a/clang/lib/AST/ASTImporter.cpp b/clang/lib/AST/ASTImporter.cpp
--- a/clang/lib/AST/ASTImporter.cpp
+++ b/clang/lib/AST/ASTImporter.cpp
@@ -1547,7 +1547,7 @@
     return ToArgumentPack.takeError();
 
   return Importer.getToContext().getSubstTemplateTypeParmPackType(
-      *ReplacedOrErr, T->getIndex(), *ToArgumentPack);
+      *ReplacedOrErr, T->getIndex(), T->getFinal(), *ToArgumentPack);
 }
 
 ExpectedType ASTNodeImporter::VisitTemplateSpecializationType(
@@ -9447,7 +9447,8 @@
       return AssociatedDeclOrErr.takeError();
 
     return ToContext.getSubstTemplateTemplateParmPack(
-        *ArgPackOrErr, *AssociatedDeclOrErr, SubstPack->getIndex());
+        *ArgPackOrErr, *AssociatedDeclOrErr, SubstPack->getIndex(),
+        SubstPack->getFinal());
   }
   case TemplateName::UsingTemplate: {
     auto UsingOrError = Import(From.getAsUsingShadowDecl());
diff --git a/clang/lib/AST/TemplateName.cpp b/clang/lib/AST/TemplateName.cpp
--- a/clang/lib/AST/TemplateName.cpp
+++ b/clang/lib/AST/TemplateName.cpp
@@ -67,17 +67,37 @@
   ID.AddInteger(PackIndex ? *PackIndex + 1 : 0);
 }
 
+SubstTemplateTemplateParmPackStorage::SubstTemplateTemplateParmPackStorage(
+    ArrayRef<TemplateArgument> ArgPack, Decl *AssociatedDecl, unsigned Index,
+    bool Final)
+    : UncommonTemplateNameStorage(SubstTemplateTemplateParmPack, Index,
+                                  ArgPack.size()),
+      Arguments(ArgPack.data()), AssociatedDeclAndFinal(AssociatedDecl, Final) {
+  assert(AssociatedDecl != nullptr);
+}
+
 void SubstTemplateTemplateParmPackStorage::Profile(llvm::FoldingSetNodeID &ID,
                                                    ASTContext &Context) {
-  Profile(ID, Context, getArgumentPack(), getAssociatedDecl(), getIndex());
+  Profile(ID, Context, getArgumentPack(), getAssociatedDecl(), getIndex(),
+          getFinal());
+}
+
+Decl *SubstTemplateTemplateParmPackStorage::getAssociatedDecl() const {
+  return AssociatedDeclAndFinal.getPointer();
+}
+
+bool SubstTemplateTemplateParmPackStorage::getFinal() const {
+  return AssociatedDeclAndFinal.getInt();
 }
 
 void SubstTemplateTemplateParmPackStorage::Profile(
     llvm::FoldingSetNodeID &ID, ASTContext &Context,
-    const TemplateArgument &ArgPack, Decl *AssociatedDecl, unsigned Index) {
+    const TemplateArgument &ArgPack, Decl *AssociatedDecl, unsigned Index,
+    bool Final) {
   ArgPack.Profile(ID, Context);
   ID.AddPointer(AssociatedDecl);
   ID.AddInteger(Index);
+  ID.AddBoolean(Final);
 }
 
 TemplateName::TemplateName(void *Ptr) {
diff --git a/clang/lib/AST/Type.cpp b/clang/lib/AST/Type.cpp
--- a/clang/lib/AST/Type.cpp
+++ b/clang/lib/AST/Type.cpp
@@ -3666,17 +3666,26 @@
 }
 
 SubstTemplateTypeParmPackType::SubstTemplateTypeParmPackType(
-    QualType Canon, Decl *AssociatedDecl, unsigned Index,
+    QualType Canon, Decl *AssociatedDecl, unsigned Index, bool Final,
     const TemplateArgument &ArgPack)
     : Type(SubstTemplateTypeParmPack, Canon,
            TypeDependence::DependentInstantiation |
                TypeDependence::UnexpandedPack),
-      Arguments(ArgPack.pack_begin()), AssociatedDecl(AssociatedDecl) {
+      Arguments(ArgPack.pack_begin()),
+      AssociatedDeclAndFinal(AssociatedDecl, Final) {
   SubstTemplateTypeParmPackTypeBits.Index = Index;
   SubstTemplateTypeParmPackTypeBits.NumArgs = ArgPack.pack_size();
   assert(AssociatedDecl != nullptr);
 }
 
+Decl *SubstTemplateTypeParmPackType::getAssociatedDecl() const {
+  return AssociatedDeclAndFinal.getPointer();
+}
+
+bool SubstTemplateTypeParmPackType::getFinal() const {
+  return AssociatedDeclAndFinal.getInt();
+}
+
 const TemplateTypeParmDecl *
 SubstTemplateTypeParmPackType::getReplacedParameter() const {
   return ::getReplacedParameter(getAssociatedDecl(), getIndex());
@@ -3691,15 +3700,16 @@
 }
 
 void SubstTemplateTypeParmPackType::Profile(llvm::FoldingSetNodeID &ID) {
-  Profile(ID, getAssociatedDecl(), getIndex(), getArgumentPack());
+  Profile(ID, getAssociatedDecl(), getIndex(), getFinal(), getArgumentPack());
 }
 
 void SubstTemplateTypeParmPackType::Profile(llvm::FoldingSetNodeID &ID,
                                             const Decl *AssociatedDecl,
-                                            unsigned Index,
+                                            unsigned Index, bool Final,
                                             const TemplateArgument &ArgPack) {
   ID.AddPointer(AssociatedDecl);
   ID.AddInteger(Index);
+  ID.AddBoolean(Final);
   ID.AddInteger(ArgPack.pack_size());
   for (const auto &P : ArgPack.pack_elements())
     ID.AddPointer(P.getAsType().getAsOpaquePtr());
diff --git a/clang/lib/Sema/SemaConcept.cpp b/clang/lib/Sema/SemaConcept.cpp
--- a/clang/lib/Sema/SemaConcept.cpp
+++ b/clang/lib/Sema/SemaConcept.cpp
@@ -453,7 +453,8 @@
     // the list of current template arguments to the list so that they also can
     // be picked out of the map.
     if (auto *SpecArgs = FD->getTemplateSpecializationArgs()) {
-      MultiLevelTemplateArgumentList JustTemplArgs(FD, SpecArgs->asArray());
+      MultiLevelTemplateArgumentList JustTemplArgs(FD, SpecArgs->asArray(),
+                                                   /*Final=*/false);
       if (addInstantiatedParametersToScope(
               FD, PrimaryTemplate->getTemplatedDecl(), Scope, JustTemplArgs))
         return true;
@@ -506,10 +507,11 @@
   // Collect the list of template arguments relative to the 'primary' template.
   // We need the entire list, since the constraint is completely uninstantiated
   // at this point.
-  MLTAL = getTemplateInstantiationArgs(FD, /*Innermost=*/nullptr,
-                                       /*RelativeToPrimary=*/true,
-                                       /*Pattern=*/nullptr,
-                                       /*ForConstraintInstantiation=*/true);
+  MLTAL =
+      getTemplateInstantiationArgs(FD, /*Final=*/false, /*Innermost=*/nullptr,
+                                   /*RelativeToPrimary=*/true,
+                                   /*Pattern=*/nullptr,
+                                   /*ForConstraintInstantiation=*/true);
   if (SetupConstraintScope(FD, TemplateArgs, MLTAL, Scope))
     return llvm::None;
 
@@ -586,7 +588,7 @@
 static unsigned CalculateTemplateDepthForConstraints(Sema &S,
                                                      const NamedDecl *ND) {
   MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
-      ND, /*Innermost=*/nullptr, /*RelativeToPrimary=*/true,
+      ND, /*Final=*/false, /*Innermost=*/nullptr, /*RelativeToPrimary=*/true,
       /*Pattern=*/nullptr,
       /*ForConstraintInstantiation=*/true);
   return MLTAL.getNumSubstitutedLevels();
@@ -599,8 +601,10 @@
   using inherited = TreeTransform<AdjustConstraintDepth>;
   AdjustConstraintDepth(Sema &SemaRef, unsigned TemplateDepth)
       : inherited(SemaRef), TemplateDepth(TemplateDepth) {}
+
+  using inherited::TransformTemplateTypeParmType;
   QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
-                                         TemplateTypeParmTypeLoc TL) {
+                                         TemplateTypeParmTypeLoc TL, bool) {
     const TemplateTypeParmType *T = TL.getTypePtr();
 
     TemplateTypeParmDecl *NewTTPDecl = nullptr;
@@ -1071,11 +1075,11 @@
                                         const ConceptSpecializationExpr *CSE) {
   TemplateArgumentList TAL{TemplateArgumentList::OnStack,
                            CSE->getTemplateArguments()};
-  MultiLevelTemplateArgumentList MLTAL =
-      S.getTemplateInstantiationArgs(CSE->getNamedConcept(), &TAL,
-                                     /*RelativeToPrimary=*/true,
-                                     /*Pattern=*/nullptr,
-                                     /*ForConstraintInstantiation=*/true);
+  MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
+      CSE->getNamedConcept(), /*Final=*/false, &TAL,
+      /*RelativeToPrimary=*/true,
+      /*Pattern=*/nullptr,
+      /*ForConstraintInstantiation=*/true);
 
   return substituteParameterMappings(S, N, CSE->getNamedConcept(), MLTAL,
                                      CSE->getTemplateArgsAsWritten());
diff --git a/clang/lib/Sema/SemaExprCXX.cpp b/clang/lib/Sema/SemaExprCXX.cpp
--- a/clang/lib/Sema/SemaExprCXX.cpp
+++ b/clang/lib/Sema/SemaExprCXX.cpp
@@ -8964,7 +8964,8 @@
     auto *Param = cast<TemplateTypeParmDecl>(TPL->getParam(0));
 
     TemplateArgumentList TAL(TemplateArgumentList::OnStack, Args);
-    MultiLevelTemplateArgumentList MLTAL(Param, TAL.asArray());
+    MultiLevelTemplateArgumentList MLTAL(Param, TAL.asArray(),
+                                         /*Final=*/false);
     MLTAL.addOuterRetainedLevels(TPL->getDepth());
     Expr *IDC = Param->getTypeConstraint()->getImmediatelyDeclaredConstraint();
     ExprResult Constraint = SubstExpr(IDC, MLTAL);
diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
--- a/clang/lib/Sema/SemaTemplate.cpp
+++ b/clang/lib/Sema/SemaTemplate.cpp
@@ -1720,14 +1720,17 @@
   // SubstTempalteTypeParmPack, SubstNonTypeTemplateParmPack, and
   // FunctionParmPackExpr are all partially substituted, which cannot happen
   // with concepts at this point in translation.
+  using inherited::TransformTemplateTypeParmType;
   QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
-                                         TemplateTypeParmTypeLoc TL) {
+                                         TemplateTypeParmTypeLoc TL, bool) {
     assert(TL.getDecl()->getDepth() <= TemplateDepth &&
            "Nothing should reference a value below the actual template depth, "
            "depth is likely wrong");
     if (TL.getDecl()->getDepth() != TemplateDepth)
       Result = true;
-    return inherited::TransformTemplateTypeParmType(TLB, TL);
+    return inherited::TransformTemplateTypeParmType(
+        TLB, TL,
+        /*SuppressObjCLifetime=*/false);
   }
 
   Decl *TransformDecl(SourceLocation Loc, Decl *D) {
@@ -3850,13 +3853,10 @@
     if (Pattern->isInvalidDecl())
       return QualType();
 
-    TemplateArgumentList StackTemplateArgs(TemplateArgumentList::OnStack,
-                                           CanonicalConverted);
-
     // Only substitute for the innermost template argument list.
     MultiLevelTemplateArgumentList TemplateArgLists;
-    TemplateArgLists.addOuterTemplateArguments(Template,
-                                               StackTemplateArgs.asArray());
+    TemplateArgLists.addOuterTemplateArguments(Template, CanonicalConverted,
+                                               /*Final=*/false);
     TemplateArgLists.addOuterRetainedLevels(
         AliasTemplate->getTemplateParameters()->getDepth());
 
@@ -3982,9 +3982,9 @@
         ClassTemplate->getTemplatedDecl()->hasAttrs()) {
       InstantiatingTemplate Inst(*this, TemplateLoc, Decl);
       if (!Inst.isInvalid()) {
-        MultiLevelTemplateArgumentList TemplateArgLists;
-        TemplateArgLists.addOuterTemplateArguments(Template,
-                                                   CanonicalConverted);
+        MultiLevelTemplateArgumentList TemplateArgLists(Template,
+                                                        CanonicalConverted,
+                                                        /*Final=*/false);
         InstantiateAttrsForDecl(TemplateArgLists,
                                 ClassTemplate->getTemplatedDecl(), Decl);
       }
@@ -4865,7 +4865,8 @@
   bool AreArgsDependent =
       TemplateSpecializationType::anyDependentTemplateArguments(
           *TemplateArgs, CanonicalConverted);
-  MultiLevelTemplateArgumentList MLTAL(NamedConcept, CanonicalConverted);
+  MultiLevelTemplateArgumentList MLTAL(NamedConcept, CanonicalConverted,
+                                       /*Final=*/false);
   LocalInstantiationScope Scope(*this);
   if (!AreArgsDependent &&
       CheckConstraintSatisfaction(
@@ -5273,11 +5274,9 @@
     if (Inst.isInvalid())
       return nullptr;
 
-    TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
-
     // Only substitute for the innermost template argument list.
-    MultiLevelTemplateArgumentList TemplateArgLists(Template,
-                                                    TemplateArgs.asArray());
+    MultiLevelTemplateArgumentList TemplateArgLists(Template, Converted,
+                                                    /*Final=*/false);
     for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
       TemplateArgLists.addOuterTemplateArguments(None);
 
@@ -5329,11 +5328,9 @@
   if (Inst.isInvalid())
     return ExprError();
 
-  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
-
   // Only substitute for the innermost template argument list.
-  MultiLevelTemplateArgumentList TemplateArgLists(Template,
-                                                  TemplateArgs.asArray());
+  MultiLevelTemplateArgumentList TemplateArgLists(Template, Converted,
+                                                  /*Final=*/false);
   for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
     TemplateArgLists.addOuterTemplateArguments(None);
 
@@ -5382,11 +5379,9 @@
   if (Inst.isInvalid())
     return TemplateName();
 
-  TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack, Converted);
-
   // Only substitute for the innermost template argument list.
-  MultiLevelTemplateArgumentList TemplateArgLists(Template,
-                                                  TemplateArgs.asArray());
+  MultiLevelTemplateArgumentList TemplateArgLists(Template, Converted,
+                                                  /*Final=*/false);
   for (unsigned i = 0, e = Param->getDepth(); i != e; ++i)
     TemplateArgLists.addOuterTemplateArguments(None);
 
@@ -5567,10 +5562,8 @@
       if (Inst.isInvalid())
         return true;
 
-      TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
-                                        CanonicalConverted);
-
-      MultiLevelTemplateArgumentList MLTAL(Template, TemplateArgs.asArray());
+      MultiLevelTemplateArgumentList MLTAL(Template, CanonicalConverted,
+                                           /*Final=*/false);
       // If the parameter is a pack expansion, expand this slice of the pack.
       if (auto *PET = NTTPType->getAs<PackExpansionType>()) {
         Sema::ArgumentPackSubstitutionIndexRAII SubstIndex(*this,
@@ -5732,9 +5725,10 @@
     if (Inst.isInvalid())
       return true;
 
-    Params = SubstTemplateParams(
-        Params, CurContext,
-        MultiLevelTemplateArgumentList(Template, CanonicalConverted));
+    Params =
+        SubstTemplateParams(Params, CurContext,
+                            MultiLevelTemplateArgumentList(
+                                Template, CanonicalConverted, /*Final=*/false));
     if (!Params)
       return true;
   }
@@ -6133,7 +6127,8 @@
     CXXThisScopeRAII(*this, RD, ThisQuals, RD != nullptr);
 
     MultiLevelTemplateArgumentList MLTAL = getTemplateInstantiationArgs(
-        Template, &StackTemplateArgs, /*RelativeToPrimary=*/true,
+        Template, /*Final=*/false, &StackTemplateArgs,
+        /*RelativeToPrimary=*/true,
         /*Pattern=*/nullptr,
         /*ForConceptInstantiation=*/true);
     if (EnsureTemplateArgumentListConstraints(
diff --git a/clang/lib/Sema/SemaTemplateDeduction.cpp b/clang/lib/Sema/SemaTemplateDeduction.cpp
--- a/clang/lib/Sema/SemaTemplateDeduction.cpp
+++ b/clang/lib/Sema/SemaTemplateDeduction.cpp
@@ -2687,9 +2687,8 @@
     // itself, in case that substitution fails.
     if (SugaredPackedArgsBuilder.empty()) {
       LocalInstantiationScope Scope(S);
-      TemplateArgumentList TemplateArgs(TemplateArgumentList::OnStack,
-                                        CanonicalOutput);
-      MultiLevelTemplateArgumentList Args(Template, TemplateArgs.asArray());
+      MultiLevelTemplateArgumentList Args(Template, CanonicalOutput,
+                                          /*Final=*/false);
 
       if (auto *NTTP = dyn_cast<NonTypeTemplateParmDecl>(Param)) {
         Sema::InstantiatingTemplate Inst(S, Template->getLocation(), Template,
@@ -2890,7 +2889,8 @@
                                   CanonicalDeducedArgs};
 
   MultiLevelTemplateArgumentList MLTAL = S.getTemplateInstantiationArgs(
-      Template, /*InnerMost=*/NeedsReplacement ? nullptr : &DeducedTAL,
+      Template, /*Final=*/false,
+      /*InnerMost=*/NeedsReplacement ? nullptr : &DeducedTAL,
       /*RelativeToPrimary=*/true, /*Pattern=*/
       nullptr, /*ForConstraintInstantiation=*/true);
 
@@ -2959,11 +2959,12 @@
   TemplateArgumentListInfo InstArgs(PartialTemplArgInfo->LAngleLoc,
                                     PartialTemplArgInfo->RAngleLoc);
 
-  if (S.SubstTemplateArguments(
-          PartialTemplArgInfo->arguments(),
-          MultiLevelTemplateArgumentList(
-              Partial, CanonicalDeducedArgumentList->asArray()),
-          InstArgs)) {
+  if (S.SubstTemplateArguments(PartialTemplArgInfo->arguments(),
+                               MultiLevelTemplateArgumentList(
+                                   Partial,
+                                   CanonicalDeducedArgumentList->asArray(),
+                                   /*Final=*/false),
+                               InstArgs)) {
     unsigned ArgIdx = InstArgs.size(), ParamIdx = ArgIdx;
     if (ParamIdx >= Partial->getTemplateParameters()->size())
       ParamIdx = Partial->getTemplateParameters()->size() - 1;
@@ -3301,17 +3302,18 @@
 
   ExtParameterInfoBuilder ExtParamInfos;
 
+  MultiLevelTemplateArgumentList MLTAL(FunctionTemplate,
+                                       CanonicalExplicitArgumentList->asArray(),
+                                       /*Final=*/false);
+
   // Instantiate the types of each of the function parameters given the
   // explicitly-specified template arguments. If the function has a trailing
   // return type, substitute it after the arguments to ensure we substitute
   // in lexical order.
   if (Proto->hasTrailingReturn()) {
-    if (SubstParmTypes(
-            Function->getLocation(), Function->parameters(),
-            Proto->getExtParameterInfosOrNull(),
-            MultiLevelTemplateArgumentList(
-                FunctionTemplate, CanonicalExplicitArgumentList->asArray()),
-            ParamTypes, /*params=*/nullptr, ExtParamInfos))
+    if (SubstParmTypes(Function->getLocation(), Function->parameters(),
+                       Proto->getExtParameterInfosOrNull(), MLTAL, ParamTypes,
+                       /*params=*/nullptr, ExtParamInfos))
       return TDK_SubstitutionFailure;
   }
 
@@ -3334,11 +3336,9 @@
     CXXThisScopeRAII ThisScope(*this, ThisContext, ThisTypeQuals,
                                getLangOpts().CPlusPlus11);
 
-    ResultType = SubstType(
-        Proto->getReturnType(),
-        MultiLevelTemplateArgumentList(
-            FunctionTemplate, CanonicalExplicitArgumentList->asArray()),
-        Function->getTypeSpecStartLoc(), Function->getDeclName());
+    ResultType =
+        SubstType(Proto->getReturnType(), MLTAL,
+                  Function->getTypeSpecStartLoc(), Function->getDeclName());
     if (ResultType.isNull() || Trap.hasErrorOccurred())
       return TDK_SubstitutionFailure;
     // CUDA: Kernel function must have 'void' return type.
@@ -3353,12 +3353,9 @@
   // Instantiate the types of each of the function parameters given the
   // explicitly-specified template arguments if we didn't do so earlier.
   if (!Proto->hasTrailingReturn() &&
-      SubstParmTypes(
-          Function->getLocation(), Function->parameters(),
-          Proto->getExtParameterInfosOrNull(),
-          MultiLevelTemplateArgumentList(
-              FunctionTemplate, CanonicalExplicitArgumentList->asArray()),
-          ParamTypes, /*params*/ nullptr, ExtParamInfos))
+      SubstParmTypes(Function->getLocation(), Function->parameters(),
+                     Proto->getExtParameterInfosOrNull(), MLTAL, ParamTypes,
+                     /*params*/ nullptr, ExtParamInfos))
     return TDK_SubstitutionFailure;
 
   if (FunctionType) {
@@ -3370,10 +3367,8 @@
     // specification.
     SmallVector<QualType, 4> ExceptionStorage;
     if (getLangOpts().CPlusPlus17 &&
-        SubstExceptionSpec(
-            Function->getLocation(), EPI.ExceptionSpec, ExceptionStorage,
-            MultiLevelTemplateArgumentList(
-                FunctionTemplate, CanonicalExplicitArgumentList->asArray())))
+        SubstExceptionSpec(Function->getLocation(), EPI.ExceptionSpec,
+                           ExceptionStorage, MLTAL))
       return TDK_SubstitutionFailure;
 
     *FunctionType = BuildFunctionType(ResultType, ParamTypes,
@@ -3616,7 +3611,8 @@
   if (FunctionTemplate->getFriendObjectKind())
     Owner = FunctionTemplate->getLexicalDeclContext();
   MultiLevelTemplateArgumentList SubstArgs(
-      FunctionTemplate, CanonicalDeducedArgumentList->asArray());
+      FunctionTemplate, CanonicalDeducedArgumentList->asArray(),
+      /*Final=*/false);
   Specialization = cast_or_null<FunctionDecl>(
       SubstDecl(FunctionTemplate->getTemplatedDecl(), Owner, SubstArgs));
   if (!Specialization || Specialization->isInvalidDecl())
@@ -4677,7 +4673,8 @@
                                   /*PartialTemplateArgs=*/false,
                                   SugaredConverted, CanonicalConverted))
     return true;
-  MultiLevelTemplateArgumentList MLTAL(Concept, CanonicalConverted);
+  MultiLevelTemplateArgumentList MLTAL(Concept, CanonicalConverted,
+                                       /*Final=*/false);
   if (S.CheckConstraintSatisfaction(Concept, {Concept->getConstraintExpr()},
                                     MLTAL, TypeLoc.getLocalSourceRange(),
                                     Satisfaction))
diff --git a/clang/lib/Sema/SemaTemplateInstantiate.cpp b/clang/lib/Sema/SemaTemplateInstantiate.cpp
--- a/clang/lib/Sema/SemaTemplateInstantiate.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiate.cpp
@@ -94,13 +94,15 @@
   if (VarTemplatePartialSpecializationDecl *Partial =
           Specialized.dyn_cast<VarTemplatePartialSpecializationDecl *>()) {
     Result.addOuterTemplateArguments(
-        Partial, VarTemplSpec->getTemplateInstantiationArgs().asArray());
+        Partial, VarTemplSpec->getTemplateInstantiationArgs().asArray(),
+        /*Final=*/false);
     if (Partial->isMemberSpecialization())
       return Response::Done();
   } else {
     VarTemplateDecl *Tmpl = Specialized.get<VarTemplateDecl *>();
     Result.addOuterTemplateArguments(
-        Tmpl, VarTemplSpec->getTemplateInstantiationArgs().asArray());
+        Tmpl, VarTemplSpec->getTemplateInstantiationArgs().asArray(),
+        /*Final=*/false);
     if (Tmpl->isMemberSpecialization())
       return Response::Done();
   }
@@ -133,7 +135,8 @@
 
     Result.addOuterTemplateArguments(
         const_cast<ClassTemplateSpecializationDecl *>(ClassTemplSpec),
-        ClassTemplSpec->getTemplateInstantiationArgs().asArray());
+        ClassTemplSpec->getTemplateInstantiationArgs().asArray(),
+        /*Final=*/false);
 
     // If this class template specialization was instantiated from a
     // specialized member that is a class template, we're done.
@@ -164,7 +167,8 @@
                  Function->getTemplateSpecializationArgs()) {
     // Add the template arguments for this specialization.
     Result.addOuterTemplateArguments(const_cast<FunctionDecl *>(Function),
-                                     TemplateArgs->asArray());
+                                     TemplateArgs->asArray(),
+                                     /*Final=*/false);
 
     // If this function was instantiated from a specialized member that is
     // a function template, we're done.
@@ -210,7 +214,8 @@
                               ->getInjectedSpecializationType();
       const auto *InjectedType = cast<TemplateSpecializationType>(Injected);
       Result.addOuterTemplateArguments(const_cast<CXXRecordDecl *>(Rec),
-                                       InjectedType->template_arguments());
+                                       InjectedType->template_arguments(),
+                                       /*Final=*/false);
     }
   }
 
@@ -262,7 +267,7 @@
 /// arguments on an enclosing class template.
 
 MultiLevelTemplateArgumentList Sema::getTemplateInstantiationArgs(
-    const NamedDecl *ND, const TemplateArgumentList *Innermost,
+    const NamedDecl *ND, bool Sugared, const TemplateArgumentList *Innermost,
     bool RelativeToPrimary, const FunctionDecl *Pattern,
     bool ForConstraintInstantiation) {
   assert(ND && "Can't find arguments for a decl if one isn't provided");
@@ -271,7 +276,7 @@
 
   if (Innermost)
     Result.addOuterTemplateArguments(const_cast<NamedDecl *>(ND),
-                                     Innermost->asArray());
+                                     Innermost->asArray(), Sugared);
 
   const Decl *CurDecl = ND;
 
@@ -1108,6 +1113,13 @@
       return TemplateArgs.getNewDepth(Depth);
     }
 
+    Optional<unsigned> getPackIndex(TemplateArgument Pack) {
+      int Index = getSema().ArgumentPackSubstitutionIndex;
+      if (Index == -1)
+        return None;
+      return Pack.pack_size() - 1 - Index;
+    }
+
     bool TryExpandParameterPacks(SourceLocation EllipsisLoc,
                                  SourceRange PatternRange,
                                  ArrayRef<UnexpandedParameterPack> Unexpanded,
@@ -1276,16 +1288,26 @@
                                             Optional<unsigned> NumExpansions,
                                             bool ExpectParameterPack);
 
+    using inherited::TransformTemplateTypeParmType;
     /// Transforms a template type parameter type by performing
     /// substitution of the corresponding template type argument.
     QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
-                                           TemplateTypeParmTypeLoc TL);
+                                           TemplateTypeParmTypeLoc TL,
+                                           bool SuppressObjCLifetime);
+
+    QualType BuildSubstTemplateTypeParmType(
+        TypeLocBuilder &TLB, bool SuppressObjCLifetime, bool Sugared,
+        Decl *AssociatedDecl, unsigned Index, Optional<unsigned> PackIndex,
+        TemplateArgument Arg, SourceLocation NameLoc);
 
     /// Transforms an already-substituted template type parameter pack
     /// into either itself (if we aren't substituting into its pack expansion)
     /// or the appropriate substituted argument.
-    QualType TransformSubstTemplateTypeParmPackType(TypeLocBuilder &TLB,
-                                           SubstTemplateTypeParmPackTypeLoc TL);
+    using inherited::TransformSubstTemplateTypeParmPackType;
+    QualType
+    TransformSubstTemplateTypeParmPackType(TypeLocBuilder &TLB,
+                                           SubstTemplateTypeParmPackTypeLoc TL,
+                                           bool SuppressObjCLifetime);
 
     ExprResult TransformLambdaExpr(LambdaExpr *E) {
       LocalInstantiationScope Scope(SemaRef, /*CombineWithOuterScope=*/true);
@@ -1568,7 +1590,8 @@
         return Arg.getAsTemplate();
       }
 
-      Decl *AssociatedDecl = TemplateArgs.getAssociatedDecl(TTP->getDepth());
+      auto [AssociatedDecl, Final] =
+          TemplateArgs.getAssociatedDecl(TTP->getDepth());
       Optional<unsigned> PackIndex;
       if (TTP->isParameterPack()) {
         assert(Arg.getKind() == TemplateArgument::Pack &&
@@ -1579,11 +1602,11 @@
           // actually expanding the enclosing pack expansion yet. So, just
           // keep the entire argument pack.
           return getSema().Context.getSubstTemplateTemplateParmPack(
-              Arg, AssociatedDecl, TTP->getIndex());
+              Arg, AssociatedDecl, TTP->getIndex(), Final);
         }
 
+        PackIndex = getPackIndex(Arg);
         Arg = getPackSubstitutedTemplateArgument(getSema(), Arg);
-        PackIndex = getSema().ArgumentPackSubstitutionIndex;
       }
 
       TemplateName Template = Arg.getAsTemplate().getNameToSubstitute();
@@ -1591,9 +1614,10 @@
       assert(!Template.getAsQualifiedTemplateName() &&
              "template decl to substitute is qualified?");
 
-      Template = getSema().Context.getSubstTemplateTemplateParm(
+      if (Final)
+        return Template;
+      return getSema().Context.getSubstTemplateTemplateParm(
           Template, AssociatedDecl, TTP->getIndex(), PackIndex);
-      return Template;
     }
   }
 
@@ -1602,9 +1626,14 @@
     if (getSema().ArgumentPackSubstitutionIndex == -1)
       return Name;
 
-    TemplateArgument Arg = SubstPack->getArgumentPack();
-    Arg = getPackSubstitutedTemplateArgument(getSema(), Arg);
-    return Arg.getAsTemplate().getNameToSubstitute();
+    TemplateArgument Pack = SubstPack->getArgumentPack();
+    TemplateName Template =
+        getPackSubstitutedTemplateArgument(getSema(), Pack).getAsTemplate();
+    if (SubstPack->getFinal())
+      return Template;
+    return getSema().Context.getSubstTemplateTemplateParm(
+        Template.getNameToSubstitute(), SubstPack->getAssociatedDecl(),
+        SubstPack->getIndex(), getPackIndex(Pack));
   }
 
   return inherited::TransformTemplateName(SS, Name, NameLoc, ObjectType,
@@ -1648,7 +1677,7 @@
     return Arg.getAsExpr();
   }
 
-  Decl *AssociatedDecl = TemplateArgs.getAssociatedDecl(NTTP->getDepth());
+  auto [AssociatedDecl, _] = TemplateArgs.getAssociatedDecl(NTTP->getDepth());
   Optional<unsigned> PackIndex;
   if (NTTP->isParameterPack()) {
     assert(Arg.getKind() == TemplateArgument::Pack &&
@@ -1667,15 +1696,15 @@
       QualType ExprType = TargetType.getNonLValueExprType(SemaRef.Context);
       if (TargetType->isRecordType())
         ExprType.addConst();
-
+      // FIXME: Pass in Final.
       return new (SemaRef.Context) SubstNonTypeTemplateParmPackExpr(
           ExprType, TargetType->isReferenceType() ? VK_LValue : VK_PRValue,
           E->getLocation(), Arg, AssociatedDecl, NTTP->getPosition());
     }
-    PackIndex = getSema().ArgumentPackSubstitutionIndex;
+    PackIndex = getPackIndex(Arg);
     Arg = getPackSubstitutedTemplateArgument(getSema(), Arg);
   }
-
+  // FIXME: Don't put subst node on Final replacement.
   return transformNonTypeTemplateParmRef(AssociatedDecl, NTTP, E->getLocation(),
                                          Arg, PackIndex);
 }
@@ -1767,6 +1796,7 @@
     return ExprError();
 
   Expr *resultExpr = result.get();
+  // FIXME: Don't put subst node on sugared replacement.
   return new (SemaRef.Context) SubstNonTypeTemplateParmExpr(
       resultExpr->getType(), resultExpr->getValueKind(), loc, resultExpr,
       AssociatedDecl, parm->getIndex(), PackIndex, refParam);
@@ -1775,17 +1805,17 @@
 ExprResult
 TemplateInstantiator::TransformSubstNonTypeTemplateParmPackExpr(
                                           SubstNonTypeTemplateParmPackExpr *E) {
-  int PackIndex = getSema().ArgumentPackSubstitutionIndex;
-  if (PackIndex == -1) {
+  if (getSema().ArgumentPackSubstitutionIndex == -1) {
     // We aren't expanding the parameter pack, so just return ourselves.
     return E;
   }
 
-  TemplateArgument Arg = E->getArgumentPack();
-  Arg = getPackSubstitutedTemplateArgument(getSema(), Arg);
+  TemplateArgument Pack = E->getArgumentPack();
+  TemplateArgument Arg = getPackSubstitutedTemplateArgument(getSema(), Pack);
+  // FIXME: Don't put subst node on sugared replacement.
   return transformNonTypeTemplateParmRef(
       E->getAssociatedDecl(), E->getParameterPack(),
-      E->getParameterPackLocation(), Arg, PackIndex);
+      E->getParameterPackLocation(), Arg, getPackIndex(Pack));
 }
 
 ExprResult
@@ -1828,7 +1858,7 @@
     return true;
   return transformNonTypeTemplateParmRef(E->getAssociatedDecl(),
                                          E->getParameter(), E->getExprLoc(),
-                                         CanonicalConverted, E->getPackIndex());
+                                         SugaredConverted, E->getPackIndex());
 }
 
 ExprResult TemplateInstantiator::RebuildVarDeclRefExpr(VarDecl *PD,
@@ -1959,9 +1989,39 @@
   return NewParm;
 }
 
+QualType TemplateInstantiator::BuildSubstTemplateTypeParmType(
+    TypeLocBuilder &TLB, bool SuppressObjCLifetime, bool Final,
+    Decl *AssociatedDecl, unsigned Index, Optional<unsigned> PackIndex,
+    TemplateArgument Arg, SourceLocation NameLoc) {
+  QualType Replacement = Arg.getAsType();
+
+  // If the template parameter had ObjC lifetime qualifiers,
+  // then any such qualifiers on the replacement type are ignored.
+  if (SuppressObjCLifetime) {
+    Qualifiers RQs;
+    RQs = Replacement.getQualifiers();
+    RQs.removeObjCLifetime();
+    Replacement =
+        SemaRef.Context.getQualifiedType(Replacement.getUnqualifiedType(), RQs);
+  }
+
+  if (Final) {
+    TLB.pushTrivial(SemaRef.Context, Replacement, NameLoc);
+    return Replacement;
+  }
+  // TODO: only do this uniquing once, at the start of instantiation.
+  QualType Result = getSema().Context.getSubstTemplateTypeParmType(
+      Replacement, AssociatedDecl, Index, PackIndex);
+  SubstTemplateTypeParmTypeLoc NewTL =
+      TLB.push<SubstTemplateTypeParmTypeLoc>(Result);
+  NewTL.setNameLoc(NameLoc);
+  return Result;
+}
+
 QualType
 TemplateInstantiator::TransformTemplateTypeParmType(TypeLocBuilder &TLB,
-                                                TemplateTypeParmTypeLoc TL) {
+                                                    TemplateTypeParmTypeLoc TL,
+                                                    bool SuppressObjCLifetime) {
   const TemplateTypeParmType *T = TL.getTypePtr();
   if (T->getDepth() < TemplateArgs.getNumLevels()) {
     // Replace the template type parameter with its corresponding
@@ -1998,8 +2058,8 @@
       return NewT;
     }
 
-    Decl *AssociatedDecl =
-        const_cast<Decl *>(TemplateArgs.getAssociatedDecl(T->getDepth()));
+    auto [AssociatedDecl, Final] =
+        TemplateArgs.getAssociatedDecl(T->getDepth());
     Optional<unsigned> PackIndex;
     if (T->isParameterPack()) {
       assert(Arg.getKind() == TemplateArgument::Pack &&
@@ -2010,7 +2070,7 @@
         // enclosing pack expansion yet. Just save the template argument
         // pack for later substitution.
         QualType Result = getSema().Context.getSubstTemplateTypeParmPackType(
-            AssociatedDecl, T->getIndex(), Arg);
+            AssociatedDecl, T->getIndex(), Final, Arg);
         SubstTemplateTypeParmPackTypeLoc NewTL
           = TLB.push<SubstTemplateTypeParmPackTypeLoc>(Result);
         NewTL.setNameLoc(TL.getNameLoc());
@@ -2018,22 +2078,16 @@
       }
 
       // PackIndex starts from last element.
-      PackIndex = Arg.pack_size() - 1 - getSema().ArgumentPackSubstitutionIndex;
+      PackIndex = getPackIndex(Arg);
       Arg = getPackSubstitutedTemplateArgument(getSema(), Arg);
     }
 
     assert(Arg.getKind() == TemplateArgument::Type &&
            "Template argument kind mismatch");
 
-    QualType Replacement = Arg.getAsType();
-
-    // TODO: only do this uniquing once, at the start of instantiation.
-    QualType Result = getSema().Context.getSubstTemplateTypeParmType(
-        Replacement, AssociatedDecl, T->getIndex(), PackIndex);
-    SubstTemplateTypeParmTypeLoc NewTL
-      = TLB.push<SubstTemplateTypeParmTypeLoc>(Result);
-    NewTL.setNameLoc(TL.getNameLoc());
-    return Result;
+    return BuildSubstTemplateTypeParmType(TLB, SuppressObjCLifetime, Final,
+                                          AssociatedDecl, T->getIndex(),
+                                          PackIndex, Arg, TL.getNameLoc());
   }
 
   // The template type parameter comes from an inner template (e.g.,
@@ -2053,7 +2107,8 @@
 }
 
 QualType TemplateInstantiator::TransformSubstTemplateTypeParmPackType(
-    TypeLocBuilder &TLB, SubstTemplateTypeParmPackTypeLoc TL) {
+    TypeLocBuilder &TLB, SubstTemplateTypeParmPackTypeLoc TL,
+    bool SuppressObjCLifetime) {
   const SubstTemplateTypeParmPackType *T = TL.getTypePtr();
 
   Decl *NewReplaced = TransformDecl(TL.getNameLoc(), T->getAssociatedDecl());
@@ -2063,7 +2118,7 @@
     QualType Result = TL.getType();
     if (NewReplaced != T->getAssociatedDecl())
       Result = getSema().Context.getSubstTemplateTypeParmPackType(
-          NewReplaced, T->getIndex(), T->getArgumentPack());
+          NewReplaced, T->getIndex(), T->getFinal(), T->getArgumentPack());
     SubstTemplateTypeParmPackTypeLoc NewTL =
         TLB.push<SubstTemplateTypeParmPackTypeLoc>(Result);
     NewTL.setNameLoc(TL.getNameLoc());
@@ -2072,14 +2127,9 @@
 
   TemplateArgument Pack = T->getArgumentPack();
   TemplateArgument Arg = getPackSubstitutedTemplateArgument(getSema(), Pack);
-  // PackIndex starts from last element.
-  QualType Result = getSema().Context.getSubstTemplateTypeParmType(
-      Arg.getAsType(), NewReplaced, T->getIndex(),
-      Pack.pack_size() - 1 - getSema().ArgumentPackSubstitutionIndex);
-  SubstTemplateTypeParmTypeLoc NewTL =
-      TLB.push<SubstTemplateTypeParmTypeLoc>(Result);
-  NewTL.setNameLoc(TL.getNameLoc());
-  return Result;
+  return BuildSubstTemplateTypeParmType(
+      TLB, SuppressObjCLifetime, T->getFinal(), NewReplaced, T->getIndex(),
+      getPackIndex(Pack), Arg, TL.getNameLoc());
 }
 
 template<typename EntityPrinter>
diff --git a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
--- a/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
+++ b/clang/lib/Sema/SemaTemplateInstantiateDecl.cpp
@@ -4547,8 +4547,8 @@
   //
   // template<typename T>
   // A<T> Foo(int a = A<T>::FooImpl());
-  MultiLevelTemplateArgumentList TemplateArgs
-    = getTemplateInstantiationArgs(FD, nullptr, /*RelativeToPrimary=*/true);
+  MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
+      FD, /*Final=*/false, nullptr, /*RelativeToPrimary=*/true);
 
   if (SubstDefaultArgument(CallLoc, Param, TemplateArgs, /*ForCallExpr*/ true))
     return true;
@@ -4586,8 +4586,8 @@
   Sema::ContextRAII savedContext(*this, Decl);
   LocalInstantiationScope Scope(*this);
 
-  MultiLevelTemplateArgumentList TemplateArgs =
-    getTemplateInstantiationArgs(Decl, nullptr, /*RelativeToPrimary*/true);
+  MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
+      Decl, /*Final=*/false, nullptr, /*RelativeToPrimary*/ true);
 
   // FIXME: We can't use getTemplateInstantiationPattern(false) in general
   // here, because for a non-defining friend declaration in a class template,
@@ -4761,7 +4761,8 @@
     return nullptr;
 
   ContextRAII SavedContext(*this, FD);
-  MultiLevelTemplateArgumentList MArgs(FTD, Args->asArray());
+  MultiLevelTemplateArgumentList MArgs(FTD, Args->asArray(),
+                                       /*Final=*/false);
 
   return cast_or_null<FunctionDecl>(SubstDecl(FD, FD->getParent(), MArgs));
 }
@@ -5027,8 +5028,8 @@
     RebuildTypeSourceInfoForDefaultSpecialMembers();
     SetDeclDefaulted(Function, PatternDecl->getLocation());
   } else {
-    MultiLevelTemplateArgumentList TemplateArgs =
-      getTemplateInstantiationArgs(Function, nullptr, false, PatternDecl);
+    MultiLevelTemplateArgumentList TemplateArgs = getTemplateInstantiationArgs(
+        Function, /*Final=*/false, nullptr, false, PatternDecl);
 
     // Substitute into the qualifier; we can get a substitution failure here
     // through evil use of alias templates.
@@ -5120,13 +5121,13 @@
   if (auto *PartialSpec =
           dyn_cast<VarTemplatePartialSpecializationDecl>(FromVar)) {
     IsMemberSpec = PartialSpec->isMemberSpecialization();
-    MultiLevelList.addOuterTemplateArguments(PartialSpec,
-                                             TemplateArgList.asArray());
+    MultiLevelList.addOuterTemplateArguments(
+        PartialSpec, TemplateArgList.asArray(), /*Final=*/false);
   } else {
     assert(VarTemplate == FromVar->getDescribedVarTemplate());
     IsMemberSpec = VarTemplate->isMemberSpecialization();
-    MultiLevelList.addOuterTemplateArguments(VarTemplate,
-                                             TemplateArgList.asArray());
+    MultiLevelList.addOuterTemplateArguments(
+        VarTemplate, TemplateArgList.asArray(), /*Final=*/false);
   }
   if (!IsMemberSpec)
     FromVar = FromVar->getFirstDecl();
diff --git a/clang/lib/Sema/SemaType.cpp b/clang/lib/Sema/SemaType.cpp
--- a/clang/lib/Sema/SemaType.cpp
+++ b/clang/lib/Sema/SemaType.cpp
@@ -829,8 +829,8 @@
 /// Apply Objective-C type arguments to the given type.
 static QualType applyObjCTypeArgs(Sema &S, SourceLocation loc, QualType type,
                                   ArrayRef<TypeSourceInfo *> typeArgs,
-                                  SourceRange typeArgsRange,
-                                  bool failOnError = false) {
+                                  SourceRange typeArgsRange, bool failOnError,
+                                  bool rebuilding) {
   // We can only apply type arguments to an Objective-C class type.
   const auto *objcObjectType = type->getAs<ObjCObjectType>();
   if (!objcObjectType || !objcObjectType->getInterface()) {
@@ -894,7 +894,9 @@
         }
       }
 
-      if (!diagnosed) {
+      // When rebuilding, qualifiers might have gotten here through a
+      // sugared substitution.
+      if (!rebuilding && !diagnosed) {
         S.Diag(qual.getBeginLoc(), diag::err_objc_type_arg_qualified)
             << typeArg << typeArg.getQualifiers().getAsString()
             << FixItHint::CreateRemoval(rangeToRemove);
@@ -1056,22 +1058,18 @@
   return Result;
 }
 
-QualType Sema::BuildObjCObjectType(QualType BaseType,
-                                   SourceLocation Loc,
-                                   SourceLocation TypeArgsLAngleLoc,
-                                   ArrayRef<TypeSourceInfo *> TypeArgs,
-                                   SourceLocation TypeArgsRAngleLoc,
-                                   SourceLocation ProtocolLAngleLoc,
-                                   ArrayRef<ObjCProtocolDecl *> Protocols,
-                                   ArrayRef<SourceLocation> ProtocolLocs,
-                                   SourceLocation ProtocolRAngleLoc,
-                                   bool FailOnError) {
+QualType Sema::BuildObjCObjectType(
+    QualType BaseType, SourceLocation Loc, SourceLocation TypeArgsLAngleLoc,
+    ArrayRef<TypeSourceInfo *> TypeArgs, SourceLocation TypeArgsRAngleLoc,
+    SourceLocation ProtocolLAngleLoc, ArrayRef<ObjCProtocolDecl *> Protocols,
+    ArrayRef<SourceLocation> ProtocolLocs, SourceLocation ProtocolRAngleLoc,
+    bool FailOnError, bool Rebuilding) {
   QualType Result = BaseType;
   if (!TypeArgs.empty()) {
-    Result = applyObjCTypeArgs(*this, Loc, Result, TypeArgs,
-                               SourceRange(TypeArgsLAngleLoc,
-                                           TypeArgsRAngleLoc),
-                               FailOnError);
+    Result =
+        applyObjCTypeArgs(*this, Loc, Result, TypeArgs,
+                          SourceRange(TypeArgsLAngleLoc, TypeArgsRAngleLoc),
+                          FailOnError, Rebuilding);
     if (FailOnError && Result.isNull())
       return QualType();
   }
@@ -1170,10 +1168,11 @@
       T, BaseTypeInfo->getTypeLoc().getSourceRange().getBegin(),
       TypeArgsLAngleLoc, ActualTypeArgInfos, TypeArgsRAngleLoc,
       ProtocolLAngleLoc,
-      llvm::makeArrayRef((ObjCProtocolDecl * const *)Protocols.data(),
+      llvm::makeArrayRef((ObjCProtocolDecl *const *)Protocols.data(),
                          Protocols.size()),
       ProtocolLocs, ProtocolRAngleLoc,
-      /*FailOnError=*/false);
+      /*FailOnError=*/false,
+      /*Rebuilding=*/false);
 
   if (Result == T)
     return BaseType;
diff --git a/clang/lib/Sema/TreeTransform.h b/clang/lib/Sema/TreeTransform.h
--- a/clang/lib/Sema/TreeTransform.h
+++ b/clang/lib/Sema/TreeTransform.h
@@ -636,6 +636,14 @@
   QualType Transform##CLASS##Type(TypeLocBuilder &TLB, CLASS##TypeLoc T);
 #include "clang/AST/TypeLocNodes.def"
 
+  QualType TransformTemplateTypeParmType(TypeLocBuilder &TLB,
+                                         TemplateTypeParmTypeLoc TL,
+                                         bool SuppressObjCLifetime);
+  QualType
+  TransformSubstTemplateTypeParmPackType(TypeLocBuilder &TLB,
+                                         SubstTemplateTypeParmPackTypeLoc TL,
+                                         bool SuppressObjCLifetime);
+
   template<typename Fn>
   QualType TransformFunctionProtoType(TypeLocBuilder &TLB,
                                       FunctionProtoTypeLoc TL,
@@ -1286,9 +1294,10 @@
   /// template name. Subclasses may override this routine to provide different
   /// behavior.
   TemplateName RebuildTemplateName(const TemplateArgument &ArgPack,
-                                   Decl *AssociatedDecl, unsigned Index) {
+                                   Decl *AssociatedDecl, unsigned Index,
+                                   bool Final) {
     return getSema().Context.getSubstTemplateTemplateParmPack(
-        ArgPack, AssociatedDecl, Index);
+        ArgPack, AssociatedDecl, Index, Final);
   }
 
   /// Build a new compound statement.
@@ -4153,9 +4162,13 @@
     NestedNameSpecifierLoc NNS, QualType ObjectType,
     NamedDecl *FirstQualifierInScope) {
   SmallVector<NestedNameSpecifierLoc, 4> Qualifiers;
-  for (NestedNameSpecifierLoc Qualifier = NNS; Qualifier;
-       Qualifier = Qualifier.getPrefix())
-    Qualifiers.push_back(Qualifier);
+
+  auto insertNNS = [&Qualifiers](NestedNameSpecifierLoc NNS) {
+    for (NestedNameSpecifierLoc Qualifier = NNS; Qualifier;
+         Qualifier = Qualifier.getPrefix())
+      Qualifiers.push_back(Qualifier);
+  };
+  insertNNS(NNS);
 
   CXXScopeSpec SS;
   while (!Qualifiers.empty()) {
@@ -4212,14 +4225,17 @@
       if (!TL)
         return NestedNameSpecifierLoc();
 
-      if (TL.getType()->isDependentType() || TL.getType()->isRecordType() ||
-          (SemaRef.getLangOpts().CPlusPlus11 &&
-           TL.getType()->isEnumeralType())) {
-        assert(!TL.getType().hasLocalQualifiers() &&
-               "Can't get cv-qualifiers here");
-        if (TL.getType()->isEnumeralType())
+      QualType T = TL.getType();
+      if (T->isDependentType() || T->isRecordType() ||
+          (SemaRef.getLangOpts().CPlusPlus11 && T->isEnumeralType())) {
+        if (T->isEnumeralType())
           SemaRef.Diag(TL.getBeginLoc(),
                        diag::warn_cxx98_compat_enum_nested_name_spec);
+
+        if (const auto ETL = TL.getAs<ElaboratedTypeLoc>()) {
+          SS.Adopt(ETL.getQualifierLoc());
+          TL = ETL.getNamedTypeLoc();
+        }
         SS.Extend(SemaRef.Context, /*FIXME:*/ SourceLocation(), TL,
                   Q.getLocalEndLoc());
         break;
@@ -4229,7 +4245,7 @@
       TypedefTypeLoc TTL = TL.getAsAdjusted<TypedefTypeLoc>();
       if (!TTL || !TTL.getTypedefNameDecl()->isInvalidDecl()) {
         SemaRef.Diag(TL.getBeginLoc(), diag::err_nested_name_spec_non_tag)
-            << TL.getType() << SS.getRange();
+            << T << SS.getRange();
       }
       return NestedNameSpecifierLoc();
     }
@@ -4392,9 +4408,9 @@
 
   if (SubstTemplateTemplateParmPackStorage *SubstPack
       = Name.getAsSubstTemplateTemplateParmPack()) {
-    return getDerived().RebuildTemplateName(SubstPack->getArgumentPack(),
-                                            SubstPack->getAssociatedDecl(),
-                                            SubstPack->getIndex());
+    return getDerived().RebuildTemplateName(
+        SubstPack->getArgumentPack(), SubstPack->getAssociatedDecl(),
+        SubstPack->getIndex(), SubstPack->getFinal());
   }
 
   // These should be getting filtered out before they reach the AST.
@@ -4808,7 +4824,20 @@
 QualType
 TreeTransform<Derived>::TransformQualifiedType(TypeLocBuilder &TLB,
                                                QualifiedTypeLoc T) {
-  QualType Result = getDerived().TransformType(TLB, T.getUnqualifiedLoc());
+  QualType Result;
+  TypeLoc UnqualTL = T.getUnqualifiedLoc();
+  auto SuppressObjCLifetime =
+      T.getType().getLocalQualifiers().hasObjCLifetime();
+  if (auto TTP = UnqualTL.getAs<TemplateTypeParmTypeLoc>()) {
+    Result = getDerived().TransformTemplateTypeParmType(TLB, TTP,
+                                                        SuppressObjCLifetime);
+  } else if (auto STTP = UnqualTL.getAs<SubstTemplateTypeParmPackTypeLoc>()) {
+    Result = getDerived().TransformSubstTemplateTypeParmPackType(
+        TLB, STTP, SuppressObjCLifetime);
+  } else {
+    Result = getDerived().TransformType(TLB, UnqualTL);
+  }
+
   if (Result.isNull())
     return QualType();
 
@@ -4871,17 +4900,7 @@
       //   A lifetime qualifier applied to a substituted template parameter
       //   overrides the lifetime qualifier from the template argument.
       const AutoType *AutoTy;
-      if (const SubstTemplateTypeParmType *SubstTypeParam
-                                = dyn_cast<SubstTemplateTypeParmType>(T)) {
-        QualType Replacement = SubstTypeParam->getReplacementType();
-        Qualifiers Qs = Replacement.getQualifiers();
-        Qs.removeObjCLifetime();
-        Replacement = SemaRef.Context.getQualifiedType(
-            Replacement.getUnqualifiedType(), Qs);
-        T = SemaRef.Context.getSubstTemplateTypeParmType(
-            Replacement, SubstTypeParam->getAssociatedDecl(),
-            SubstTypeParam->getIndex(), SubstTypeParam->getPackIndex());
-      } else if ((AutoTy = dyn_cast<AutoType>(T)) && AutoTy->isDeduced()) {
+      if ((AutoTy = dyn_cast<AutoType>(T)) && AutoTy->isDeduced()) {
         // 'auto' types behave the same way as template parameters.
         QualType Deduced = AutoTy->getDeducedType();
         Qualifiers Qs = Deduced.getQualifiers();
@@ -6423,6 +6442,14 @@
 QualType TreeTransform<Derived>::TransformTemplateTypeParmType(
                                                 TypeLocBuilder &TLB,
                                                 TemplateTypeParmTypeLoc TL) {
+  return getDerived().TransformTemplateTypeParmType(
+      TLB, TL,
+      /*SuppressObjCLifetime=*/false);
+}
+
+template <typename Derived>
+QualType TreeTransform<Derived>::TransformTemplateTypeParmType(
+    TypeLocBuilder &TLB, TemplateTypeParmTypeLoc TL, bool) {
   return TransformTypeSpecType(TLB, TL);
 }
 
@@ -6458,6 +6485,13 @@
 QualType TreeTransform<Derived>::TransformSubstTemplateTypeParmPackType(
                                           TypeLocBuilder &TLB,
                                           SubstTemplateTypeParmPackTypeLoc TL) {
+  return getDerived().TransformSubstTemplateTypeParmPackType(
+      TLB, TL, /*SuppressObjCLifetime=*/false);
+}
+
+template <typename Derived>
+QualType TreeTransform<Derived>::TransformSubstTemplateTypeParmPackType(
+    TypeLocBuilder &TLB, SubstTemplateTypeParmPackTypeLoc TL, bool) {
   return TransformTypeSpecType(TLB, TL);
 }
 
@@ -7244,7 +7278,8 @@
 
     TypeLocBuilder TypeArgBuilder;
     TypeArgBuilder.reserve(TypeArgLoc.getFullDataSize());
-    QualType NewTypeArg = getDerived().TransformType(TypeArgBuilder, TypeArgLoc);
+    QualType NewTypeArg =
+        getDerived().TransformType(TypeArgBuilder, TypeArgLoc);
     if (NewTypeArg.isNull())
       return QualType();
 
@@ -14533,11 +14568,11 @@
            ArrayRef<ObjCProtocolDecl *> Protocols,
            ArrayRef<SourceLocation> ProtocolLocs,
            SourceLocation ProtocolRAngleLoc) {
-  return SemaRef.BuildObjCObjectType(BaseType, Loc, TypeArgsLAngleLoc,
-                                     TypeArgs, TypeArgsRAngleLoc,
-                                     ProtocolLAngleLoc, Protocols, ProtocolLocs,
-                                     ProtocolRAngleLoc,
-                                     /*FailOnError=*/true);
+  return SemaRef.BuildObjCObjectType(BaseType, Loc, TypeArgsLAngleLoc, TypeArgs,
+                                     TypeArgsRAngleLoc, ProtocolLAngleLoc,
+                                     Protocols, ProtocolLocs, ProtocolRAngleLoc,
+                                     /*FailOnError=*/true,
+                                     /*Rebuilding=*/true);
 }
 
 template<typename Derived>
diff --git a/clang/lib/Sema/TypeLocBuilder.h b/clang/lib/Sema/TypeLocBuilder.h
--- a/clang/lib/Sema/TypeLocBuilder.h
+++ b/clang/lib/Sema/TypeLocBuilder.h
@@ -64,6 +64,10 @@
   /// must be empty for this to work.
   void pushFullCopy(TypeLoc L);
 
+  /// Pushes 'T' with all locations pointing to 'Loc'.
+  /// The builder must be empty for this to work.
+  void pushTrivial(ASTContext &Context, QualType T, SourceLocation Loc);
+
   /// Pushes space for a typespec TypeLoc.  Invalidates any TypeLocs
   /// previously retrieved from this builder.
   TypeSpecTypeLoc pushTypeSpec(QualType T) {
diff --git a/clang/lib/Sema/TypeLocBuilder.cpp b/clang/lib/Sema/TypeLocBuilder.cpp
--- a/clang/lib/Sema/TypeLocBuilder.cpp
+++ b/clang/lib/Sema/TypeLocBuilder.cpp
@@ -41,6 +41,29 @@
   }
 }
 
+void TypeLocBuilder::pushTrivial(ASTContext &Context, QualType T,
+                                 SourceLocation Loc) {
+  auto L = TypeLoc(T, nullptr);
+  reserve(L.getFullDataSize());
+
+  SmallVector<TypeLoc, 4> TypeLocs;
+  for (auto CurTL = L; CurTL; CurTL = CurTL.getNextTypeLoc())
+    TypeLocs.push_back(CurTL);
+
+  for (const auto &CurTL : llvm::reverse(TypeLocs)) {
+    switch (CurTL.getTypeLocClass()) {
+#define ABSTRACT_TYPELOC(CLASS, PARENT)
+#define TYPELOC(CLASS, PARENT)                                                 \
+  case TypeLoc::CLASS: {                                                       \
+    auto NewTL = push<class CLASS##TypeLoc>(CurTL.getType());                  \
+    NewTL.initializeLocal(Context, Loc);                                       \
+    break;                                                                     \
+  }
+#include "clang/AST/TypeLocNodes.def"
+    }
+  }
+}
+
 void TypeLocBuilder::grow(size_t NewCapacity) {
   assert(NewCapacity > Capacity);
 
diff --git a/clang/test/SemaTemplate/nested-name-spec-template.cpp b/clang/test/SemaTemplate/nested-name-spec-template.cpp
--- a/clang/test/SemaTemplate/nested-name-spec-template.cpp
+++ b/clang/test/SemaTemplate/nested-name-spec-template.cpp
@@ -147,3 +147,10 @@
 
   template void f<int>(); // expected-note{{in instantiation of}}
 }
+
+namespace sugared_template_instantiation {
+  // Test that we ignore local qualifiers.
+  template <class A1, class = typename A1::type1> struct A {};
+  struct B { typedef int type1; };
+  typedef A<const B> type2;
+} // namespace sugated_template_instantiation
diff --git a/libcxx/DELETE.ME b/libcxx/DELETE.ME
new file mode 100644
--- /dev/null
+++ b/libcxx/DELETE.ME
@@ -0,0 +1 @@
+D134604