diff --git a/clang/include/clang/Serialization/ASTReader.h b/clang/include/clang/Serialization/ASTReader.h
index 24fc070ec120..60f212929559 100644
--- a/clang/include/clang/Serialization/ASTReader.h
+++ b/clang/include/clang/Serialization/ASTReader.h
@@ -224,6 +224,7 @@ private:
   /// First (not depending on another) PCH in chain is in front.
   std::vector<llvm::MemoryBuffer *> ASTBuffers;
 
+public:
   /// \brief Information that is needed for every module.
   struct PerFileData {
     PerFileData(ASTFileType Ty);
@@ -436,7 +437,8 @@ private:
     /// directly loaded modules.
     SmallVector<PerFileData *, 1> Loaders;
   };
-
+private:
+  
   /// \brief All loaded modules, indexed by name.
   llvm::StringMap<PerFileData*> Modules;
 
@@ -1121,11 +1123,51 @@ public:
   /// marked as "doesn't exist in AST".
   serialization::TypeIdx GetTypeIdx(QualType T) const;
 
+  /// \brief Map from a local declaration ID within a given module to a 
+  /// global declaration ID.
+  serialization::DeclID getGlobalDeclID(PerFileData &F, unsigned LocalID) const;
+  
   /// \brief Resolve a declaration ID into a declaration, potentially
   /// building a new declaration.
   Decl *GetDecl(serialization::DeclID ID);
   virtual Decl *GetExternalDecl(uint32_t ID);
 
+  /// \brief Reads a declaration with the given local ID in the give module.
+  Decl *GetLocalDecl(PerFileData &F, uint32_t LocalID) {
+    return GetDecl(getGlobalDeclID(F, LocalID));
+  }
+
+  /// \brief Reads a declaration with the given local ID in the give module.
+  ///
+  /// \returns The requested declaration, casted to the given return type.
+  template<typename T>
+  T *GetLocalDeclAs(PerFileData &F, uint32_t LocalID) {
+    return cast_or_null<T>(GetLocalDecl(F, LocalID));
+  }
+
+  /// \brief Reads a declaration ID from the given position in a record in the 
+  /// given module.
+  ///
+  /// \returns The declaration ID read from the record, adjusted to a global ID.
+  serialization::DeclID ReadDeclID(PerFileData &F, const RecordData &Record,
+                                   unsigned &Idx);
+  
+  /// \brief Reads a declaration from the given position in a record in the
+  /// given module.
+  Decl *ReadDecl(PerFileData &F, const RecordData &R, unsigned &I) {
+    return GetDecl(ReadDeclID(F, R, I));
+  }
+  
+  /// \brief Reads a declaration from the given position in a record in the
+  /// given module.
+  ///
+  /// \returns The declaration read from this location, casted to the given
+  /// result type.
+  template<typename T>
+  T *ReadDeclAs(PerFileData &F, const RecordData &R, unsigned &I) {
+    return cast_or_null<T>(GetDecl(ReadDeclID(F, R, I)));
+  }
+
   /// \brief Resolve a CXXBaseSpecifiers ID into an offset into the chain
   /// of loaded AST files.
   uint64_t GetCXXBaseSpecifiersOffset(serialization::CXXBaseSpecifiersID ID);
@@ -1279,7 +1321,8 @@ public:
   void ReadQualifierInfo(PerFileData &F, QualifierInfo &Info,
                          const RecordData &Record, unsigned &Idx);
 
-  NestedNameSpecifier *ReadNestedNameSpecifier(const RecordData &Record,
+  NestedNameSpecifier *ReadNestedNameSpecifier(PerFileData &F,
+                                               const RecordData &Record,
                                                unsigned &Idx);
 
   NestedNameSpecifierLoc ReadNestedNameSpecifierLoc(PerFileData &F, 
@@ -1306,7 +1349,7 @@ public:
                            unsigned &Idx);
 
   /// \brief Read a UnresolvedSet structure.
-  void ReadUnresolvedSet(UnresolvedSetImpl &Set,
+  void ReadUnresolvedSet(PerFileData &F, UnresolvedSetImpl &Set,
                          const RecordData &Record, unsigned &Idx);
 
   /// \brief Read a C++ base specifier.
@@ -1356,7 +1399,8 @@ public:
   /// \brief Read a version tuple.
   VersionTuple ReadVersionTuple(const RecordData &Record, unsigned &Idx);
 
-  CXXTemporary *ReadCXXTemporary(const RecordData &Record, unsigned &Idx);
+  CXXTemporary *ReadCXXTemporary(PerFileData &F, const RecordData &Record, 
+                                 unsigned &Idx);
       
   /// \brief Reads attributes from the current stream position.
   void ReadAttributes(PerFileData &F, AttrVec &Attrs,
diff --git a/clang/lib/Serialization/ASTReader.cpp b/clang/lib/Serialization/ASTReader.cpp
index c8f5db214c0a..74fbd6cc5e27 100644
--- a/clang/lib/Serialization/ASTReader.cpp
+++ b/clang/lib/Serialization/ASTReader.cpp
@@ -483,7 +483,8 @@ ASTReader::setDeserializationListener(ASTDeserializationListener *Listener) {
 namespace {
 class ASTSelectorLookupTrait {
   ASTReader &Reader;
-
+  ASTReader::PerFileData &F;
+  
 public:
   struct data_type {
     SelectorID ID;
@@ -493,7 +494,8 @@ public:
   typedef Selector external_key_type;
   typedef external_key_type internal_key_type;
 
-  explicit ASTSelectorLookupTrait(ASTReader &Reader) : Reader(Reader) { }
+  ASTSelectorLookupTrait(ASTReader &Reader, ASTReader::PerFileData &F) 
+    : Reader(Reader), F(F) { }
 
   static bool EqualKey(const internal_key_type& a,
                        const internal_key_type& b) {
@@ -548,7 +550,7 @@ public:
     ObjCMethodList *Prev = 0;
     for (unsigned I = 0; I != NumInstanceMethods; ++I) {
       ObjCMethodDecl *Method
-        = cast<ObjCMethodDecl>(Reader.GetDecl(ReadUnalignedLE32(d)));
+        = Reader.GetLocalDeclAs<ObjCMethodDecl>(F, ReadUnalignedLE32(d));
       if (!Result.Instance.Method) {
         // This is the first method, which is the easy case.
         Result.Instance.Method = Method;
@@ -566,7 +568,7 @@ public:
     Prev = 0;
     for (unsigned I = 0; I != NumFactoryMethods; ++I) {
       ObjCMethodDecl *Method
-        = cast<ObjCMethodDecl>(Reader.GetDecl(ReadUnalignedLE32(d)));
+        = Reader.GetLocalDeclAs<ObjCMethodDecl>(F, ReadUnalignedLE32(d));
       if (!Result.Factory.Method) {
         // This is the first method, which is the easy case.
         Result.Factory.Method = Method;
@@ -2135,12 +2137,8 @@ ASTReader::ReadASTBlock(PerFileData &F) {
       break;
 
     case EXTERNAL_DEFINITIONS:
-      // Optimization for the first block.
-      if (ExternalDefinitions.empty())
-        ExternalDefinitions.swap(Record);
-      else
-        ExternalDefinitions.insert(ExternalDefinitions.end(),
-                                   Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        ExternalDefinitions.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case SPECIAL_TYPES:
@@ -2159,21 +2157,13 @@ ASTReader::ReadASTBlock(PerFileData &F) {
       break;
 
     case UNUSED_FILESCOPED_DECLS:
-      // Optimization for the first block.
-      if (UnusedFileScopedDecls.empty())
-        UnusedFileScopedDecls.swap(Record);
-      else
-        UnusedFileScopedDecls.insert(UnusedFileScopedDecls.end(),
-                                     Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        UnusedFileScopedDecls.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case DELEGATING_CTORS:
-      // Optimization for the first block.
-      if (DelegatingCtorDecls.empty())
-        DelegatingCtorDecls.swap(Record);
-      else
-        DelegatingCtorDecls.insert(DelegatingCtorDecls.end(),
-                                   Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        DelegatingCtorDecls.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case WEAK_UNDECLARED_IDENTIFIERS:
@@ -2182,12 +2172,8 @@ ASTReader::ReadASTBlock(PerFileData &F) {
       break;
 
     case LOCALLY_SCOPED_EXTERNAL_DECLS:
-      // Optimization for the first block.
-      if (LocallyScopedExternalDecls.empty())
-        LocallyScopedExternalDecls.swap(Record);
-      else
-        LocallyScopedExternalDecls.insert(LocallyScopedExternalDecls.end(),
-                                          Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        LocallyScopedExternalDecls.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case SELECTOR_OFFSETS:
@@ -2210,7 +2196,7 @@ ASTReader::ReadASTBlock(PerFileData &F) {
           = ASTSelectorLookupTable::Create(
                         F.SelectorLookupTableData + Record[0],
                         F.SelectorLookupTableData,
-                        ASTSelectorLookupTrait(*this));
+                        ASTSelectorLookupTrait(*this, F));
       TotalNumMethodPoolEntries += Record[1];
       break;
 
@@ -2301,35 +2287,34 @@ ASTReader::ReadASTBlock(PerFileData &F) {
     }
 
     case EXT_VECTOR_DECLS:
-      // Optimization for the first block.
-      if (ExtVectorDecls.empty())
-        ExtVectorDecls.swap(Record);
-      else
-        ExtVectorDecls.insert(ExtVectorDecls.end(),
-                              Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        ExtVectorDecls.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case VTABLE_USES:
       // Later tables overwrite earlier ones.
-      VTableUses.swap(Record);
+      // FIXME: Modules will have some trouble with this.
+      VTableUses.clear();
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        VTableUses.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case DYNAMIC_CLASSES:
-      // Optimization for the first block.
-      if (DynamicClasses.empty())
-        DynamicClasses.swap(Record);
-      else
-        DynamicClasses.insert(DynamicClasses.end(),
-                              Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        DynamicClasses.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case PENDING_IMPLICIT_INSTANTIATIONS:
-      F.PendingInstantiations.swap(Record);
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        F.PendingInstantiations.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case SEMA_DECL_REFS:
       // Later tables overwrite earlier ones.
-      SemaDeclRefs.swap(Record);
+      // FIXME: Modules will have some trouble with this.
+      SemaDeclRefs.clear();
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        SemaDeclRefs.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case ORIGINAL_FILE_NAME:
@@ -2456,7 +2441,10 @@ ASTReader::ReadASTBlock(PerFileData &F) {
         
     case CUDA_SPECIAL_DECL_REFS:
       // Later tables overwrite earlier ones.
-      CUDASpecialDeclRefs.swap(Record);
+      // FIXME: Modules will have trouble with this.
+      CUDASpecialDeclRefs.clear();
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        CUDASpecialDeclRefs.push_back(getGlobalDeclID(F, Record[I]));
       break;
 
     case HEADER_SEARCH_TABLE:
@@ -2483,21 +2471,13 @@ ASTReader::ReadASTBlock(PerFileData &F) {
       break;
 
     case TENTATIVE_DEFINITIONS:
-      // Optimization for the first block.
-      if (TentativeDefinitions.empty())
-        TentativeDefinitions.swap(Record);
-      else
-        TentativeDefinitions.insert(TentativeDefinitions.end(),
-                                    Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        TentativeDefinitions.push_back(getGlobalDeclID(F, Record[I]));
       break;
         
     case KNOWN_NAMESPACES:
-      // Optimization for the first block.
-      if (KnownNamespaces.empty())
-        KnownNamespaces.swap(Record);
-      else
-        KnownNamespaces.insert(KnownNamespaces.end(), 
-                               Record.begin(), Record.end());
+      for (unsigned I = 0, N = Record.size(); I != N; ++I)
+        KnownNamespaces.push_back(getGlobalDeclID(F, Record[I]));
       break;
     }
     First = false;
@@ -3377,16 +3357,19 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
                                     EPI);
   }
 
-  case TYPE_UNRESOLVED_USING:
+  case TYPE_UNRESOLVED_USING: {
+    unsigned Idx = 0;
     return Context->getTypeDeclType(
-             cast<UnresolvedUsingTypenameDecl>(GetDecl(Record[0])));
-
+                  ReadDeclAs<UnresolvedUsingTypenameDecl>(*Loc.F, Record, Idx));
+  }
+      
   case TYPE_TYPEDEF: {
     if (Record.size() != 2) {
       Error("incorrect encoding of typedef type");
       return QualType();
     }
-    TypedefNameDecl *Decl = cast<TypedefNameDecl>(GetDecl(Record[0]));
+    unsigned Idx = 0;
+    TypedefNameDecl *Decl = ReadDeclAs<TypedefNameDecl>(*Loc.F, Record, Idx);
     QualType Canonical = GetType(Record[1]);
     if (!Canonical.isNull())
       Canonical = Context->getCanonicalType(Canonical);
@@ -3423,8 +3406,10 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
       Error("incorrect encoding of record type");
       return QualType();
     }
-    bool IsDependent = Record[0];
-    QualType T = Context->getRecordType(cast<RecordDecl>(GetDecl(Record[1])));
+    unsigned Idx = 0;
+    bool IsDependent = Record[Idx++];
+    QualType T
+      = Context->getRecordType(ReadDeclAs<RecordDecl>(*Loc.F, Record, Idx));
     const_cast<Type*>(T.getTypePtr())->setDependent(IsDependent);
     return T;
   }
@@ -3434,8 +3419,10 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
       Error("incorrect encoding of enum type");
       return QualType();
     }
-    bool IsDependent = Record[0];
-    QualType T = Context->getEnumType(cast<EnumDecl>(GetDecl(Record[1])));
+    unsigned Idx = 0;
+    bool IsDependent = Record[Idx++];
+    QualType T
+      = Context->getEnumType(ReadDeclAs<EnumDecl>(*Loc.F, Record, Idx));
     const_cast<Type*>(T.getTypePtr())->setDependent(IsDependent);
     return T;
   }
@@ -3477,14 +3464,15 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
   case TYPE_ELABORATED: {
     unsigned Idx = 0;
     ElaboratedTypeKeyword Keyword = (ElaboratedTypeKeyword)Record[Idx++];
-    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(Record, Idx);
+    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(*Loc.F, Record, Idx);
     QualType NamedType = GetType(Record[Idx++]);
     return Context->getElaboratedType(Keyword, NNS, NamedType);
   }
 
   case TYPE_OBJC_INTERFACE: {
     unsigned Idx = 0;
-    ObjCInterfaceDecl *ItfD = cast<ObjCInterfaceDecl>(GetDecl(Record[Idx++]));
+    ObjCInterfaceDecl *ItfD
+      = ReadDeclAs<ObjCInterfaceDecl>(*Loc.F, Record, Idx);
     return Context->getObjCInterfaceType(ItfD);
   }
 
@@ -3494,7 +3482,7 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
     unsigned NumProtos = Record[Idx++];
     llvm::SmallVector<ObjCProtocolDecl*, 4> Protos;
     for (unsigned I = 0; I != NumProtos; ++I)
-      Protos.push_back(cast<ObjCProtocolDecl>(GetDecl(Record[Idx++])));
+      Protos.push_back(ReadDeclAs<ObjCProtocolDecl>(*Loc.F, Record, Idx));
     return Context->getObjCObjectType(Base, Protos.data(), NumProtos);
   }
 
@@ -3523,7 +3511,8 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
   }
 
   case TYPE_INJECTED_CLASS_NAME: {
-    CXXRecordDecl *D = cast<CXXRecordDecl>(GetDecl(Record[0]));
+    unsigned Idx = 0;
+    CXXRecordDecl *D = ReadDeclAs<CXXRecordDecl>(*Loc.F, Record, Idx);
     QualType TST = GetType(Record[1]); // probably derivable
     // FIXME: ASTContext::getInjectedClassNameType is not currently suitable
     // for AST reading, too much interdependencies.
@@ -3536,15 +3525,15 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
     unsigned Depth = Record[Idx++];
     unsigned Index = Record[Idx++];
     bool Pack = Record[Idx++];
-    TemplateTypeParmDecl *D =
-      cast_or_null<TemplateTypeParmDecl>(GetDecl(Record[Idx++]));
+    TemplateTypeParmDecl *D
+      = ReadDeclAs<TemplateTypeParmDecl>(*Loc.F, Record, Idx);
     return Context->getTemplateTypeParmType(Depth, Index, Pack, D);
   }
 
   case TYPE_DEPENDENT_NAME: {
     unsigned Idx = 0;
     ElaboratedTypeKeyword Keyword = (ElaboratedTypeKeyword)Record[Idx++];
-    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(Record, Idx);
+    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(*Loc.F, Record, Idx);
     const IdentifierInfo *Name = this->GetIdentifierInfo(Record, Idx);
     QualType Canon = GetType(Record[Idx++]);
     if (!Canon.isNull())
@@ -3555,7 +3544,7 @@ QualType ASTReader::ReadTypeRecord(unsigned Index) {
   case TYPE_DEPENDENT_TEMPLATE_SPECIALIZATION: {
     unsigned Idx = 0;
     ElaboratedTypeKeyword Keyword = (ElaboratedTypeKeyword)Record[Idx++];
-    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(Record, Idx);
+    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(*Loc.F, Record, Idx);
     const IdentifierInfo *Name = this->GetIdentifierInfo(Record, Idx);
     unsigned NumArgs = Record[Idx++];
     llvm::SmallVector<TemplateArgument, 8> Args;
@@ -3617,6 +3606,11 @@ class clang::TypeLocReader : public TypeLocVisitor<TypeLocReader> {
     return Reader.ReadSourceLocation(F, R, I);
   }
 
+  template<typename T>
+  T *ReadDeclAs(const ASTReader::RecordData &Record, unsigned &Idx) {
+    return Reader.ReadDeclAs<T>(F, Record, Idx);
+  }
+  
 public:
   TypeLocReader(ASTReader &Reader, ASTReader::PerFileData &F,
                 const ASTReader::RecordData &Record, unsigned &Idx)
@@ -3702,7 +3696,7 @@ void TypeLocReader::VisitFunctionTypeLoc(FunctionTypeLoc TL) {
   TL.setLocalRangeEnd(ReadSourceLocation(Record, Idx));
   TL.setTrailingReturn(Record[Idx++]);
   for (unsigned i = 0, e = TL.getNumArgs(); i != e; ++i) {
-    TL.setArg(i, cast_or_null<ParmVarDecl>(Reader.GetDecl(Record[Idx++])));
+    TL.setArg(i, ReadDeclAs<ParmVarDecl>(Record, Idx));
   }
 }
 void TypeLocReader::VisitFunctionProtoTypeLoc(FunctionProtoTypeLoc TL) {
@@ -4048,6 +4042,12 @@ TranslationUnitDecl *ASTReader::GetTranslationUnitDecl() {
   return cast<TranslationUnitDecl>(DeclsLoaded[0]);
 }
 
+serialization::DeclID 
+ASTReader::getGlobalDeclID(PerFileData &F, unsigned LocalID) const {
+  // FIXME: Perform local -> global remapping for declarations.
+  return LocalID;
+}
+
 Decl *ASTReader::GetDecl(DeclID ID) {
   if (ID == 0)
     return 0;
@@ -4067,6 +4067,17 @@ Decl *ASTReader::GetDecl(DeclID ID) {
   return DeclsLoaded[Index];
 }
 
+serialization::DeclID ASTReader::ReadDeclID(PerFileData &F, 
+                                            const RecordData &Record,
+                                            unsigned &Idx) {
+  if (Idx >= Record.size()) {
+    Error("Corrupted AST file");
+    return 0;
+  }
+  
+  return getGlobalDeclID(F, Record[Idx++]);
+}
+
 /// \brief Resolve the offset of a statement into a statement.
 ///
 /// This operation will read a new statement from the external
@@ -4109,7 +4120,9 @@ ExternalLoadResult ASTReader::FindExternalLexicalDecls(const DeclContext *DC,
                               *IDE = ID + I->NumLexicalDecls; ID != IDE; ++ID) {
       if (isKindWeWant && !isKindWeWant((Decl::Kind)ID->first))
         continue;
-
+      
+      // FIXME: Modules need to know whether this is already mapped to a 
+      // global ID or not.
       Decl *D = GetDecl(ID->second);
       assert(D && "Null decl in lexical decls");
       Decls.push_back(D);
@@ -4145,6 +4158,8 @@ ASTReader::FindExternalVisibleDeclsByName(const DeclContext *DC,
     if (Pos == LookupTable->end())
       continue;
 
+    // FIXME: Modules need to know whether this is already mapped to a 
+    // global ID or not.
     ASTDeclContextNameLookupTrait::data_type Data = *Pos;
     for (; Data.first != Data.second; ++Data.first)
       Decls.push_back(cast<NamedDecl>(GetDecl(*Data.first)));
@@ -4179,6 +4194,8 @@ void ASTReader::MaterializeVisibleDecls(const DeclContext *DC) {
           = *ItemI;
       ASTDeclContextNameLookupTrait::data_type Data = Val.second;
       Decls.clear();
+      // FIXME: Modules need to know whether this is already mapped to a 
+      // global ID or not.
       for (; Data.first != Data.second; ++Data.first)
         Decls.push_back(cast<NamedDecl>(GetDecl(*Data.first)));
       MaterializeVisibleDeclsForName(DC, Val.first, Decls);
@@ -4647,6 +4664,7 @@ ASTReader::SetGloballyVisibleDecls(IdentifierInfo *II,
   }
 
   for (unsigned I = 0, N = DeclIDs.size(); I != N; ++I) {
+    // FIXME: Are these IDs local or global? It's not clear!
     NamedDecl *D = cast<NamedDecl>(GetDecl(DeclIDs[I]));
     if (SemaObj) {
       if (SemaObj->TUScope) {
@@ -4717,8 +4735,8 @@ Selector ASTReader::DecodeSelector(unsigned ID) {
     // Load this selector from the selector table.
     GlobalSelectorMapType::iterator I = GlobalSelectorMap.find(ID);
     assert(I != GlobalSelectorMap.end() && "Corrupted global selector map");
-    ASTSelectorLookupTrait Trait(*this);
     PerFileData &F = *I->second.first;
+    ASTSelectorLookupTrait Trait(*this, F);
     unsigned Idx = ID - 1 + I->second.second;
     SelectorsLoaded[ID - 1] =
       Trait.ReadKey(F.SelectorLookupTableData + F.SelectorOffsets[Idx], 0);
@@ -4838,26 +4856,26 @@ ASTReader::ReadTemplateName(PerFileData &F, const RecordData &Record,
   TemplateName::NameKind Kind = (TemplateName::NameKind)Record[Idx++];
   switch (Kind) {
   case TemplateName::Template:
-    return TemplateName(cast_or_null<TemplateDecl>(GetDecl(Record[Idx++])));
+      return TemplateName(ReadDeclAs<TemplateDecl>(F, Record, Idx));
 
   case TemplateName::OverloadedTemplate: {
     unsigned size = Record[Idx++];
     UnresolvedSet<8> Decls;
     while (size--)
-      Decls.addDecl(cast<NamedDecl>(GetDecl(Record[Idx++])));
+      Decls.addDecl(ReadDeclAs<NamedDecl>(F, Record, Idx));
 
     return Context->getOverloadedTemplateName(Decls.begin(), Decls.end());
   }
 
   case TemplateName::QualifiedTemplate: {
-    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(Record, Idx);
+    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(F, Record, Idx);
     bool hasTemplKeyword = Record[Idx++];
-    TemplateDecl *Template = cast<TemplateDecl>(GetDecl(Record[Idx++]));
+    TemplateDecl *Template = ReadDeclAs<TemplateDecl>(F, Record, Idx);
     return Context->getQualifiedTemplateName(NNS, hasTemplKeyword, Template);
   }
 
   case TemplateName::DependentTemplate: {
-    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(Record, Idx);
+    NestedNameSpecifier *NNS = ReadNestedNameSpecifier(F, Record, Idx);
     if (Record[Idx++])  // isIdentifier
       return Context->getDependentTemplateName(NNS,
                                                GetIdentifierInfo(Record, Idx));
@@ -4867,7 +4885,7 @@ ASTReader::ReadTemplateName(PerFileData &F, const RecordData &Record,
 
   case TemplateName::SubstTemplateTemplateParm: {
     TemplateTemplateParmDecl *param
-      = cast_or_null<TemplateTemplateParmDecl>(GetDecl(Record[Idx++]));
+      = ReadDeclAs<TemplateTemplateParmDecl>(F, Record, Idx);
     if (!param) return TemplateName();
     TemplateName replacement = ReadTemplateName(F, Record, Idx);
     return Context->getSubstTemplateTemplateParm(param, replacement);
@@ -4875,7 +4893,7 @@ ASTReader::ReadTemplateName(PerFileData &F, const RecordData &Record,
       
   case TemplateName::SubstTemplateTemplateParmPack: {
     TemplateTemplateParmDecl *Param 
-      = cast_or_null<TemplateTemplateParmDecl>(GetDecl(Record[Idx++]));
+      = ReadDeclAs<TemplateTemplateParmDecl>(F, Record, Idx);
     if (!Param)
       return TemplateName();
     
@@ -4901,7 +4919,7 @@ ASTReader::ReadTemplateArgument(PerFileData &F,
   case TemplateArgument::Type:
     return TemplateArgument(GetType(Record[Idx++]));
   case TemplateArgument::Declaration:
-    return TemplateArgument(GetDecl(Record[Idx++]));
+    return TemplateArgument(ReadDecl(F, Record, Idx));
   case TemplateArgument::Integral: {
     llvm::APSInt Value = ReadAPSInt(Record, Idx);
     QualType T = GetType(Record[Idx++]);
@@ -4942,7 +4960,7 @@ ASTReader::ReadTemplateParameterList(PerFileData &F,
   llvm::SmallVector<NamedDecl *, 16> Params;
   Params.reserve(NumParams);
   while (NumParams--)
-    Params.push_back(cast<NamedDecl>(GetDecl(Record[Idx++])));
+    Params.push_back(ReadDeclAs<NamedDecl>(F, Record, Idx));
 
   TemplateParameterList* TemplateParams =
     TemplateParameterList::Create(*Context, TemplateLoc, LAngleLoc,
@@ -4962,11 +4980,11 @@ ReadTemplateArgumentList(llvm::SmallVector<TemplateArgument, 8> &TemplArgs,
 }
 
 /// \brief Read a UnresolvedSet structure.
-void ASTReader::ReadUnresolvedSet(UnresolvedSetImpl &Set,
+void ASTReader::ReadUnresolvedSet(PerFileData &F, UnresolvedSetImpl &Set,
                                   const RecordData &Record, unsigned &Idx) {
   unsigned NumDecls = Record[Idx++];
   while (NumDecls--) {
-    NamedDecl *D = cast<NamedDecl>(GetDecl(Record[Idx++]));
+    NamedDecl *D = ReadDeclAs<NamedDecl>(F, Record, Idx);
     AccessSpecifier AS = (AccessSpecifier)Record[Idx++];
     Set.addDecl(D, AS);
   }
@@ -5013,15 +5031,15 @@ ASTReader::ReadCXXCtorInitializers(PerFileData &F, const RecordData &Record,
         break;
 
        case CTOR_INITIALIZER_DELEGATING:
-        Target = cast<CXXConstructorDecl>(GetDecl(Record[Idx++]));
+        Target = ReadDeclAs<CXXConstructorDecl>(F, Record, Idx);
         break;
 
        case CTOR_INITIALIZER_MEMBER:
-        Member = cast<FieldDecl>(GetDecl(Record[Idx++]));
+        Member = ReadDeclAs<FieldDecl>(F, Record, Idx);
         break;
 
        case CTOR_INITIALIZER_INDIRECT_MEMBER:
-        IndirectMember = cast<IndirectFieldDecl>(GetDecl(Record[Idx++]));
+        IndirectMember = ReadDeclAs<IndirectFieldDecl>(F, Record, Idx);
         break;
       }
 
@@ -5038,7 +5056,7 @@ ASTReader::ReadCXXCtorInitializers(PerFileData &F, const RecordData &Record,
         SourceOrderOrNumArrayIndices = Record[Idx++];
         Indices.reserve(SourceOrderOrNumArrayIndices);
         for (unsigned i=0; i != SourceOrderOrNumArrayIndices; ++i)
-          Indices.push_back(cast<VarDecl>(GetDecl(Record[Idx++])));
+          Indices.push_back(ReadDeclAs<VarDecl>(F, Record, Idx));
       }
 
       CXXCtorInitializer *BOMInit;
@@ -5073,7 +5091,8 @@ ASTReader::ReadCXXCtorInitializers(PerFileData &F, const RecordData &Record,
 }
 
 NestedNameSpecifier *
-ASTReader::ReadNestedNameSpecifier(const RecordData &Record, unsigned &Idx) {
+ASTReader::ReadNestedNameSpecifier(PerFileData &F,
+                                   const RecordData &Record, unsigned &Idx) {
   unsigned N = Record[Idx++];
   NestedNameSpecifier *NNS = 0, *Prev = 0;
   for (unsigned I = 0; I != N; ++I) {
@@ -5087,14 +5106,13 @@ ASTReader::ReadNestedNameSpecifier(const RecordData &Record, unsigned &Idx) {
     }
 
     case NestedNameSpecifier::Namespace: {
-      NamespaceDecl *NS = cast<NamespaceDecl>(GetDecl(Record[Idx++]));
+      NamespaceDecl *NS = ReadDeclAs<NamespaceDecl>(F, Record, Idx);
       NNS = NestedNameSpecifier::Create(*Context, Prev, NS);
       break;
     }
 
     case NestedNameSpecifier::NamespaceAlias: {
-      NamespaceAliasDecl *Alias
-        = cast<NamespaceAliasDecl>(GetDecl(Record[Idx++]));
+      NamespaceAliasDecl *Alias =ReadDeclAs<NamespaceAliasDecl>(F, Record, Idx);
       NNS = NestedNameSpecifier::Create(*Context, Prev, Alias);
       break;
     }
@@ -5138,15 +5156,14 @@ ASTReader::ReadNestedNameSpecifierLoc(PerFileData &F, const RecordData &Record,
     }
 
     case NestedNameSpecifier::Namespace: {
-      NamespaceDecl *NS = cast<NamespaceDecl>(GetDecl(Record[Idx++]));
+      NamespaceDecl *NS = ReadDeclAs<NamespaceDecl>(F, Record, Idx);
       SourceRange Range = ReadSourceRange(F, Record, Idx);
       Builder.Extend(*Context, NS, Range.getBegin(), Range.getEnd());
       break;
     }
 
     case NestedNameSpecifier::NamespaceAlias: {
-      NamespaceAliasDecl *Alias
-        = cast<NamespaceAliasDecl>(GetDecl(Record[Idx++]));
+      NamespaceAliasDecl *Alias =ReadDeclAs<NamespaceAliasDecl>(F, Record, Idx);
       SourceRange Range = ReadSourceRange(F, Record, Idx);
       Builder.Extend(*Context, Alias, Range.getBegin(), Range.getEnd());
       break;
@@ -5226,9 +5243,10 @@ VersionTuple ASTReader::ReadVersionTuple(const RecordData &Record,
   return VersionTuple(Major, Minor - 1, Subminor - 1);
 }
 
-CXXTemporary *ASTReader::ReadCXXTemporary(const RecordData &Record,
+CXXTemporary *ASTReader::ReadCXXTemporary(PerFileData &F, 
+                                          const RecordData &Record,
                                           unsigned &Idx) {
-  CXXDestructorDecl *Decl = cast<CXXDestructorDecl>(GetDecl(Record[Idx++]));
+  CXXDestructorDecl *Decl = ReadDeclAs<CXXDestructorDecl>(F, Record, Idx);
   return CXXTemporary::Create(*Context, Decl);
 }
 
diff --git a/clang/lib/Serialization/ASTReaderDecl.cpp b/clang/lib/Serialization/ASTReaderDecl.cpp
index 4f55d4625d47..8132ed9a5f02 100644
--- a/clang/lib/Serialization/ASTReaderDecl.cpp
+++ b/clang/lib/Serialization/ASTReaderDecl.cpp
@@ -43,23 +43,42 @@ namespace clang {
     DeclID LexicalDeclContextIDForTemplateParmDecl;
 
     uint64_t GetCurrentCursorOffset();
+    
     SourceLocation ReadSourceLocation(const RecordData &R, unsigned &I) {
       return Reader.ReadSourceLocation(F, R, I);
     }
+    
     SourceRange ReadSourceRange(const RecordData &R, unsigned &I) {
       return Reader.ReadSourceRange(F, R, I);
     }
+    
     TypeSourceInfo *GetTypeSourceInfo(const RecordData &R, unsigned &I) {
       return Reader.GetTypeSourceInfo(F, R, I);
     }
+    
+    serialization::DeclID ReadDeclID(const RecordData &R, unsigned &I) {
+      return Reader.ReadDeclID(F, R, I);
+    }
+    
+    Decl *ReadDecl(const RecordData &R, unsigned &I) {
+      return Reader.ReadDecl(F, R, I);
+    }
+
+    template<typename T>
+    T *ReadDeclAs(const RecordData &R, unsigned &I) {
+      return Reader.ReadDeclAs<T>(F, R, I);
+    }
+
     void ReadQualifierInfo(QualifierInfo &Info,
                            const RecordData &R, unsigned &I) {
       Reader.ReadQualifierInfo(F, Info, R, I);
     }
+    
     void ReadDeclarationNameLoc(DeclarationNameLoc &DNLoc, DeclarationName Name,
                                 const RecordData &R, unsigned &I) {
       Reader.ReadDeclarationNameLoc(F, DNLoc, Name, R, I);
     }
+    
     void ReadDeclarationNameInfo(DeclarationNameInfo &NameInfo,
                                 const RecordData &R, unsigned &I) {
       Reader.ReadDeclarationNameInfo(F, NameInfo, R, I);
@@ -211,13 +230,12 @@ void ASTDeclReader::VisitDecl(Decl *D) {
     // parameter immediately, because the template parameter might be
     // used in the formulation of its DeclContext. Use the translation
     // unit DeclContext as a placeholder.
-    DeclContextIDForTemplateParmDecl = Record[Idx++];
-    LexicalDeclContextIDForTemplateParmDecl = Record[Idx++];
+    DeclContextIDForTemplateParmDecl = ReadDeclID(Record, Idx);
+    LexicalDeclContextIDForTemplateParmDecl = ReadDeclID(Record, Idx);
     D->setDeclContext(Reader.getContext()->getTranslationUnitDecl()); 
   } else {
-    D->setDeclContext(cast_or_null<DeclContext>(Reader.GetDecl(Record[Idx++])));
-    D->setLexicalDeclContext(
-                     cast_or_null<DeclContext>(Reader.GetDecl(Record[Idx++])));
+    D->setDeclContext(ReadDeclAs<DeclContext>(Record, Idx));
+    D->setLexicalDeclContext(ReadDeclAs<DeclContext>(Record, Idx));
   }
   D->setLocation(ReadSourceLocation(Record, Idx));
   D->setInvalidDecl(Record[Idx++]);
@@ -235,8 +253,7 @@ void ASTDeclReader::VisitDecl(Decl *D) {
 
 void ASTDeclReader::VisitTranslationUnitDecl(TranslationUnitDecl *TU) {
   VisitDecl(TU);
-  TU->setAnonymousNamespace(
-                    cast_or_null<NamespaceDecl>(Reader.GetDecl(Record[Idx++])));
+  TU->setAnonymousNamespace(ReadDeclAs<NamespaceDecl>(Record, Idx));
 }
 
 void ASTDeclReader::VisitNamedDecl(NamedDecl *ND) {
@@ -274,8 +291,7 @@ void ASTDeclReader::VisitTagDecl(TagDecl *TD) {
     ReadQualifierInfo(*Info, Record, Idx);
     TD->TypedefNameDeclOrQualifier = Info;
   } else
-    TD->setTypedefNameForAnonDecl(
-                  cast_or_null<TypedefNameDecl>(Reader.GetDecl(Record[Idx++])));
+    TD->setTypedefNameForAnonDecl(ReadDeclAs<TypedefNameDecl>(Record, Idx));
 }
 
 void ASTDeclReader::VisitEnumDecl(EnumDecl *ED) {
@@ -290,8 +306,7 @@ void ASTDeclReader::VisitEnumDecl(EnumDecl *ED) {
   ED->IsScoped = Record[Idx++];
   ED->IsScopedUsingClassTag = Record[Idx++];
   ED->IsFixed = Record[Idx++];
-  ED->setInstantiationOfMemberEnum(
-                         cast_or_null<EnumDecl>(Reader.GetDecl(Record[Idx++])));
+  ED->setInstantiationOfMemberEnum(ReadDeclAs<EnumDecl>(Record, Idx));
 }
 
 void ASTDeclReader::VisitRecordDecl(RecordDecl *RD) {
@@ -336,11 +351,11 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
   case FunctionDecl::TK_NonTemplate:
     break;
   case FunctionDecl::TK_FunctionTemplate:
-    FD->setDescribedFunctionTemplate(
-                     cast<FunctionTemplateDecl>(Reader.GetDecl(Record[Idx++])));
+    FD->setDescribedFunctionTemplate(ReadDeclAs<FunctionTemplateDecl>(Record, 
+                                                                      Idx));
     break;
   case FunctionDecl::TK_MemberSpecialization: {
-    FunctionDecl *InstFD = cast<FunctionDecl>(Reader.GetDecl(Record[Idx++]));
+    FunctionDecl *InstFD = ReadDeclAs<FunctionDecl>(Record, Idx);
     TemplateSpecializationKind TSK = (TemplateSpecializationKind)Record[Idx++];
     SourceLocation POI = ReadSourceLocation(Record, Idx);
     FD->setInstantiationOfMemberFunction(*Reader.getContext(), InstFD, TSK);
@@ -348,8 +363,8 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
     break;
   }
   case FunctionDecl::TK_FunctionTemplateSpecialization: {
-    FunctionTemplateDecl *Template
-      = cast<FunctionTemplateDecl>(Reader.GetDecl(Record[Idx++]));
+    FunctionTemplateDecl *Template = ReadDeclAs<FunctionTemplateDecl>(Record, 
+                                                                      Idx);
     TemplateSpecializationKind TSK = (TemplateSpecializationKind)Record[Idx++];
     
     // Template arguments.
@@ -389,7 +404,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
       // The template that contains the specializations set. It's not safe to
       // use getCanonicalDecl on Template since it may still be initializing.
       FunctionTemplateDecl *CanonTemplate
-        = cast<FunctionTemplateDecl>(Reader.GetDecl(Record[Idx++]));
+        = ReadDeclAs<FunctionTemplateDecl>(Record, Idx);
       // Get the InsertPos by FindNodeOrInsertPos() instead of calling
       // InsertNode(FTInfo) directly to avoid the getASTContext() call in
       // FunctionTemplateSpecializationInfo's Profile().
@@ -410,7 +425,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
     UnresolvedSet<8> TemplDecls;
     unsigned NumTemplates = Record[Idx++];
     while (NumTemplates--)
-      TemplDecls.addDecl(cast<NamedDecl>(Reader.GetDecl(Record[Idx++])));
+      TemplDecls.addDecl(ReadDeclAs<NamedDecl>(Record, Idx));
     
     // Templates args.
     TemplateArgumentListInfo TemplArgs;
@@ -449,7 +464,7 @@ void ASTDeclReader::VisitFunctionDecl(FunctionDecl *FD) {
   llvm::SmallVector<ParmVarDecl *, 16> Params;
   Params.reserve(NumParams);
   for (unsigned I = 0; I != NumParams; ++I)
-    Params.push_back(cast<ParmVarDecl>(Reader.GetDecl(Record[Idx++])));
+    Params.push_back(ReadDeclAs<ParmVarDecl>(Record, Idx));
   FD->setParams(*Reader.getContext(), Params.data(), NumParams);
 }
 
@@ -459,8 +474,8 @@ void ASTDeclReader::VisitObjCMethodDecl(ObjCMethodDecl *MD) {
     // In practice, this won't be executed (since method definitions
     // don't occur in header files).
     MD->setBody(Reader.ReadStmt(F));
-    MD->setSelfDecl(cast<ImplicitParamDecl>(Reader.GetDecl(Record[Idx++])));
-    MD->setCmdDecl(cast<ImplicitParamDecl>(Reader.GetDecl(Record[Idx++])));
+    MD->setSelfDecl(ReadDeclAs<ImplicitParamDecl>(Record, Idx));
+    MD->setCmdDecl(ReadDeclAs<ImplicitParamDecl>(Record, Idx));
   }
   MD->setInstanceMethod(Record[Idx++]);
   MD->setVariadic(Record[Idx++]);
@@ -477,7 +492,7 @@ void ASTDeclReader::VisitObjCMethodDecl(ObjCMethodDecl *MD) {
   llvm::SmallVector<ParmVarDecl *, 16> Params;
   Params.reserve(NumParams);
   for (unsigned I = 0; I != NumParams; ++I)
-    Params.push_back(cast<ParmVarDecl>(Reader.GetDecl(Record[Idx++])));
+    Params.push_back(ReadDeclAs<ParmVarDecl>(Record, Idx));
   MD->setMethodParams(*Reader.getContext(), Params.data(), NumParams,
                       NumParams);
 }
@@ -492,15 +507,14 @@ void ASTDeclReader::VisitObjCContainerDecl(ObjCContainerDecl *CD) {
 void ASTDeclReader::VisitObjCInterfaceDecl(ObjCInterfaceDecl *ID) {
   VisitObjCContainerDecl(ID);
   ID->setTypeForDecl(Reader.GetType(Record[Idx++]).getTypePtrOrNull());
-  ID->setSuperClass(cast_or_null<ObjCInterfaceDecl>
-                       (Reader.GetDecl(Record[Idx++])));
+  ID->setSuperClass(ReadDeclAs<ObjCInterfaceDecl>(Record, Idx));
   
   // Read the directly referenced protocols and their SourceLocations.
   unsigned NumProtocols = Record[Idx++];
   llvm::SmallVector<ObjCProtocolDecl *, 16> Protocols;
   Protocols.reserve(NumProtocols);
   for (unsigned I = 0; I != NumProtocols; ++I)
-    Protocols.push_back(cast<ObjCProtocolDecl>(Reader.GetDecl(Record[Idx++])));
+    Protocols.push_back(ReadDeclAs<ObjCProtocolDecl>(Record, Idx));
   llvm::SmallVector<SourceLocation, 16> ProtoLocs;
   ProtoLocs.reserve(NumProtocols);
   for (unsigned I = 0; I != NumProtocols; ++I)
@@ -513,7 +527,7 @@ void ASTDeclReader::VisitObjCInterfaceDecl(ObjCInterfaceDecl *ID) {
   Protocols.clear();
   Protocols.reserve(NumProtocols);
   for (unsigned I = 0; I != NumProtocols; ++I)
-    Protocols.push_back(cast<ObjCProtocolDecl>(Reader.GetDecl(Record[Idx++])));
+    Protocols.push_back(ReadDeclAs<ObjCProtocolDecl>(Record, Idx));
   ID->AllReferencedProtocols.set(Protocols.data(), NumProtocols,
                                  *Reader.getContext());
   
@@ -522,9 +536,9 @@ void ASTDeclReader::VisitObjCInterfaceDecl(ObjCInterfaceDecl *ID) {
   llvm::SmallVector<ObjCIvarDecl *, 16> IVars;
   IVars.reserve(NumIvars);
   for (unsigned I = 0; I != NumIvars; ++I)
-    IVars.push_back(cast<ObjCIvarDecl>(Reader.GetDecl(Record[Idx++])));
-  ID->setCategoryList(
-               cast_or_null<ObjCCategoryDecl>(Reader.GetDecl(Record[Idx++])));
+    IVars.push_back(ReadDeclAs<ObjCIvarDecl>(Record, Idx));
+  ID->setCategoryList(ReadDeclAs<ObjCCategoryDecl>(Record, Idx));
+  
   // We will rebuild this list lazily.
   ID->setIvarList(0);
   ID->setForwardDecl(Record[Idx++]);
@@ -551,7 +565,7 @@ void ASTDeclReader::VisitObjCProtocolDecl(ObjCProtocolDecl *PD) {
   llvm::SmallVector<ObjCProtocolDecl *, 16> ProtoRefs;
   ProtoRefs.reserve(NumProtoRefs);
   for (unsigned I = 0; I != NumProtoRefs; ++I)
-    ProtoRefs.push_back(cast<ObjCProtocolDecl>(Reader.GetDecl(Record[Idx++])));
+    ProtoRefs.push_back(ReadDeclAs<ObjCProtocolDecl>(Record, Idx));
   llvm::SmallVector<SourceLocation, 16> ProtoLocs;
   ProtoLocs.reserve(NumProtoRefs);
   for (unsigned I = 0; I != NumProtoRefs; ++I)
@@ -570,7 +584,7 @@ void ASTDeclReader::VisitObjCClassDecl(ObjCClassDecl *CD) {
   llvm::SmallVector<ObjCInterfaceDecl *, 16> ClassRefs;
   ClassRefs.reserve(NumClassRefs);
   for (unsigned I = 0; I != NumClassRefs; ++I)
-    ClassRefs.push_back(cast<ObjCInterfaceDecl>(Reader.GetDecl(Record[Idx++])));
+    ClassRefs.push_back(ReadDeclAs<ObjCInterfaceDecl>(Record, Idx));
   llvm::SmallVector<SourceLocation, 16> SLocs;
   SLocs.reserve(NumClassRefs);
   for (unsigned I = 0; I != NumClassRefs; ++I)
@@ -585,7 +599,7 @@ void ASTDeclReader::VisitObjCForwardProtocolDecl(ObjCForwardProtocolDecl *FPD) {
   llvm::SmallVector<ObjCProtocolDecl *, 16> ProtoRefs;
   ProtoRefs.reserve(NumProtoRefs);
   for (unsigned I = 0; I != NumProtoRefs; ++I)
-    ProtoRefs.push_back(cast<ObjCProtocolDecl>(Reader.GetDecl(Record[Idx++])));
+    ProtoRefs.push_back(ReadDeclAs<ObjCProtocolDecl>(Record, Idx));
   llvm::SmallVector<SourceLocation, 16> ProtoLocs;
   ProtoLocs.reserve(NumProtoRefs);
   for (unsigned I = 0; I != NumProtoRefs; ++I)
@@ -596,19 +610,19 @@ void ASTDeclReader::VisitObjCForwardProtocolDecl(ObjCForwardProtocolDecl *FPD) {
 
 void ASTDeclReader::VisitObjCCategoryDecl(ObjCCategoryDecl *CD) {
   VisitObjCContainerDecl(CD);
-  CD->setClassInterface(cast<ObjCInterfaceDecl>(Reader.GetDecl(Record[Idx++])));
+  CD->setClassInterface(ReadDeclAs<ObjCInterfaceDecl>(Record, Idx));
   unsigned NumProtoRefs = Record[Idx++];
   llvm::SmallVector<ObjCProtocolDecl *, 16> ProtoRefs;
   ProtoRefs.reserve(NumProtoRefs);
   for (unsigned I = 0; I != NumProtoRefs; ++I)
-    ProtoRefs.push_back(cast<ObjCProtocolDecl>(Reader.GetDecl(Record[Idx++])));
+    ProtoRefs.push_back(ReadDeclAs<ObjCProtocolDecl>(Record, Idx));
   llvm::SmallVector<SourceLocation, 16> ProtoLocs;
   ProtoLocs.reserve(NumProtoRefs);
   for (unsigned I = 0; I != NumProtoRefs; ++I)
     ProtoLocs.push_back(ReadSourceLocation(Record, Idx));
   CD->setProtocolList(ProtoRefs.data(), NumProtoRefs, ProtoLocs.data(),
                       *Reader.getContext());
-  CD->setNextClassCategory(cast_or_null<ObjCCategoryDecl>(Reader.GetDecl(Record[Idx++])));
+  CD->setNextClassCategory(ReadDeclAs<ObjCCategoryDecl>(Record, Idx));
   CD->setHasSynthBitfield(Record[Idx++]);
   CD->setAtLoc(ReadSourceLocation(Record, Idx));
   CD->setCategoryNameLoc(ReadSourceLocation(Record, Idx));
@@ -616,7 +630,7 @@ void ASTDeclReader::VisitObjCCategoryDecl(ObjCCategoryDecl *CD) {
 
 void ASTDeclReader::VisitObjCCompatibleAliasDecl(ObjCCompatibleAliasDecl *CAD) {
   VisitNamedDecl(CAD);
-  CAD->setClassInterface(cast<ObjCInterfaceDecl>(Reader.GetDecl(Record[Idx++])));
+  CAD->setClassInterface(ReadDeclAs<ObjCInterfaceDecl>(Record, Idx));
 }
 
 void ASTDeclReader::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
@@ -633,18 +647,14 @@ void ASTDeclReader::VisitObjCPropertyDecl(ObjCPropertyDecl *D) {
                             (ObjCPropertyDecl::PropertyControl)Record[Idx++]);
   D->setGetterName(Reader.ReadDeclarationName(Record, Idx).getObjCSelector());
   D->setSetterName(Reader.ReadDeclarationName(Record, Idx).getObjCSelector());
-  D->setGetterMethodDecl(
-                 cast_or_null<ObjCMethodDecl>(Reader.GetDecl(Record[Idx++])));
-  D->setSetterMethodDecl(
-                 cast_or_null<ObjCMethodDecl>(Reader.GetDecl(Record[Idx++])));
-  D->setPropertyIvarDecl(
-                   cast_or_null<ObjCIvarDecl>(Reader.GetDecl(Record[Idx++])));
+  D->setGetterMethodDecl(ReadDeclAs<ObjCMethodDecl>(Record, Idx));
+  D->setSetterMethodDecl(ReadDeclAs<ObjCMethodDecl>(Record, Idx));
+  D->setPropertyIvarDecl(ReadDeclAs<ObjCIvarDecl>(Record, Idx));
 }
 
 void ASTDeclReader::VisitObjCImplDecl(ObjCImplDecl *D) {
   VisitObjCContainerDecl(D);
-  D->setClassInterface(
-              cast_or_null<ObjCInterfaceDecl>(Reader.GetDecl(Record[Idx++])));
+  D->setClassInterface(ReadDeclAs<ObjCInterfaceDecl>(Record, Idx));
 }
 
 void ASTDeclReader::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
@@ -654,8 +664,7 @@ void ASTDeclReader::VisitObjCCategoryImplDecl(ObjCCategoryImplDecl *D) {
 
 void ASTDeclReader::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
   VisitObjCImplDecl(D);
-  D->setSuperClass(
-              cast_or_null<ObjCInterfaceDecl>(Reader.GetDecl(Record[Idx++])));
+  D->setSuperClass(ReadDeclAs<ObjCInterfaceDecl>(Record, Idx));
   llvm::tie(D->IvarInitializers, D->NumIvarInitializers)
       = Reader.ReadCXXCtorInitializers(F, Record, Idx);
   D->setHasSynthBitfield(Record[Idx++]);
@@ -665,10 +674,8 @@ void ASTDeclReader::VisitObjCImplementationDecl(ObjCImplementationDecl *D) {
 void ASTDeclReader::VisitObjCPropertyImplDecl(ObjCPropertyImplDecl *D) {
   VisitDecl(D);
   D->setAtLoc(ReadSourceLocation(Record, Idx));
-  D->setPropertyDecl(
-               cast_or_null<ObjCPropertyDecl>(Reader.GetDecl(Record[Idx++])));
-  D->PropertyIvarDecl = 
-                   cast_or_null<ObjCIvarDecl>(Reader.GetDecl(Record[Idx++]));
+  D->setPropertyDecl(ReadDeclAs<ObjCPropertyDecl>(Record, Idx));
+  D->PropertyIvarDecl = ReadDeclAs<ObjCIvarDecl>(Record, Idx);
   D->IvarLoc = ReadSourceLocation(Record, Idx);
   D->setGetterCXXConstructor(Reader.ReadExpr(F));
   D->setSetterCXXAssignment(Reader.ReadExpr(F));
@@ -683,8 +690,7 @@ void ASTDeclReader::VisitFieldDecl(FieldDecl *FD) {
   else if (BitWidthOrInitializer == 2)
     FD->setInClassInitializer(Reader.ReadExpr(F));
   if (!FD->getDeclName()) {
-    FieldDecl *Tmpl = cast_or_null<FieldDecl>(Reader.GetDecl(Record[Idx++]));
-    if (Tmpl)
+    if (FieldDecl *Tmpl = ReadDeclAs<FieldDecl>(Record, Idx))
       Reader.getContext()->setInstantiatedFromUnnamedFieldDecl(FD, Tmpl);
   }
 }
@@ -697,7 +703,7 @@ void ASTDeclReader::VisitIndirectFieldDecl(IndirectFieldDecl *FD) {
   FD->Chaining = new (*Reader.getContext())NamedDecl*[FD->ChainingSize];
 
   for (unsigned I = 0; I != FD->ChainingSize; ++I)
-    FD->Chaining[I] = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+    FD->Chaining[I] = ReadDeclAs<NamedDecl>(Record, Idx);
 }
 
 void ASTDeclReader::VisitVarDecl(VarDecl *VD) {
@@ -715,7 +721,7 @@ void ASTDeclReader::VisitVarDecl(VarDecl *VD) {
     VD->setInit(Reader.ReadExpr(F));
 
   if (Record[Idx++]) { // HasMemberSpecializationInfo.
-    VarDecl *Tmpl = cast<VarDecl>(Reader.GetDecl(Record[Idx++]));
+    VarDecl *Tmpl = ReadDeclAs<VarDecl>(Record, Idx);
     TemplateSpecializationKind TSK = (TemplateSpecializationKind)Record[Idx++];
     SourceLocation POI = ReadSourceLocation(Record, Idx);
     Reader.getContext()->setInstantiatedFromStaticDataMember(VD, Tmpl, TSK,POI);
@@ -759,7 +765,7 @@ void ASTDeclReader::VisitBlockDecl(BlockDecl *BD) {
   llvm::SmallVector<ParmVarDecl *, 16> Params;
   Params.reserve(NumParams);
   for (unsigned I = 0; I != NumParams; ++I)
-    Params.push_back(cast<ParmVarDecl>(Reader.GetDecl(Record[Idx++])));
+    Params.push_back(ReadDeclAs<ParmVarDecl>(Record, Idx));
   BD->setParams(Params.data(), NumParams);
 
   bool capturesCXXThis = Record[Idx++];
@@ -767,7 +773,7 @@ void ASTDeclReader::VisitBlockDecl(BlockDecl *BD) {
   llvm::SmallVector<BlockDecl::Capture, 16> captures;
   captures.reserve(numCaptures);
   for (unsigned i = 0; i != numCaptures; ++i) {
-    VarDecl *decl = cast<VarDecl>(Reader.GetDecl(Record[Idx++]));
+    VarDecl *decl = ReadDeclAs<VarDecl>(Record, Idx);
     unsigned flags = Record[Idx++];
     bool byRef = (flags & 1);
     bool nested = (flags & 2);
@@ -800,9 +806,10 @@ void ASTDeclReader::VisitNamespaceDecl(NamespaceDecl *D) {
   D->NextNamespace = Record[Idx++];
 
   bool IsOriginal = Record[Idx++];
+  // FIXME: Modules will likely have trouble with pointing directly at
+  // the original namespace.
   D->OrigOrAnonNamespace.setInt(IsOriginal);
-  D->OrigOrAnonNamespace.setPointer(
-                    cast_or_null<NamespaceDecl>(Reader.GetDecl(Record[Idx++])));
+  D->OrigOrAnonNamespace.setPointer(ReadDeclAs<NamespaceDecl>(Record, Idx));
 }
 
 void ASTDeclReader::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
@@ -810,7 +817,7 @@ void ASTDeclReader::VisitNamespaceAliasDecl(NamespaceAliasDecl *D) {
   D->NamespaceLoc = ReadSourceLocation(Record, Idx);
   D->IdentLoc = ReadSourceLocation(Record, Idx);
   D->QualifierLoc = Reader.ReadNestedNameSpecifierLoc(F, Record, Idx);
-  D->Namespace = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+  D->Namespace = ReadDeclAs<NamedDecl>(Record, Idx);
 }
 
 void ASTDeclReader::VisitUsingDecl(UsingDecl *D) {
@@ -818,19 +825,17 @@ void ASTDeclReader::VisitUsingDecl(UsingDecl *D) {
   D->setUsingLocation(ReadSourceLocation(Record, Idx));
   D->QualifierLoc = Reader.ReadNestedNameSpecifierLoc(F, Record, Idx);
   ReadDeclarationNameLoc(D->DNLoc, D->getDeclName(), Record, Idx);
-  D->FirstUsingShadow = cast_or_null<UsingShadowDecl>(Reader.GetDecl(Record[Idx++]));
+  D->FirstUsingShadow = ReadDeclAs<UsingShadowDecl>(Record, Idx);
   D->setTypeName(Record[Idx++]);
-  NamedDecl *Pattern = cast_or_null<NamedDecl>(Reader.GetDecl(Record[Idx++]));
-  if (Pattern)
+  if (NamedDecl *Pattern = ReadDeclAs<NamedDecl>(Record, Idx))
     Reader.getContext()->setInstantiatedFromUsingDecl(D, Pattern);
 }
 
 void ASTDeclReader::VisitUsingShadowDecl(UsingShadowDecl *D) {
   VisitNamedDecl(D);
-  D->setTargetDecl(cast<NamedDecl>(Reader.GetDecl(Record[Idx++])));
-  D->UsingOrNextShadow = cast_or_null<NamedDecl>(Reader.GetDecl(Record[Idx++]));
-  UsingShadowDecl *Pattern
-      = cast_or_null<UsingShadowDecl>(Reader.GetDecl(Record[Idx++]));
+  D->setTargetDecl(ReadDeclAs<NamedDecl>(Record, Idx));
+  D->UsingOrNextShadow = ReadDeclAs<NamedDecl>(Record, Idx);
+  UsingShadowDecl *Pattern = ReadDeclAs<UsingShadowDecl>(Record, Idx);
   if (Pattern)
     Reader.getContext()->setInstantiatedFromUsingShadowDecl(D, Pattern);
 }
@@ -840,8 +845,8 @@ void ASTDeclReader::VisitUsingDirectiveDecl(UsingDirectiveDecl *D) {
   D->UsingLoc = ReadSourceLocation(Record, Idx);
   D->NamespaceLoc = ReadSourceLocation(Record, Idx);
   D->QualifierLoc = Reader.ReadNestedNameSpecifierLoc(F, Record, Idx);
-  D->NominatedNamespace = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
-  D->CommonAncestor = cast_or_null<DeclContext>(Reader.GetDecl(Record[Idx++]));
+  D->NominatedNamespace = ReadDeclAs<NamedDecl>(Record, Idx);
+  D->CommonAncestor = ReadDeclAs<DeclContext>(Record, Idx);
 }
 
 void ASTDeclReader::VisitUnresolvedUsingValueDecl(UnresolvedUsingValueDecl *D) {
@@ -898,11 +903,10 @@ void ASTDeclReader::ReadCXXDefinitionData(
   if (Data.NumVBases)
     Data.VBases = Reader.GetCXXBaseSpecifiersOffset(Record[Idx++]);
   
-  Reader.ReadUnresolvedSet(Data.Conversions, Record, Idx);
-  Reader.ReadUnresolvedSet(Data.VisibleConversions, Record, Idx);
+  Reader.ReadUnresolvedSet(F, Data.Conversions, Record, Idx);
+  Reader.ReadUnresolvedSet(F, Data.VisibleConversions, Record, Idx);
   assert(Data.Definition && "Data.Definition should be already set!");
-  Data.FirstFriend
-      = cast_or_null<FriendDecl>(Reader.GetDecl(Record[Idx++]));
+  Data.FirstFriend = ReadDeclAs<FriendDecl>(Record, Idx);
 }
 
 void ASTDeclReader::InitializeCXXDefinitionData(CXXRecordDecl *D,
@@ -942,8 +946,7 @@ void ASTDeclReader::InitializeCXXDefinitionData(CXXRecordDecl *D,
 void ASTDeclReader::VisitCXXRecordDecl(CXXRecordDecl *D) {
   VisitRecordDecl(D);
 
-  CXXRecordDecl *DefinitionDecl
-      = cast_or_null<CXXRecordDecl>(Reader.GetDecl(Record[Idx++]));
+  CXXRecordDecl *DefinitionDecl = ReadDeclAs<CXXRecordDecl>(Record, Idx);
   InitializeCXXDefinitionData(D, DefinitionDecl, Record, Idx);
 
   ASTContext &C = *Reader.getContext();
@@ -957,11 +960,10 @@ void ASTDeclReader::VisitCXXRecordDecl(CXXRecordDecl *D) {
   case CXXRecNotTemplate:
     break;
   case CXXRecTemplate:
-    D->TemplateOrInstantiation
-        = cast<ClassTemplateDecl>(Reader.GetDecl(Record[Idx++]));
+    D->TemplateOrInstantiation = ReadDeclAs<ClassTemplateDecl>(Record, Idx);
     break;
   case CXXRecMemberSpecialization: {
-    CXXRecordDecl *RD = cast<CXXRecordDecl>(Reader.GetDecl(Record[Idx++]));
+    CXXRecordDecl *RD = ReadDeclAs<CXXRecordDecl>(Record, Idx);
     TemplateSpecializationKind TSK = (TemplateSpecializationKind)Record[Idx++];
     SourceLocation POI = ReadSourceLocation(Record, Idx);
     MemberSpecializationInfo *MSI = new (C) MemberSpecializationInfo(RD, TSK);
@@ -974,9 +976,7 @@ void ASTDeclReader::VisitCXXRecordDecl(CXXRecordDecl *D) {
   // Load the key function to avoid deserializing every method so we can
   // compute it.
   if (D->IsDefinition) {
-    CXXMethodDecl *Key
-        = cast_or_null<CXXMethodDecl>(Reader.GetDecl(Record[Idx++]));
-    if (Key)
+    if (CXXMethodDecl *Key = ReadDeclAs<CXXMethodDecl>(Record, Idx))
       C.KeyFunctions[D] = Key;
   }
 }
@@ -985,10 +985,10 @@ void ASTDeclReader::VisitCXXMethodDecl(CXXMethodDecl *D) {
   VisitFunctionDecl(D);
   unsigned NumOverridenMethods = Record[Idx++];
   while (NumOverridenMethods--) {
-    CXXMethodDecl *MD = cast<CXXMethodDecl>(Reader.GetDecl(Record[Idx++]));
     // Avoid invariant checking of CXXMethodDecl::addOverriddenMethod,
     // MD may be initializing.
-    Reader.getContext()->addOverriddenMethod(D, MD);
+    if (CXXMethodDecl *MD = ReadDeclAs<CXXMethodDecl>(Record, Idx))
+      Reader.getContext()->addOverriddenMethod(D, MD);
   }
 }
 
@@ -1005,7 +1005,7 @@ void ASTDeclReader::VisitCXXDestructorDecl(CXXDestructorDecl *D) {
   VisitCXXMethodDecl(D);
 
   D->ImplicitlyDefined = Record[Idx++];
-  D->OperatorDelete = cast_or_null<FunctionDecl>(Reader.GetDecl(Record[Idx++]));
+  D->OperatorDelete = ReadDeclAs<FunctionDecl>(Record, Idx);
 }
 
 void ASTDeclReader::VisitCXXConversionDecl(CXXConversionDecl *D) {
@@ -1023,7 +1023,7 @@ void ASTDeclReader::VisitFriendDecl(FriendDecl *D) {
   if (Record[Idx++])
     D->Friend = GetTypeSourceInfo(Record, Idx);
   else
-    D->Friend = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+    D->Friend = ReadDeclAs<NamedDecl>(Record, Idx);
   D->NextFriend = Record[Idx++];
   D->UnsupportedFriend = (Record[Idx++] != 0);
   D->FriendLoc = ReadSourceLocation(Record, Idx);
@@ -1037,7 +1037,7 @@ void ASTDeclReader::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
   for (unsigned i = 0; i != NumParams; ++i)
     D->Params[i] = Reader.ReadTemplateParameterList(F, Record, Idx);
   if (Record[Idx++]) // HasFriendDecl
-    D->Friend = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+    D->Friend = ReadDeclAs<NamedDecl>(Record, Idx);
   else
     D->Friend = GetTypeSourceInfo(Record, Idx);
   D->FriendLoc = ReadSourceLocation(Record, Idx);
@@ -1046,8 +1046,7 @@ void ASTDeclReader::VisitFriendTemplateDecl(FriendTemplateDecl *D) {
 void ASTDeclReader::VisitTemplateDecl(TemplateDecl *D) {
   VisitNamedDecl(D);
 
-  NamedDecl *TemplatedDecl
-    = cast_or_null<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+  NamedDecl *TemplatedDecl = ReadDeclAs<NamedDecl>(Record, Idx);
   TemplateParameterList* TemplateParams
       = Reader.ReadTemplateParameterList(F, Record, Idx); 
   D->init(TemplatedDecl, TemplateParams);
@@ -1058,8 +1057,8 @@ void ASTDeclReader::VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D) {
   // can be used while this is still initializing.
 
   assert(D->CommonOrPrev.isNull() && "getCommonPtr was called earlier on this");
-  DeclID PreviousDeclID = Record[Idx++];
-  DeclID FirstDeclID =  PreviousDeclID ? Record[Idx++] : 0;
+  DeclID PreviousDeclID = ReadDeclID(Record, Idx);
+  DeclID FirstDeclID =  PreviousDeclID ? ReadDeclID(Record, Idx) : 0;
   // We delay loading of the redeclaration chain to avoid deeply nested calls.
   // We temporarily set the first (canonical) declaration as the previous one
   // which is the one that matters and mark the real previous DeclID to be
@@ -1076,7 +1075,7 @@ void ASTDeclReader::VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D) {
   } else {
     D->CommonOrPrev = D->newCommon(*Reader.getContext());
     if (RedeclarableTemplateDecl *RTD
-          = cast_or_null<RedeclarableTemplateDecl>(Reader.GetDecl(Record[Idx++]))) {
+          = ReadDeclAs<RedeclarableTemplateDecl>(Record, Idx)) {
       assert(RTD->getKind() == D->getKind() &&
              "InstantiatedFromMemberTemplate kind mismatch");
       D->setInstantiatedFromMemberTemplateImpl(RTD);
@@ -1084,8 +1083,8 @@ void ASTDeclReader::VisitRedeclarableTemplateDecl(RedeclarableTemplateDecl *D) {
         D->setMemberSpecialization();
     }
 
-    RedeclarableTemplateDecl *LatestDecl = 
-        cast_or_null<RedeclarableTemplateDecl>(Reader.GetDecl(Record[Idx++]));
+    RedeclarableTemplateDecl *LatestDecl
+      = ReadDeclAs<RedeclarableTemplateDecl>(Record, Idx);
   
     // This decl is a first one and the latest declaration that it points to is
     // in the same AST file. However, if this actually needs to point to a
@@ -1125,14 +1124,14 @@ void ASTDeclReader::VisitClassTemplateDecl(ClassTemplateDecl *D) {
     // Specializations.
     unsigned Size = Record[Idx++];
     SpecIDs[0] += Size;
-    SpecIDs.append(Record.begin() + Idx, Record.begin() + Idx + Size);
-    Idx += Size;
+    for (unsigned I = 0; I != Size; ++I)
+      SpecIDs.push_back(ReadDeclID(Record, Idx));
 
     // Partial specializations.
     Size = Record[Idx++];
     SpecIDs[0] += Size;
-    SpecIDs.append(Record.begin() + Idx, Record.begin() + Idx + Size);
-    Idx += Size;
+    for (unsigned I = 0; I != Size; ++I)
+      SpecIDs.push_back(ReadDeclID(Record, Idx));
 
     if (SpecIDs[0]) {
       typedef serialization::DeclID DeclID;
@@ -1153,7 +1152,7 @@ void ASTDeclReader::VisitClassTemplateSpecializationDecl(
   VisitCXXRecordDecl(D);
   
   ASTContext &C = *Reader.getContext();
-  if (Decl *InstD = Reader.GetDecl(Record[Idx++])) {
+  if (Decl *InstD = ReadDecl(Record, Idx)) {
     if (ClassTemplateDecl *CTD = dyn_cast<ClassTemplateDecl>(InstD)) {
       D->SpecializedTemplate = CTD;
     } else {
@@ -1190,8 +1189,7 @@ void ASTDeclReader::VisitClassTemplateSpecializationDecl(
   D->SpecializationKind = (TemplateSpecializationKind)Record[Idx++];
   
   if (D->isCanonicalDecl()) { // It's kept in the folding set.
-    ClassTemplateDecl *CanonPattern
-                       = cast<ClassTemplateDecl>(Reader.GetDecl(Record[Idx++]));
+    ClassTemplateDecl *CanonPattern = ReadDeclAs<ClassTemplateDecl>(Record,Idx);
     if (ClassTemplatePartialSpecializationDecl *Partial
                        = dyn_cast<ClassTemplatePartialSpecializationDecl>(D)) {
       CanonPattern->getCommonPtr()->PartialSpecializations.InsertNode(Partial);
@@ -1221,8 +1219,7 @@ void ASTDeclReader::VisitClassTemplatePartialSpecializationDecl(
   // These are read/set from/to the first declaration.
   if (D->getPreviousDeclaration() == 0) {
     D->InstantiatedFromMember.setPointer(
-        cast_or_null<ClassTemplatePartialSpecializationDecl>(
-                                                Reader.GetDecl(Record[Idx++])));
+      ReadDeclAs<ClassTemplatePartialSpecializationDecl>(Record, Idx));
     D->InstantiatedFromMember.setInt(Record[Idx++]);
   }
 }
@@ -1238,7 +1235,7 @@ void ASTDeclReader::VisitFunctionTemplateDecl(FunctionTemplateDecl *D) {
     // when reading the specialized FunctionDecl.
     unsigned NumSpecs = Record[Idx++];
     while (NumSpecs--)
-      Reader.GetDecl(Record[Idx++]);
+      (void)ReadDecl(Record, Idx);
   }
 }
 
@@ -1315,8 +1312,8 @@ void ASTDeclReader::VisitRedeclarable(Redeclarable<T> *D) {
   case NoRedeclaration:
     break;
   case PointsToPrevious: {
-    DeclID PreviousDeclID = Record[Idx++];
-    DeclID FirstDeclID = Record[Idx++];
+    DeclID PreviousDeclID = ReadDeclID(Record, Idx);
+    DeclID FirstDeclID = ReadDeclID(Record, Idx);
     // We delay loading of the redeclaration chain to avoid deeply nested calls.
     // We temporarily set the first (canonical) declaration as the previous one
     // which is the one that matters and mark the real previous DeclID to be
@@ -1330,7 +1327,7 @@ void ASTDeclReader::VisitRedeclarable(Redeclarable<T> *D) {
   }
   case PointsToLatest:
     D->RedeclLink = typename Redeclarable<T>::LatestDeclLink(
-                                cast_or_null<T>(Reader.GetDecl(Record[Idx++])));
+                                                   ReadDeclAs<T>(Record, Idx));
     break;
   }
 
@@ -1761,24 +1758,23 @@ void ASTDeclReader::UpdateDecl(Decl *D, ASTReader::PerFileData &Module,
     switch ((DeclUpdateKind)Record[Idx++]) {
     case UPD_CXX_SET_DEFINITIONDATA: {
       CXXRecordDecl *RD = cast<CXXRecordDecl>(D);
-      CXXRecordDecl *
-          DefinitionDecl = cast<CXXRecordDecl>(Reader.GetDecl(Record[Idx++]));
+      CXXRecordDecl *DefinitionDecl = ReadDeclAs<CXXRecordDecl>(Record, Idx);
       assert(!RD->DefinitionData && "DefinitionData is already set!");
       InitializeCXXDefinitionData(RD, DefinitionDecl, Record, Idx);
       break;
     }
 
     case UPD_CXX_ADDED_IMPLICIT_MEMBER:
-      cast<CXXRecordDecl>(D)->addedMember(Reader.GetDecl(Record[Idx++]));
+        cast<CXXRecordDecl>(D)->addedMember(ReadDecl(Record, Idx));
       break;
 
     case UPD_CXX_ADDED_TEMPLATE_SPECIALIZATION:
       // It will be added to the template's specializations set when loaded.
-      Reader.GetDecl(Record[Idx++]);
+      (void)ReadDecl(Record, Idx);
       break;
 
     case UPD_CXX_ADDED_ANONYMOUS_NAMESPACE: {
-      NamespaceDecl *Anon = cast<NamespaceDecl>(Reader.GetDecl(Record[Idx++]));
+      NamespaceDecl *Anon = ReadDeclAs<NamespaceDecl>(Record, Idx);
       // Guard against these being loaded out of original order. Don't use
       // getNextNamespace(), since it tries to access the context and can't in
       // the middle of deserialization.
diff --git a/clang/lib/Serialization/ASTReaderStmt.cpp b/clang/lib/Serialization/ASTReaderStmt.cpp
index 14927b9e3bc8..962fd2381187 100644
--- a/clang/lib/Serialization/ASTReaderStmt.cpp
+++ b/clang/lib/Serialization/ASTReaderStmt.cpp
@@ -22,27 +22,44 @@ using namespace clang::serialization;
 namespace clang {
 
   class ASTStmtReader : public StmtVisitor<ASTStmtReader> {
+    typedef ASTReader::RecordData RecordData;
+    
     ASTReader &Reader;
     ASTReader::PerFileData &F;
     llvm::BitstreamCursor &DeclsCursor;
     const ASTReader::RecordData &Record;
     unsigned &Idx;
 
-    SourceLocation ReadSourceLocation(const ASTReader::RecordData &R,
-                                      unsigned &I) {
+    SourceLocation ReadSourceLocation(const RecordData &R, unsigned &I) {
       return Reader.ReadSourceLocation(F, R, I);
     }
-    SourceRange ReadSourceRange(const ASTReader::RecordData &R, unsigned &I) {
+    
+    SourceRange ReadSourceRange(const RecordData &R, unsigned &I) {
       return Reader.ReadSourceRange(F, R, I);
     }
-    TypeSourceInfo *GetTypeSourceInfo(const ASTReader::RecordData &R,
-                                      unsigned &I) {
+    
+    TypeSourceInfo *GetTypeSourceInfo(const RecordData &R, unsigned &I) {
       return Reader.GetTypeSourceInfo(F, R, I);
     }
+    
+    serialization::DeclID ReadDeclID(const RecordData &R, unsigned &I) {
+      return Reader.ReadDeclID(F, R, I);
+    }
+    
+    Decl *ReadDecl(const RecordData &R, unsigned &I) {
+      return Reader.ReadDecl(F, R, I);
+    }
+    
+    template<typename T>
+    T *ReadDeclAs(const RecordData &R, unsigned &I) {
+      return Reader.ReadDeclAs<T>(F, R, I);
+    }
+
     void ReadDeclarationNameLoc(DeclarationNameLoc &DNLoc, DeclarationName Name,
                                 const ASTReader::RecordData &R, unsigned &I) {
       Reader.ReadDeclarationNameLoc(F, DNLoc, Name, R, I);
     }
+    
     void ReadDeclarationNameInfo(DeclarationNameInfo &NameInfo,
                                 const ASTReader::RecordData &R, unsigned &I) {
       Reader.ReadDeclarationNameInfo(F, NameInfo, R, I);
@@ -130,7 +147,7 @@ void ASTStmtReader::VisitDefaultStmt(DefaultStmt *S) {
 
 void ASTStmtReader::VisitLabelStmt(LabelStmt *S) {
   VisitStmt(S);
-  LabelDecl *LD = cast<LabelDecl>(Reader.GetDecl(Record[Idx++]));
+  LabelDecl *LD = ReadDeclAs<LabelDecl>(Record, Idx);
   LD->setStmt(S);
   S->setDecl(LD);
   S->setSubStmt(Reader.ReadSubStmt());
@@ -139,8 +156,8 @@ void ASTStmtReader::VisitLabelStmt(LabelStmt *S) {
 
 void ASTStmtReader::VisitIfStmt(IfStmt *S) {
   VisitStmt(S);
-  S->setConditionVariable(*Reader.getContext(),
-                          cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
+  S->setConditionVariable(*Reader.getContext(), 
+                          ReadDeclAs<VarDecl>(Record, Idx));
   S->setCond(Reader.ReadSubExpr());
   S->setThen(Reader.ReadSubStmt());
   S->setElse(Reader.ReadSubStmt());
@@ -151,7 +168,7 @@ void ASTStmtReader::VisitIfStmt(IfStmt *S) {
 void ASTStmtReader::VisitSwitchStmt(SwitchStmt *S) {
   VisitStmt(S);
   S->setConditionVariable(*Reader.getContext(),
-                          cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
+                          ReadDeclAs<VarDecl>(Record, Idx));
   S->setCond(Reader.ReadSubExpr());
   S->setBody(Reader.ReadSubStmt());
   S->setSwitchLoc(ReadSourceLocation(Record, Idx));
@@ -173,7 +190,8 @@ void ASTStmtReader::VisitSwitchStmt(SwitchStmt *S) {
 void ASTStmtReader::VisitWhileStmt(WhileStmt *S) {
   VisitStmt(S);
   S->setConditionVariable(*Reader.getContext(),
-                          cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
+                          ReadDeclAs<VarDecl>(Record, Idx));
+
   S->setCond(Reader.ReadSubExpr());
   S->setBody(Reader.ReadSubStmt());
   S->setWhileLoc(ReadSourceLocation(Record, Idx));
@@ -193,7 +211,7 @@ void ASTStmtReader::VisitForStmt(ForStmt *S) {
   S->setInit(Reader.ReadSubStmt());
   S->setCond(Reader.ReadSubExpr());
   S->setConditionVariable(*Reader.getContext(),
-                          cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
+                          ReadDeclAs<VarDecl>(Record, Idx));
   S->setInc(Reader.ReadSubExpr());
   S->setBody(Reader.ReadSubStmt());
   S->setForLoc(ReadSourceLocation(Record, Idx));
@@ -203,7 +221,7 @@ void ASTStmtReader::VisitForStmt(ForStmt *S) {
 
 void ASTStmtReader::VisitGotoStmt(GotoStmt *S) {
   VisitStmt(S);
-  S->setLabel(cast<LabelDecl>(Reader.GetDecl(Record[Idx++])));
+  S->setLabel(ReadDeclAs<LabelDecl>(Record, Idx));
   S->setGotoLoc(ReadSourceLocation(Record, Idx));
   S->setLabelLoc(ReadSourceLocation(Record, Idx));
 }
@@ -229,7 +247,7 @@ void ASTStmtReader::VisitReturnStmt(ReturnStmt *S) {
   VisitStmt(S);
   S->setRetValue(Reader.ReadSubExpr());
   S->setReturnLoc(ReadSourceLocation(Record, Idx));
-  S->setNRVOCandidate(cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
+  S->setNRVOCandidate(ReadDeclAs<VarDecl>(Record, Idx));
 }
 
 void ASTStmtReader::VisitDeclStmt(DeclStmt *S) {
@@ -239,12 +257,12 @@ void ASTStmtReader::VisitDeclStmt(DeclStmt *S) {
 
   if (Idx + 1 == Record.size()) {
     // Single declaration
-    S->setDeclGroup(DeclGroupRef(Reader.GetDecl(Record[Idx++])));
+    S->setDeclGroup(DeclGroupRef(ReadDecl(Record, Idx)));
   } else {
     llvm::SmallVector<Decl *, 16> Decls;
-    Decls.reserve(Record.size() - Idx);
-    for (unsigned N = Record.size(); Idx != N; ++Idx)
-      Decls.push_back(Reader.GetDecl(Record[Idx]));
+    Decls.reserve(Record.size() - Idx);    
+    for (unsigned N = Record.size(); Idx != N; )
+      Decls.push_back(ReadDecl(Record, Idx));
     S->setDeclGroup(DeclGroupRef(DeclGroup::Create(*Reader.getContext(),
                                                    Decls.data(),
                                                    Decls.size())));
@@ -318,13 +336,13 @@ void ASTStmtReader::VisitDeclRefExpr(DeclRefExpr *E) {
       = Reader.ReadNestedNameSpecifierLoc(F, Record, Idx);
 
   if (E->hasFoundDecl())
-    E->getInternalFoundDecl() = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+    E->getInternalFoundDecl() = ReadDeclAs<NamedDecl>(Record, Idx);
 
   if (E->hasExplicitTemplateArgs())
     ReadExplicitTemplateArgumentList(E->getExplicitTemplateArgs(),
                                      NumTemplateArgs);
 
-  E->setDecl(cast<ValueDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setDecl(ReadDeclAs<ValueDecl>(Record, Idx));
   E->setLocation(ReadSourceLocation(Record, Idx));
   ReadDeclarationNameLoc(E->DNLoc, E->getDecl()->getDeclName(), Record, Idx);
 }
@@ -418,10 +436,7 @@ void ASTStmtReader::VisitOffsetOfExpr(OffsetOfExpr *E) {
       break;
         
     case Node::Field:
-      E->setComponent(I, 
-             Node(Start,  
-                  dyn_cast_or_null<FieldDecl>(Reader.GetDecl(Record[Idx++])),
-                  End));
+      E->setComponent(I, Node(Start, ReadDeclAs<FieldDecl>(Record, Idx), End));
       break;
 
     case Node::Identifier:
@@ -593,8 +608,7 @@ void ASTStmtReader::VisitInitListExpr(InitListExpr *E) {
     filler = Reader.ReadSubExpr();
     E->ArrayFillerOrUnionFieldInit = filler;
   } else
-    E->ArrayFillerOrUnionFieldInit
-        = cast_or_null<FieldDecl>(Reader.GetDecl(Record[Idx++]));
+    E->ArrayFillerOrUnionFieldInit = ReadDeclAs<FieldDecl>(Record, Idx);
   E->sawArrayRangeDesignator(Record[Idx++]);
   unsigned NumInits = Record[Idx++];
   E->reserveInits(*Reader.getContext(), NumInits);
@@ -624,7 +638,7 @@ void ASTStmtReader::VisitDesignatedInitExpr(DesignatedInitExpr *E) {
   while (Idx < Record.size()) {
     switch ((DesignatorTypes)Record[Idx++]) {
     case DESIG_FIELD_DECL: {
-      FieldDecl *Field = cast<FieldDecl>(Reader.GetDecl(Record[Idx++]));
+      FieldDecl *Field = ReadDeclAs<FieldDecl>(Record, Idx);
       SourceLocation DotLoc
         = ReadSourceLocation(Record, Idx);
       SourceLocation FieldLoc
@@ -689,7 +703,7 @@ void ASTStmtReader::VisitAddrLabelExpr(AddrLabelExpr *E) {
   VisitExpr(E);
   E->setAmpAmpLoc(ReadSourceLocation(Record, Idx));
   E->setLabelLoc(ReadSourceLocation(Record, Idx));
-  E->setLabel(cast<LabelDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setLabel(ReadDeclAs<LabelDecl>(Record, Idx));
 }
 
 void ASTStmtReader::VisitStmtExpr(StmtExpr *E) {
@@ -726,12 +740,12 @@ void ASTStmtReader::VisitShuffleVectorExpr(ShuffleVectorExpr *E) {
 
 void ASTStmtReader::VisitBlockExpr(BlockExpr *E) {
   VisitExpr(E);
-  E->setBlockDecl(cast_or_null<BlockDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setBlockDecl(ReadDeclAs<BlockDecl>(Record, Idx));
 }
 
 void ASTStmtReader::VisitBlockDeclRefExpr(BlockDeclRefExpr *E) {
   VisitExpr(E);
-  E->setDecl(cast<VarDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setDecl(ReadDeclAs<VarDecl>(Record, Idx));
   E->setLocation(ReadSourceLocation(Record, Idx));
   E->setByRef(Record[Idx++]);
   E->setConstQualAdded(Record[Idx++]);
@@ -781,14 +795,14 @@ void ASTStmtReader::VisitObjCSelectorExpr(ObjCSelectorExpr *E) {
 
 void ASTStmtReader::VisitObjCProtocolExpr(ObjCProtocolExpr *E) {
   VisitExpr(E);
-  E->setProtocol(cast<ObjCProtocolDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setProtocol(ReadDeclAs<ObjCProtocolDecl>(Record, Idx));
   E->setAtLoc(ReadSourceLocation(Record, Idx));
   E->setRParenLoc(ReadSourceLocation(Record, Idx));
 }
 
 void ASTStmtReader::VisitObjCIvarRefExpr(ObjCIvarRefExpr *E) {
   VisitExpr(E);
-  E->setDecl(cast<ObjCIvarDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setDecl(ReadDeclAs<ObjCIvarDecl>(Record, Idx));
   E->setLocation(ReadSourceLocation(Record, Idx));
   E->setBase(Reader.ReadSubExpr());
   E->setIsArrow(Record[Idx++]);
@@ -799,14 +813,11 @@ void ASTStmtReader::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
   VisitExpr(E);
   bool Implicit = Record[Idx++] != 0;
   if (Implicit) {
-    ObjCMethodDecl *Getter =
-      cast<ObjCMethodDecl>(Reader.GetDecl(Record[Idx++]));
-    ObjCMethodDecl *Setter =
-      cast<ObjCMethodDecl>(Reader.GetDecl(Record[Idx++]));
+    ObjCMethodDecl *Getter = ReadDeclAs<ObjCMethodDecl>(Record, Idx);
+    ObjCMethodDecl *Setter = ReadDeclAs<ObjCMethodDecl>(Record, Idx);
     E->setImplicitProperty(Getter, Setter);
   } else {
-    E->setExplicitProperty(
-                      cast<ObjCPropertyDecl>(Reader.GetDecl(Record[Idx++])));
+    E->setExplicitProperty(ReadDeclAs<ObjCPropertyDecl>(Record, Idx));
   }
   E->setLocation(ReadSourceLocation(Record, Idx));
   E->setReceiverLocation(ReadSourceLocation(Record, Idx));
@@ -818,8 +829,7 @@ void ASTStmtReader::VisitObjCPropertyRefExpr(ObjCPropertyRefExpr *E) {
     E->setSuperReceiver(Reader.GetType(Record[Idx++]));
     break;
   case 2:
-    E->setClassReceiver(
-                     cast<ObjCInterfaceDecl>(Reader.GetDecl(Record[Idx++])));
+    E->setClassReceiver(ReadDeclAs<ObjCInterfaceDecl>(Record, Idx));
     break;
   }
 }
@@ -852,7 +862,7 @@ void ASTStmtReader::VisitObjCMessageExpr(ObjCMessageExpr *E) {
   assert(Kind == E->getReceiverKind());
 
   if (Record[Idx++])
-    E->setMethodDecl(cast_or_null<ObjCMethodDecl>(Reader.GetDecl(Record[Idx++])));
+    E->setMethodDecl(ReadDeclAs<ObjCMethodDecl>(Record, Idx));
   else
     E->setSelector(Reader.GetSelector(Record, Idx));
 
@@ -876,7 +886,7 @@ void ASTStmtReader::VisitObjCForCollectionStmt(ObjCForCollectionStmt *S) {
 void ASTStmtReader::VisitObjCAtCatchStmt(ObjCAtCatchStmt *S) {
   VisitStmt(S);
   S->setCatchBody(Reader.ReadSubStmt());
-  S->setCatchParamDecl(cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++])));
+  S->setCatchParamDecl(ReadDeclAs<VarDecl>(Record, Idx));
   S->setAtCatchLoc(ReadSourceLocation(Record, Idx));
   S->setRParenLoc(ReadSourceLocation(Record, Idx));
 }
@@ -927,7 +937,7 @@ void ASTStmtReader::VisitObjCAtThrowStmt(ObjCAtThrowStmt *S) {
 void ASTStmtReader::VisitCXXCatchStmt(CXXCatchStmt *S) {
   VisitStmt(S);
   S->CatchLoc = ReadSourceLocation(Record, Idx);
-  S->ExceptionDecl = cast_or_null<VarDecl>(Reader.GetDecl(Record[Idx++]));
+  S->ExceptionDecl = ReadDeclAs<VarDecl>(Record, Idx);
   S->HandlerBlock = Reader.ReadSubStmt();
 }
 
@@ -966,7 +976,7 @@ void ASTStmtReader::VisitCXXConstructExpr(CXXConstructExpr *E) {
     E->Args = new (*Reader.getContext()) Stmt*[E->NumArgs];
   for (unsigned I = 0, N = E->getNumArgs(); I != N; ++I)
     E->setArg(I, Reader.ReadSubExpr());
-  E->setConstructor(cast<CXXConstructorDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setConstructor(ReadDeclAs<CXXConstructorDecl>(Record, Idx));
   E->setLocation(ReadSourceLocation(Record, Idx));
   E->setElidable(Record[Idx++]);  
   E->setRequiresZeroInitialization(Record[Idx++]);
@@ -1050,13 +1060,13 @@ void ASTStmtReader::VisitCXXDefaultArgExpr(CXXDefaultArgExpr *E) {
 
   assert(Record[Idx] == E->Param.getInt() && "We messed up at creation ?");
   ++Idx; // HasOtherExprStored and SubExpr was handled during creation.
-  E->Param.setPointer(cast<ParmVarDecl>(Reader.GetDecl(Record[Idx++])));
+  E->Param.setPointer(ReadDeclAs<ParmVarDecl>(Record, Idx));
   E->Loc = ReadSourceLocation(Record, Idx);
 }
 
 void ASTStmtReader::VisitCXXBindTemporaryExpr(CXXBindTemporaryExpr *E) {
   VisitExpr(E);
-  E->setTemporary(Reader.ReadCXXTemporary(Record, Idx));
+  E->setTemporary(Reader.ReadCXXTemporary(F, Record, Idx));
   E->setSubExpr(Reader.ReadSubExpr());
 }
 
@@ -1074,11 +1084,9 @@ void ASTStmtReader::VisitCXXNewExpr(CXXNewExpr *E) {
   bool isArray = Record[Idx++];
   unsigned NumPlacementArgs = Record[Idx++];
   unsigned NumCtorArgs = Record[Idx++];
-  E->setOperatorNew(cast_or_null<FunctionDecl>(Reader.GetDecl(Record[Idx++])));
-  E->setOperatorDelete(
-                    cast_or_null<FunctionDecl>(Reader.GetDecl(Record[Idx++])));
-  E->setConstructor(
-               cast_or_null<CXXConstructorDecl>(Reader.GetDecl(Record[Idx++])));
+  E->setOperatorNew(ReadDeclAs<FunctionDecl>(Record, Idx));
+  E->setOperatorDelete(ReadDeclAs<FunctionDecl>(Record, Idx));
+  E->setConstructor(ReadDeclAs<CXXConstructorDecl>(Record, Idx));
   E->AllocatedTypeInfo = GetTypeSourceInfo(Record, Idx);
   SourceRange TypeIdParens;
   TypeIdParens.setBegin(ReadSourceLocation(Record, Idx));
@@ -1104,7 +1112,7 @@ void ASTStmtReader::VisitCXXDeleteExpr(CXXDeleteExpr *E) {
   E->ArrayForm = Record[Idx++];
   E->ArrayFormAsWritten = Record[Idx++];
   E->UsualArrayDeleteWantsSize = Record[Idx++];
-  E->OperatorDelete = cast_or_null<FunctionDecl>(Reader.GetDecl(Record[Idx++]));
+  E->OperatorDelete = ReadDeclAs<FunctionDecl>(Record, Idx);
   E->Argument = Reader.ReadSubExpr();
   E->Loc = ReadSourceLocation(Record, Idx);
 }
@@ -1133,7 +1141,7 @@ void ASTStmtReader::VisitExprWithCleanups(ExprWithCleanups *E) {
   if (NumTemps) {
     E->setNumTemporaries(*Reader.getContext(), NumTemps);
     for (unsigned i = 0; i != NumTemps; ++i)
-      E->setTemporary(i, Reader.ReadCXXTemporary(Record, Idx));
+      E->setTemporary(i, Reader.ReadCXXTemporary(F, Record, Idx));
   }
   E->setSubExpr(Reader.ReadSubExpr());
 }
@@ -1151,8 +1159,7 @@ ASTStmtReader::VisitCXXDependentScopeMemberExpr(CXXDependentScopeMemberExpr *E){
   E->IsArrow = Record[Idx++];
   E->OperatorLoc = ReadSourceLocation(Record, Idx);
   E->QualifierLoc = Reader.ReadNestedNameSpecifierLoc(F, Record, Idx);
-  E->FirstQualifierFoundInScope
-                      = cast_or_null<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+  E->FirstQualifierFoundInScope = ReadDeclAs<NamedDecl>(Record, Idx);
   ReadDeclarationNameInfo(E->MemberNameInfo, Record, Idx);
 }
 
@@ -1191,7 +1198,7 @@ void ASTStmtReader::VisitOverloadExpr(OverloadExpr *E) {
   unsigned NumDecls = Record[Idx++];
   UnresolvedSet<8> Decls;
   for (unsigned i = 0; i != NumDecls; ++i) {
-    NamedDecl *D = cast<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+    NamedDecl *D = ReadDeclAs<NamedDecl>(Record, Idx);
     AccessSpecifier AS = (AccessSpecifier)Record[Idx++];
     Decls.addDecl(D, AS);
   }
@@ -1216,7 +1223,7 @@ void ASTStmtReader::VisitUnresolvedLookupExpr(UnresolvedLookupExpr *E) {
   if (E->RequiresADL)
     E->StdIsAssociatedNamespace = Record[Idx++];
   E->Overloaded = Record[Idx++];
-  E->NamingClass = cast_or_null<CXXRecordDecl>(Reader.GetDecl(Record[Idx++]));
+  E->NamingClass = ReadDeclAs<CXXRecordDecl>(Record, Idx);
 }
 
 void ASTStmtReader::VisitUnaryTypeTraitExpr(UnaryTypeTraitExpr *E) {
@@ -1280,14 +1287,13 @@ void ASTStmtReader::VisitSizeOfPackExpr(SizeOfPackExpr *E) {
   E->PackLoc = ReadSourceLocation(Record, Idx);
   E->RParenLoc = ReadSourceLocation(Record, Idx);
   E->Length = Record[Idx++];
-  E->Pack = cast_or_null<NamedDecl>(Reader.GetDecl(Record[Idx++]));
+  E->Pack = ReadDeclAs<NamedDecl>(Record, Idx);
 }
 
 void ASTStmtReader::VisitSubstNonTypeTemplateParmExpr(
                                               SubstNonTypeTemplateParmExpr *E) {
   VisitExpr(E);
-  E->Param
-    = cast_or_null<NonTypeTemplateParmDecl>(Reader.GetDecl(Record[Idx++]));
+  E->Param = ReadDeclAs<NonTypeTemplateParmDecl>(Record, Idx);
   E->NameLoc = ReadSourceLocation(Record, Idx);
   E->Replacement = Reader.ReadSubExpr();
 }
@@ -1295,8 +1301,7 @@ void ASTStmtReader::VisitSubstNonTypeTemplateParmExpr(
 void ASTStmtReader::VisitSubstNonTypeTemplateParmPackExpr(
                                           SubstNonTypeTemplateParmPackExpr *E) {
   VisitExpr(E);
-  E->Param
-    = cast_or_null<NonTypeTemplateParmDecl>(Reader.GetDecl(Record[Idx++]));
+  E->Param = ReadDeclAs<NonTypeTemplateParmDecl>(Record, Idx);
   TemplateArgument ArgPack = Reader.ReadTemplateArgument(F, Record, Idx);
   if (ArgPack.getKind() != TemplateArgument::Pack)
     return;
@@ -1611,7 +1616,7 @@ Stmt *ASTReader::ReadStmtFromStream(PerFileData &F) {
           ArgInfo.addArgument(ReadTemplateArgumentLoc(F, Record, Idx));
       }
       
-      NamedDecl *FoundD = cast_or_null<NamedDecl>(GetDecl(Record[Idx++]));
+      NamedDecl *FoundD = ReadDeclAs<NamedDecl>(F, Record, Idx);
       AccessSpecifier AS = (AccessSpecifier)Record[Idx++];
       DeclAccessPair FoundDecl = DeclAccessPair::make(FoundD, AS);
 
@@ -1619,7 +1624,7 @@ Stmt *ASTReader::ReadStmtFromStream(PerFileData &F) {
       ExprValueKind VK = static_cast<ExprValueKind>(Record[Idx++]);
       ExprObjectKind OK = static_cast<ExprObjectKind>(Record[Idx++]);
       Expr *Base = ReadSubExpr();
-      ValueDecl *MemberD = cast<ValueDecl>(GetDecl(Record[Idx++]));
+      ValueDecl *MemberD = ReadDeclAs<ValueDecl>(F, Record, Idx);
       SourceLocation MemberLoc = ReadSourceLocation(F, Record, Idx);
       DeclarationNameInfo MemberNameInfo(MemberD->getDeclName(), MemberLoc);
       bool IsArrow = Record[Idx++];