diff --git include/clang/AST/Type.h include/clang/AST/Type.h
index bd2e188..f927f5d 100644
--- include/clang/AST/Type.h
+++ include/clang/AST/Type.h
@@ -4169,8 +4169,8 @@ public:
     return None;
   }
 
-  bool isSugared() const { return false; }
-  QualType desugar() const { return QualType(this, 0); }
+  bool isSugared() const { return !Pattern->isDependentType(); }
+  QualType desugar() const { return isSugared() ? Pattern : QualType(this, 0); }
 
   void Profile(llvm::FoldingSetNodeID &ID) {
     Profile(ID, getPattern(), getNumExpansions());
diff --git include/clang/AST/TypeNodes.def include/clang/AST/TypeNodes.def
index 840e07d..2e8fc89 100644
--- include/clang/AST/TypeNodes.def
+++ include/clang/AST/TypeNodes.def
@@ -98,7 +98,7 @@ TYPE(Auto, Type)
 DEPENDENT_TYPE(InjectedClassName, Type)
 DEPENDENT_TYPE(DependentName, Type)
 DEPENDENT_TYPE(DependentTemplateSpecialization, Type)
-DEPENDENT_TYPE(PackExpansion, Type)
+NON_CANONICAL_UNLESS_DEPENDENT_TYPE(PackExpansion, Type)
 TYPE(ObjCObject, Type)
 TYPE(ObjCInterface, ObjCObjectType)
 TYPE(ObjCObjectPointer, Type)
diff --git lib/AST/ASTContext.cpp lib/AST/ASTContext.cpp
index 70c933e..7d3fcb2 100644
--- lib/AST/ASTContext.cpp
+++ lib/AST/ASTContext.cpp
@@ -1423,6 +1423,10 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
 #define ABSTRACT_TYPE(Class, Base)
 #define NON_CANONICAL_TYPE(Class, Base)
 #define DEPENDENT_TYPE(Class, Base) case Type::Class:
+#define NON_CANONICAL_UNLESS_DEPENDENT_TYPE(Class, Base)                       \
+  case Type::Class:                                                            \
+  assert(!T->isDependentType() && "...");                                      \
+  return getTypeInfo(cast<Class##Type>(T)->desugar().getTypePtr());
 #include "clang/AST/TypeNodes.def"
     llvm_unreachable("Should not see dependent types");
 
@@ -1671,20 +1675,6 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
     break;
   }
 
-  case Type::TypeOfExpr:
-    return getTypeInfo(cast<TypeOfExprType>(T)->getUnderlyingExpr()->getType()
-                         .getTypePtr());
-
-  case Type::TypeOf:
-    return getTypeInfo(cast<TypeOfType>(T)->getUnderlyingType().getTypePtr());
-
-  case Type::Decltype:
-    return getTypeInfo(cast<DecltypeType>(T)->getUnderlyingExpr()->getType()
-                        .getTypePtr());
-
-  case Type::UnaryTransform:
-    return getTypeInfo(cast<UnaryTransformType>(T)->getUnderlyingType());
-
   case Type::Elaborated:
     return getTypeInfo(cast<ElaboratedType>(T)->getNamedType().getTypePtr());
 
@@ -1692,18 +1682,6 @@ ASTContext::getTypeInfoImpl(const Type *T) const {
     return getTypeInfo(
                   cast<AttributedType>(T)->getEquivalentType().getTypePtr());
 
-  case Type::TemplateSpecialization: {
-    assert(getCanonicalType(T) != T &&
-           "Cannot request the size of a dependent type");
-    const TemplateSpecializationType *TST = cast<TemplateSpecializationType>(T);
-    // A type alias template specialization may refer to a typedef with the
-    // aligned attribute on it.
-    if (TST->isTypeAlias())
-      return getTypeInfo(TST->getAliasedType().getTypePtr());
-    else
-      return getTypeInfo(getCanonicalType(T));
-  }
-
   case Type::Atomic: {
     // Start with the base type information.
     std::pair<uint64_t, unsigned> Info
diff --git lib/CodeGen/CGDebugInfo.cpp lib/CodeGen/CGDebugInfo.cpp
index db08924..5277cfa 100644
--- lib/CodeGen/CGDebugInfo.cpp
+++ lib/CodeGen/CGDebugInfo.cpp
@@ -2089,6 +2089,7 @@ llvm::DIType CGDebugInfo::CreateTypeNode(QualType Ty, llvm::DIFile Unit,
   case Type::TypeOf:
   case Type::Decltype:
   case Type::UnaryTransform:
+  case Type::PackExpansion:
     llvm_unreachable("type should have been unwrapped!");
   case Type::Auto:
     Diag = "auto";
diff --git lib/CodeGen/CodeGenFunction.cpp lib/CodeGen/CodeGenFunction.cpp
index 297fc65..cc456ae 100644
--- lib/CodeGen/CodeGenFunction.cpp
+++ lib/CodeGen/CodeGenFunction.cpp
@@ -1344,6 +1344,7 @@ void CodeGenFunction::EmitVariablyModifiedType(QualType type) {
     case Type::UnaryTransform:
     case Type::Attributed:
     case Type::SubstTemplateTypeParm:
+    case Type::PackExpansion:
       // Keep walking after single level desugaring.
       type = type.getSingleStepDesugaredType(getContext());
       break;