Index: include/clang/AST/ExternalASTMerger.h
===================================================================
--- include/clang/AST/ExternalASTMerger.h
+++ include/clang/AST/ExternalASTMerger.h
@@ -21,21 +21,29 @@
 
 class ExternalASTMerger : public ExternalASTSource {
 public:
-  struct ImporterPair {
-    std::unique_ptr<ASTImporter> Forward;
-    std::unique_ptr<ASTImporter> Reverse;
+  struct DCOrigin {
+    DeclContext *DC;
+    ASTContext *AST;
   };
 
+  typedef llvm::DenseMap<const DeclContext *, DCOrigin> OriginMap;
+  typedef std::vector<std::unique_ptr<ASTImporter>> ImporterVector;
 private:
-  std::vector<ImporterPair> Importers;
+  ImporterVector Importers;
+  OriginMap Origins;
 
 public:
-  struct ImporterEndpoint {
+  struct ImporterTarget {
     ASTContext &AST;
     FileManager &FM;
   };
-  ExternalASTMerger(const ImporterEndpoint &Target,
-                    llvm::ArrayRef<ImporterEndpoint> Sources);
+  struct ImporterSource {
+    ASTContext &AST;
+    FileManager &FM;
+    const OriginMap &OM;
+  };
+  ExternalASTMerger(const ImporterTarget &Target,
+                    llvm::ArrayRef<ImporterSource> Sources);
 
   bool FindExternalVisibleDeclsByName(const DeclContext *DC,
                                       DeclarationName Name) override;
@@ -44,6 +52,21 @@
   FindExternalLexicalDecls(const DeclContext *DC,
                            llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
                            SmallVectorImpl<Decl *> &Result) override;
+
+  void CompleteType(clang::TagDecl *Tag) override;
+  void CompleteType(clang::ObjCInterfaceDecl *Interface) override;
+
+  void MaybeRecordOrigin(DeclContext *ToDC, DCOrigin Origin);
+  void ForceRecordOrigin(DeclContext *ToDC, DCOrigin Origin);
+  const OriginMap &GetOrigins() { return Origins; }
+
+  bool HasImporterForOrigin(ASTContext &OriginContext);
+  ASTImporter &ImporterForOrigin(ASTContext &OriginContext);
+private:
+  void RecordOriginImpl(DeclContext *ToDC, DCOrigin Origin,
+                                  ASTImporter &importer);
+  template <typename CallbackType>
+  void ForEachMatchingDC(const DeclContext *DC, CallbackType Callback);
 };
 
 } // end namespace clang
Index: lib/AST/ExternalASTMerger.cpp
===================================================================
--- lib/AST/ExternalASTMerger.cpp
+++ lib/AST/ExternalASTMerger.cpp
@@ -14,6 +14,7 @@
 
 #include "clang/AST/ASTContext.h"
 #include "clang/AST/Decl.h"
+#include "clang/AST/DeclCXX.h"
 #include "clang/AST/DeclObjC.h"
 #include "clang/AST/ExternalASTMerger.h"
 
@@ -32,29 +33,16 @@
 
 typedef std::pair<Source<NamedDecl *>, ASTImporter *> Candidate;
 
-class LazyASTImporter : public ASTImporter {
-public:
-  LazyASTImporter(ASTContext &ToContext, FileManager &ToFileManager,
-                  ASTContext &FromContext, FileManager &FromFileManager)
-      : ASTImporter(ToContext, ToFileManager, FromContext, FromFileManager,
-                    /*MinimalImport=*/true) {}
-  Decl *Imported(Decl *From, Decl *To) override {
-    if (auto ToTag = dyn_cast<TagDecl>(To)) {
-      ToTag->setHasExternalLexicalStorage();
-      ToTag->setMustBuildLookupTable();
-    } else if (auto ToNamespace = dyn_cast<NamespaceDecl>(To)) {
-      ToNamespace->setHasExternalVisibleStorage();
-    } else if (auto ToContainer = dyn_cast<ObjCContainerDecl>(To)) {
-      ToContainer->setHasExternalLexicalStorage();
-      ToContainer->setMustBuildLookupTable();
-    }
-    return ASTImporter::Imported(From, To);
-  }
-};
+const DeclContext *CanonicalizeDC(const DeclContext *DC) {
+  if (isa<LinkageSpecDecl>(DC))
+    return DC->getRedeclContext();
+  return DC;
+}
 
 Source<const DeclContext *>
 LookupSameContext(Source<TranslationUnitDecl *> SourceTU, const DeclContext *DC,
                   ASTImporter &ReverseImporter) {
+  DC = CanonicalizeDC(DC);
   if (DC->isTranslationUnit()) {
     return SourceTU;
   }
@@ -70,95 +58,220 @@
   DeclContext::lookup_result SearchResult =
       SourceParentDC.get()->lookup(SourceName.get());
   size_t SearchResultSize = SearchResult.size();
-  // Handle multiple candidates once we have a test for it.
-  // This may turn up when we import template specializations correctly.
-  assert(SearchResultSize < 2);
-  if (SearchResultSize == 0) {
-    // couldn't find the name, so we have to give up
+  if (SearchResultSize == 0 || SearchResultSize > 1) {
+    // There are two cases here.  First, we might not find the name.
+    // We might also find multiple copies, in which case we have no
+    // guarantee that the one we wanted is the one we pick.  (E.g.,
+    // if we have two specializations of the same template it is
+    // very hard to determine which is the one you want.)
+    //
+    // Since we have the Origins map, the most reliable solution here
+    // is to rely on that and give up on being able to find better
+    // versions elsewhere.
     return nullptr;
   } else {
     NamedDecl *SearchResultDecl = SearchResult[0];
-    return dyn_cast<DeclContext>(SearchResultDecl);
+    if (isa<DeclContext>(SearchResultDecl) &&
+        SearchResultDecl->getKind() == DC->getDeclKind())
+      return cast<DeclContext>(SearchResultDecl)->getPrimaryContext();
+    else
+      return nullptr; // This type of lookup is unsupported
   }
 }
 
-bool IsForwardDeclaration(Decl *D) {
-  if (auto TD = dyn_cast<TagDecl>(D)) {
-    return !TD->isThisDeclarationADefinition();
-  } else if (auto FD = dyn_cast<FunctionDecl>(D)) {
-    return !FD->isThisDeclarationADefinition();
-  } else if (auto OID = dyn_cast<ObjCInterfaceDecl>(D)) {
-     return OID->isThisDeclarationADefinition();
-  } else {
+class LazyASTImporter : public ASTImporter {
+private:
+  ExternalASTMerger &Parent;
+  ASTImporter Reverse;
+  const ExternalASTMerger::OriginMap &FromOrigins;
+public:
+  LazyASTImporter(ExternalASTMerger &_Parent, ASTContext &ToContext,
+                  FileManager &ToFileManager, ASTContext &FromContext,
+                  FileManager &FromFileManager,
+                  const ExternalASTMerger::OriginMap &_FromOrigins)
+      : ASTImporter(ToContext, ToFileManager, FromContext, FromFileManager,
+                    /*MinimalImport=*/true),
+        Parent(_Parent), Reverse(FromContext, FromFileManager, ToContext,
+                                 ToFileManager, /*MinimalImport=*/true), FromOrigins(_FromOrigins) {}
+  Decl *Imported(Decl *From, Decl *To) override {
+    if (auto *ToDC = dyn_cast<DeclContext>(To)) {
+      Source<DeclContext *> FromDC(
+          cast<DeclContext>(From)->getPrimaryContext());
+      if (FromOrigins.count(FromDC) &&
+          Parent.HasImporterForOrigin(*FromOrigins.lookup(FromDC).AST))
+        Parent.ForceRecordOrigin(ToDC, FromOrigins.lookup(FromDC));
+      else
+        Parent.MaybeRecordOrigin(ToDC, {FromDC, &getFromContext()});
+    }
+    if (auto ToTag = dyn_cast<TagDecl>(To)) {
+      ToTag->setHasExternalLexicalStorage();
+      ToTag->setMustBuildLookupTable();
+    } else if (auto ToNamespace = dyn_cast<NamespaceDecl>(To)) {
+      ToNamespace->setHasExternalVisibleStorage();
+    } else if (auto ToContainer = dyn_cast<ObjCContainerDecl>(To)) {
+      ToContainer->setHasExternalLexicalStorage();
+      ToContainer->setMustBuildLookupTable();
+    }
+    return ASTImporter::Imported(From, To);
+  }
+  ASTImporter &GetReverse() { return Reverse; }
+};
+
+bool HasDeclOfSameType(llvm::ArrayRef<Candidate> Decls, const Candidate &C) {
+  if (isa<FunctionDecl>(C.first.get()))
     return false;
+  return llvm::any_of(Decls, [&](const Candidate &D) {    return C.first.get()->getKind() == D.first.get()->getKind();
+  });
+}
+
+} // end namespace
+
+ASTImporter &ExternalASTMerger::ImporterForOrigin(ASTContext &OriginContext) {
+  for (const std::unique_ptr<ASTImporter> &I : Importers) {
+    if (&I->getFromContext() == &OriginContext)
+      return *I;
   }
+  llvm_unreachable("We should have an importer for this origin!");
 }
 
+namespace {
+LazyASTImporter &LazyImporterForOrigin(ExternalASTMerger &merger,
+                                   ASTContext &OriginContext) {
+  return static_cast<LazyASTImporter &>(
+      merger.ImporterForOrigin(OriginContext));
+}
+}
+
+bool ExternalASTMerger::HasImporterForOrigin(ASTContext &OriginContext) {
+  for (const std::unique_ptr<ASTImporter> &I : Importers) {
+    if (&I->getFromContext() == &OriginContext)
+      return true;
+  }
+  return false;
+}
+
 template <typename CallbackType>
-void ForEachMatchingDC(
-    const DeclContext *DC,
-    llvm::ArrayRef<ExternalASTMerger::ImporterPair> Importers,
-    CallbackType Callback) {
-  for (const ExternalASTMerger::ImporterPair &IP : Importers) {
-    Source<TranslationUnitDecl *> SourceTU =
-        IP.Forward->getFromContext().getTranslationUnitDecl();
-    if (auto SourceDC = LookupSameContext(SourceTU, DC, *IP.Reverse))
-      Callback(IP, SourceDC);
+void ExternalASTMerger::ForEachMatchingDC(const DeclContext *DC,
+                                          CallbackType Callback) {
+  if (Origins.count(DC)) {
+    ExternalASTMerger::DCOrigin Origin = Origins[DC];
+    LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
+    Callback(Importer, Importer.GetReverse(), Origin.DC);
+  } else {
+    bool DidCallback = false;
+    for (const std::unique_ptr<ASTImporter> &Importer : Importers) {
+      Source<TranslationUnitDecl *> SourceTU =
+          Importer->getFromContext().getTranslationUnitDecl();
+      ASTImporter &Reverse =
+          static_cast<LazyASTImporter *>(Importer.get())->GetReverse();
+      if (auto SourceDC = LookupSameContext(SourceTU, DC, Reverse)) {
+        DidCallback = true;
+        if (Callback(*Importer, Reverse, SourceDC))
+          break;
+      }
+    }
+    assert(DidCallback && "Couldn't find a source context matching our DC");
   }
 }
 
-bool HasDeclOfSameType(llvm::ArrayRef<Candidate> Decls, const Candidate &C) {
-  return llvm::any_of(Decls, [&](const Candidate &D) {
-    return C.first.get()->getKind() == D.first.get()->getKind();
+void ExternalASTMerger::CompleteType(clang::TagDecl *Tag) {
+  assert(Tag->hasExternalLexicalStorage());
+  ForEachMatchingDC(Tag, [&](ASTImporter &Forward, ASTImporter &Reverse,
+                             Source<const DeclContext *> SourceDC) -> bool {
+    auto *SourceTag = const_cast<TagDecl *>(cast<TagDecl>(SourceDC.get()));
+    if (SourceTag->hasExternalLexicalStorage())
+      SourceTag->getASTContext().getExternalSource()->CompleteType(SourceTag);
+    if (!SourceTag->getDefinition())
+      return false;
+    Forward.Imported(SourceTag, Tag);
+    Forward.ImportDefinition(SourceTag);
+    Tag->setCompleteDefinition(SourceTag->isCompleteDefinition());
+    return true;
   });
 }
-} // end namespace
 
-ExternalASTMerger::ExternalASTMerger(const ImporterEndpoint &Target,
-                                     llvm::ArrayRef<ImporterEndpoint> Sources) {
-  for (const ImporterEndpoint &S : Sources) {
-    Importers.push_back(
-        {llvm::make_unique<LazyASTImporter>(Target.AST, Target.FM, S.AST, S.FM),
-         llvm::make_unique<ASTImporter>(S.AST, S.FM, Target.AST, Target.FM,
-                                        /*MinimalImport=*/true)});
+void ExternalASTMerger::CompleteType(clang::ObjCInterfaceDecl *Interface) {
+  assert(Interface->hasExternalLexicalStorage());
+  ForEachMatchingDC(Interface, [&](ASTImporter &Forward, ASTImporter &Reverse,
+                            Source<const DeclContext *> SourceDC) -> bool {
+    auto *SourceInterface = const_cast<ObjCInterfaceDecl *>(cast<ObjCInterfaceDecl>(SourceDC.get()));
+    if (SourceInterface->hasExternalLexicalStorage())
+      SourceInterface->getASTContext().getExternalSource()->CompleteType(SourceInterface);
+    if (!SourceInterface->getDefinition())
+      return false;
+    Forward.Imported(SourceInterface, Interface);
+    Forward.ImportDefinition(SourceInterface);
+    return true;
+  });
+}
+
+namespace {
+bool IsSameDC(const DeclContext *D1, const DeclContext *D2) {
+  if (isa<ObjCContainerDecl>(D1) && isa<ObjCContainerDecl>(D2))
+    return true; // There are many cases where Objective-C is ambiguous.
+  if (auto T1 = dyn_cast<TagDecl>(D1))
+    if (auto T2 = dyn_cast<TagDecl>(D2))
+      if (T1->getFirstDecl() == T2->getFirstDecl())
+        return true;
+  return D1 == D2 || D1 == CanonicalizeDC(D2);
+}
+}
+
+void ExternalASTMerger::MaybeRecordOrigin(DeclContext *ToDC, DCOrigin Origin) {
+  LazyASTImporter &Importer = LazyImporterForOrigin(*this, *Origin.AST);
+  ASTImporter &Reverse = Importer.GetReverse();
+  Source<const DeclContext *> FoundFromDC =
+      LookupSameContext(Origin.AST->getTranslationUnitDecl(), ToDC, Reverse);
+  if (!FoundFromDC || !IsSameDC(FoundFromDC.get(), Origin.DC)) {
+    RecordOriginImpl(ToDC, Origin, Importer);
   }
 }
 
+void ExternalASTMerger::ForceRecordOrigin(DeclContext *ToDC,
+                                          DCOrigin Origin) {
+  RecordOriginImpl(ToDC, Origin, ImporterForOrigin(*Origin.AST));
+}
+
+void ExternalASTMerger::RecordOriginImpl(DeclContext *ToDC, DCOrigin Origin,
+                                         ASTImporter &Importer) {
+  Origins[ToDC] = Origin;
+  Importer.ASTImporter::Imported(cast<Decl>(Origin.DC), cast<Decl>(ToDC));
+}
+
+ExternalASTMerger::ExternalASTMerger(const ImporterTarget &Target,
+                                     llvm::ArrayRef<ImporterSource> Sources) {
+  for (const ImporterSource &S : Sources) {
+    Importers.push_back(llvm::make_unique<LazyASTImporter>(
+        *this, Target.AST, Target.FM, S.AST, S.FM, S.OM));
+  }
+}
+
 bool ExternalASTMerger::FindExternalVisibleDeclsByName(const DeclContext *DC,
                                                        DeclarationName Name) {
   llvm::SmallVector<NamedDecl *, 1> Decls;
-  llvm::SmallVector<Candidate, 4> CompleteDecls;
-  llvm::SmallVector<Candidate, 4> ForwardDecls;
+  llvm::SmallVector<Candidate, 4> Candidates;
 
-  auto FilterFoundDecl = [&CompleteDecls, &ForwardDecls](const Candidate &C) {
-    if (IsForwardDeclaration(C.first.get())) {
-      if (!HasDeclOfSameType(ForwardDecls, C)) {
-        ForwardDecls.push_back(C);
-      }
-    } else {
-      CompleteDecls.push_back(C);
-    }
+  auto FilterFoundDecl = [&Candidates](const Candidate &C) {
+   if (!HasDeclOfSameType(Candidates, C))
+     Candidates.push_back(C);
   };
 
-  ForEachMatchingDC(
-      DC, Importers,
-      [&](const ImporterPair &IP, Source<const DeclContext *> SourceDC) {
-        DeclarationName FromName = IP.Reverse->Import(Name);
-        DeclContextLookupResult Result = SourceDC.get()->lookup(FromName);
-        for (NamedDecl *FromD : Result) {
-          FilterFoundDecl(std::make_pair(FromD, IP.Forward.get()));
-        }
-      });
+  ForEachMatchingDC(DC, [&](ASTImporter &Forward, ASTImporter &Reverse,
+                            Source<const DeclContext *> SourceDC) -> bool {
+    DeclarationName FromName = Reverse.Import(Name);
+    DeclContextLookupResult Result = SourceDC.get()->lookup(FromName);
+    for (NamedDecl *FromD : Result) {
+      FilterFoundDecl(std::make_pair(FromD, &Forward));
+    }
+    return false;
+  });
 
-  llvm::ArrayRef<Candidate> DeclsToReport =
-      CompleteDecls.empty() ? ForwardDecls : CompleteDecls;
-
-  if (DeclsToReport.empty()) {
+  if (Candidates.empty()) {
     return false;
   }
 
-  Decls.reserve(DeclsToReport.size());
-  for (const Candidate &C : DeclsToReport) {
+  Decls.reserve(Candidates.size());
+  for (const Candidate &C : Candidates) {
     NamedDecl *d = cast<NamedDecl>(C.second->Import(C.first.get()));
     assert(d);
     Decls.push_back(d);
@@ -170,17 +283,15 @@
 void ExternalASTMerger::FindExternalLexicalDecls(
     const DeclContext *DC, llvm::function_ref<bool(Decl::Kind)> IsKindWeWant,
     SmallVectorImpl<Decl *> &Result) {
-  ForEachMatchingDC(
-      DC, Importers,
-      [&](const ImporterPair &IP, Source<const DeclContext *> SourceDC) {
-        for (const Decl *SourceDecl : SourceDC.get()->decls()) {
-          if (IsKindWeWant(SourceDecl->getKind())) {
-            Decl *ImportedDecl =
-                IP.Forward->Import(const_cast<Decl *>(SourceDecl));
-            assert(ImportedDecl->getDeclContext() == DC);
-            (void)ImportedDecl;
-          }
-        }
-      });
+  ForEachMatchingDC(DC, [&](ASTImporter &Forward, ASTImporter &Reverse,
+                            Source<const DeclContext *> SourceDC) -> bool {
+    for (const Decl *SourceDecl : SourceDC.get()->decls()) {
+      if (IsKindWeWant(SourceDecl->getKind())) {
+        Decl *ImportedDecl = Forward.Import(const_cast<Decl *>(SourceDecl));
+        assert(!ImportedDecl || IsSameDC(ImportedDecl->getDeclContext(), DC));
+        (void)ImportedDecl;
+      }
+    }
+    return false;
+  });
 }
-
Index: lib/Sema/SemaType.cpp
===================================================================
--- lib/Sema/SemaType.cpp
+++ lib/Sema/SemaType.cpp
@@ -7303,11 +7303,15 @@
 
     // Give the external AST source a chance to complete the type.
     if (auto *Source = Context.getExternalSource()) {
-      if (Tag)
-        Source->CompleteType(Tag->getDecl());
-      else
-        Source->CompleteType(IFace->getDecl());
-
+      if (Tag) {
+        TagDecl *TagD = Tag->getDecl();
+        if (TagD->hasExternalLexicalStorage())
+          Source->CompleteType(TagD);
+      } else {
+        ObjCInterfaceDecl *IFaceD = IFace->getDecl();
+        if (IFaceD->hasExternalLexicalStorage())
+          Source->CompleteType(IFace->getDecl());
+      }
       // If the external source completed the type, go through the motions
       // again to ensure we're allowed to use the completed type.
       if (!T->isIncompleteType())
Index: test/Import/extern-c-function/Inputs/F.cpp
===================================================================
--- test/Import/extern-c-function/Inputs/F.cpp
+++ test/Import/extern-c-function/Inputs/F.cpp
@@ -1 +1,3 @@
-void f(int arg) { }
+extern "C" {
+  void f(int arg);
+}
Index: test/Import/extern-c-function/test.cpp
===================================================================
--- test/Import/extern-c-function/test.cpp
+++ test/Import/extern-c-function/test.cpp
@@ -1,7 +1,4 @@
-// RUN: clang-import-test -import %S/Inputs/F1.c -import %S/Inputs/F2.c -expression %s
+// RUN: clang-import-test -import %S/Inputs/F.cpp -expression %s
 void expr() {
   f(2);
-  f("world");
-  S s;
-  f(s);
-}
+}
\ No newline at end of file
Index: test/Import/forward-declared-objc-class/Inputs/S1.m
===================================================================
--- test/Import/forward-declared-objc-class/Inputs/S1.m
+++ test/Import/forward-declared-objc-class/Inputs/S1.m
@@ -1 +1 @@
-struct S;
+@class MyClass;
\ No newline at end of file
Index: test/Import/forward-declared-objc-class/Inputs/S2.m
===================================================================
--- test/Import/forward-declared-objc-class/Inputs/S2.m
+++ test/Import/forward-declared-objc-class/Inputs/S2.m
@@ -1,3 +1,6 @@
-struct S {
-  int a;
+@interface MyClass {
+  int j;
 };
++(MyClass*)fromInteger:(int)_j;
+-(int)getInteger;
+@end
\ No newline at end of file
Index: test/Import/forward-declared-objc-class/Inputs/S3.m
===================================================================
--- test/Import/forward-declared-objc-class/Inputs/S3.m
+++ test/Import/forward-declared-objc-class/Inputs/S3.m
@@ -1 +1 @@
-struct S;
+@class MyClass;
\ No newline at end of file
Index: test/Import/forward-declared-objc-class/test.m
===================================================================
--- test/Import/forward-declared-objc-class/test.m
+++ test/Import/forward-declared-objc-class/test.m
@@ -1,5 +1,6 @@
-// RUN: clang-import-test -import %S/Inputs/S1.c --import %S/Inputs/S2.c -expression %s
+// RUN: clang-import-test -x objective-c++ -import %S/Inputs/S1.m --import %S/Inputs/S2.m --import %S/Inputs/S3.m -expression %s
 void expr() {
-  struct S MyS;
-  MyS.a = 3;
+  MyClass *c = [MyClass fromInteger:3];
+  const int i = [c getInteger];
+  const int j = c->j;
 }
Index: test/Import/forward-declared-struct/test.c
===================================================================
--- test/Import/forward-declared-struct/test.c
+++ test/Import/forward-declared-struct/test.c
@@ -1,4 +1,4 @@
-// RUN: clang-import-test -import %S/Inputs/S1.c --import %S/Inputs/S2.c -expression %s
+// RUN: clang-import-test -import %S/Inputs/S1.c --import %S/Inputs/S2.c --import %S/Inputs/S3.c -expression %s
 void expr() {
   struct S MyS;
   MyS.a = 3;
Index: test/Import/local-struct-use-origins/test.cpp
===================================================================
--- test/Import/local-struct-use-origins/test.cpp
+++ test/Import/local-struct-use-origins/test.cpp
@@ -1,7 +1,6 @@
-// RUN: clang-import-test -dump-ir -import %S/Inputs/Callee.cpp -expression %s | FileCheck %s
-// XFAIL: *
+// RUN: clang-import-test -dump-ir -use-origins -import %S/Inputs/Callee.cpp -expression %s | FileCheck %s
 // CHECK: %struct.S = type { i
-// CHECK: %struct.S.0 = type { i1 }
+// CHECK: %struct.S.0 = type { i
 
 void foo() {
   return Bar().bar(3, true);
Index: test/Import/local-struct/test.cpp
===================================================================
--- test/Import/local-struct/test.cpp
+++ test/Import/local-struct/test.cpp
@@ -1,7 +1,6 @@
 // RUN: clang-import-test -dump-ir -import %S/Inputs/Callee.cpp -expression %s | FileCheck %s
-// XFAIL: *
 // CHECK: %struct.S = type { i
-// CHECK: %struct.S.0 = type { i1 }
+// CHECK: %struct.S.0 = type { i
 
 void foo() {
   return Bar().bar(3, true);
Index: test/Import/objc-definitions-in-expression/test.m
===================================================================
--- test/Import/objc-definitions-in-expression/test.m
+++ test/Import/objc-definitions-in-expression/test.m
@@ -1,5 +1,21 @@
 // RUN: clang-import-test -x objective-c++ -import %S/Inputs/S.m -expression %s
+@class D;
+
+@interface B {
+  int x;
+  int y;
+}
+@end
+
+@interface D : B {
+  int z;
+}
+-(int)n;
+@end
+
 void expr() {
   C *c;
   int i = [c m];
+  D *d;
+  int j = [d n] + d->x;
 }
Index: test/Import/struct-and-var/Inputs/S1.cpp
===================================================================
--- test/Import/struct-and-var/Inputs/S1.cpp
+++ test/Import/struct-and-var/Inputs/S1.cpp
@@ -1,6 +1 @@
-class T;
-
-class S {
-  T *t;
-  int a;
-};
+int F;
Index: test/Import/struct-and-var/Inputs/S2.cpp
===================================================================
--- test/Import/struct-and-var/Inputs/S2.cpp
+++ test/Import/struct-and-var/Inputs/S2.cpp
@@ -1,7 +1,3 @@
-class U {
-  int b;
+struct F {
+  int a;
 };
-
-class T {
-  U u;
-};
Index: test/Import/struct-and-var/test.cpp
===================================================================
--- test/Import/struct-and-var/test.cpp
+++ test/Import/struct-and-var/test.cpp
@@ -1,7 +1,5 @@
 // RUN: clang-import-test --import %S/Inputs/S1.cpp --import %S/Inputs/S2.cpp -expression %s
 void expr() {
-  S MyS;
-  T MyT;
-  MyS.a = 3;
-  MyT.u.b = 2;
+  struct F f;
+  int x = f.a;
 }
Index: test/Import/template/Inputs/T.cpp
===================================================================
--- test/Import/template/Inputs/T.cpp
+++ test/Import/template/Inputs/T.cpp
@@ -1,14 +1,5 @@
 template <typename T> struct A {
-};
-
-template <> struct A<int> {
   struct B {
-    int f;
+    T f;
   };
 };
-
-template <> struct A<bool> {
-  struct B {
-    int g;
-  };
-};
Index: test/Import/template/test.cpp
===================================================================
--- test/Import/template/test.cpp
+++ test/Import/template/test.cpp
@@ -1,7 +1,4 @@
 // RUN: clang-import-test -import %S/Inputs/T.cpp -expression %s
-// XFAIL: *
 void expr() {
-  A<int>::B b1;
-  A<bool>::B b2;
-  b1.f + b2.g;
+  A<int>::B b;
 }
Index: tools/clang-import-test/clang-import-test.cpp
===================================================================
--- tools/clang-import-test/clang-import-test.cpp
+++ tools/clang-import-test/clang-import-test.cpp
@@ -48,8 +48,12 @@
 
 static llvm::cl::opt<bool>
     Direct("direct", llvm::cl::Optional,
-             llvm::cl::desc("Use the parsed declarations without indirection"));
+           llvm::cl::desc("Use the parsed declarations without indirection"));
 
+static llvm::cl::opt<bool>
+    UseOrigins("use-origins", llvm::cl::Optional,
+           llvm::cl::desc("Use DeclContext origin information for more accurate lookups"));  
+
 static llvm::cl::list<std::string>
     ClangArgs("Xcc", llvm::cl::ZeroOrMore,
               llvm::cl::desc("Argument to pass to the CompilerInvocation"),
@@ -60,13 +64,11 @@
           llvm::cl::desc("The language to parse (default: c++)"),
           llvm::cl::init("c++"));
 
-static llvm::cl::opt<bool>
-DumpAST("dump-ast", llvm::cl::init(false),
-        llvm::cl::desc("Dump combined AST"));
+static llvm::cl::opt<bool> DumpAST("dump-ast", llvm::cl::init(false),
+                                   llvm::cl::desc("Dump combined AST"));
 
-static llvm::cl::opt<bool>
-DumpIR("dump-ir", llvm::cl::init(false),
-        llvm::cl::desc("Dump IR from final parse"));
+static llvm::cl::opt<bool> DumpIR("dump-ir", llvm::cl::init(false),
+                                  llvm::cl::desc("Dump IR from final parse"));
 
 namespace init_convenience {
 class TestDiagnosticConsumer : public DiagnosticConsumer {
@@ -154,8 +156,7 @@
   }
 };
 
-std::unique_ptr<CompilerInstance>
-BuildCompilerInstance() {
+std::unique_ptr<CompilerInstance> BuildCompilerInstance() {
   auto Ins = llvm::make_unique<CompilerInstance>();
   auto DC = llvm::make_unique<TestDiagnosticConsumer>();
   const bool ShouldOwnClient = true;
@@ -227,29 +228,48 @@
 } // end namespace
 
 namespace {
- 
-void AddExternalSource(
-    CompilerInstance &CI,
-    llvm::ArrayRef<std::unique_ptr<CompilerInstance>> Imports) {
-  ExternalASTMerger::ImporterEndpoint Target({CI.getASTContext(), CI.getFileManager()});
-  llvm::SmallVector<ExternalASTMerger::ImporterEndpoint, 3> Sources;
-  for (const std::unique_ptr<CompilerInstance> &CI : Imports) {
-    Sources.push_back({CI->getASTContext(), CI->getFileManager()});
+
+struct CIAndOrigins {
+  using OriginMap = clang::ExternalASTMerger::OriginMap;
+  std::unique_ptr<CompilerInstance> CI;
+
+  ASTContext &getASTContext() { return CI->getASTContext(); }
+  FileManager &getFileManager() { return CI->getFileManager(); }
+  const OriginMap &getOriginMap() {
+    static const OriginMap EmptyOriginMap;
+    if (ExternalASTSource *Source = CI->getASTContext().getExternalSource())
+      return static_cast<ExternalASTMerger *>(Source)->GetOrigins();
+    else
+      return EmptyOriginMap;
   }
+  DiagnosticConsumer &getDiagnosticClient() {
+    return CI->getDiagnosticClient();
+  }
+  CompilerInstance &getCompilerInstance() { return *CI; }
+};
+
+void AddExternalSource(CIAndOrigins &CI,
+                       llvm::MutableArrayRef<CIAndOrigins> Imports) {
+  ExternalASTMerger::ImporterTarget Target(
+      {CI.getASTContext(), CI.getFileManager()});
+  llvm::SmallVector<ExternalASTMerger::ImporterSource, 3> Sources;
+  for (CIAndOrigins &Import : Imports) {
+    Sources.push_back(
+        {Import.getASTContext(), Import.getFileManager(), Import.getOriginMap()});
+  }
   auto ES = llvm::make_unique<ExternalASTMerger>(Target, Sources);
   CI.getASTContext().setExternalSource(ES.release());
   CI.getASTContext().getTranslationUnitDecl()->setHasExternalVisibleStorage();
 }
 
-std::unique_ptr<CompilerInstance> BuildIndirect(std::unique_ptr<CompilerInstance> &CI) {
-  std::unique_ptr<CompilerInstance> IndirectCI =
-      init_convenience::BuildCompilerInstance();
+CIAndOrigins BuildIndirect(CIAndOrigins &CI) {
+  CIAndOrigins IndirectCI{init_convenience::BuildCompilerInstance()};
   auto ST = llvm::make_unique<SelectorTable>();
   auto BC = llvm::make_unique<Builtin::Context>();
-  std::unique_ptr<ASTContext> AST =
-      init_convenience::BuildASTContext(*IndirectCI, *ST, *BC);
-  IndirectCI->setASTContext(AST.release());
-  AddExternalSource(*IndirectCI, CI);
+  std::unique_ptr<ASTContext> AST = init_convenience::BuildASTContext(
+      IndirectCI.getCompilerInstance(), *ST, *BC);
+  IndirectCI.getCompilerInstance().setASTContext(AST.release());
+  AddExternalSource(IndirectCI, CI);
   return IndirectCI;
 }
 
@@ -266,41 +286,41 @@
   return llvm::Error::success();
 }
 
-llvm::Expected<std::unique_ptr<CompilerInstance>>
-Parse(const std::string &Path,
-      llvm::ArrayRef<std::unique_ptr<CompilerInstance>> Imports,
-      bool ShouldDumpAST, bool ShouldDumpIR) {
-  std::unique_ptr<CompilerInstance> CI =
-      init_convenience::BuildCompilerInstance();
+llvm::Expected<CIAndOrigins> Parse(const std::string &Path,
+                                   llvm::MutableArrayRef<CIAndOrigins> Imports,
+                                   bool ShouldDumpAST, bool ShouldDumpIR) {
+  CIAndOrigins CI{init_convenience::BuildCompilerInstance()};
   auto ST = llvm::make_unique<SelectorTable>();
   auto BC = llvm::make_unique<Builtin::Context>();
   std::unique_ptr<ASTContext> AST =
-      init_convenience::BuildASTContext(*CI, *ST, *BC);
-  CI->setASTContext(AST.release());
+      init_convenience::BuildASTContext(CI.getCompilerInstance(), *ST, *BC);
+  CI.getCompilerInstance().setASTContext(AST.release());
   if (Imports.size())
-    AddExternalSource(*CI, Imports);
+    AddExternalSource(CI, Imports);
 
   std::vector<std::unique_ptr<ASTConsumer>> ASTConsumers;
 
   auto LLVMCtx = llvm::make_unique<llvm::LLVMContext>();
-  ASTConsumers.push_back(init_convenience::BuildCodeGen(*CI, *LLVMCtx));
-  auto &CG = *static_cast<CodeGenerator*>(ASTConsumers.back().get());
+  ASTConsumers.push_back(
+      init_convenience::BuildCodeGen(CI.getCompilerInstance(), *LLVMCtx));
+  auto &CG = *static_cast<CodeGenerator *>(ASTConsumers.back().get());
 
   if (ShouldDumpAST)
     ASTConsumers.push_back(CreateASTDumper("", true, false, false));
 
-  CI->getDiagnosticClient().BeginSourceFile(CI->getLangOpts(),
-                                            &CI->getPreprocessor());
+  CI.getDiagnosticClient().BeginSourceFile(
+      CI.getCompilerInstance().getLangOpts(),
+      &CI.getCompilerInstance().getPreprocessor());
   MultiplexConsumer Consumers(std::move(ASTConsumers));
-  Consumers.Initialize(CI->getASTContext());
+  Consumers.Initialize(CI.getASTContext());
 
-  if (llvm::Error PE = ParseSource(Path, *CI, Consumers)) {
+  if (llvm::Error PE = ParseSource(Path, CI.getCompilerInstance(), Consumers)) {
     return std::move(PE);
   }
-  CI->getDiagnosticClient().EndSourceFile();
+  CI.getDiagnosticClient().EndSourceFile();
   if (ShouldDumpIR)
     CG.GetModule()->print(llvm::outs(), nullptr);
-  if (CI->getDiagnosticClient().getNumErrors()) {
+  if (CI.getDiagnosticClient().getNumErrors()) {
     return llvm::make_error<llvm::StringError>(
         "Errors occured while parsing the expression.", std::error_code());
   } else {
@@ -314,10 +334,9 @@
   const bool DisableCrashReporting = true;
   llvm::sys::PrintStackTraceOnErrorSignal(argv[0], DisableCrashReporting);
   llvm::cl::ParseCommandLineOptions(argc, argv);
-  std::vector<std::unique_ptr<CompilerInstance>> ImportCIs;
+  std::vector<CIAndOrigins> ImportCIs;
   for (auto I : Imports) {
-    llvm::Expected<std::unique_ptr<CompilerInstance>> ImportCI =
-      Parse(I, {}, false, false);
+    llvm::Expected<CIAndOrigins> ImportCI = Parse(I, {}, false, false);
     if (auto E = ImportCI.takeError()) {
       llvm::errs() << llvm::toString(std::move(E));
       exit(-1);
@@ -325,15 +344,21 @@
       ImportCIs.push_back(std::move(*ImportCI));
     }
   }
-  std::vector<std::unique_ptr<CompilerInstance>> IndirectCIs;
-  if (!Direct) {
+  std::vector<CIAndOrigins> IndirectCIs;
+  if (!Direct || UseOrigins) {
     for (auto &ImportCI : ImportCIs) {
-      std::unique_ptr<CompilerInstance> IndirectCI = BuildIndirect(ImportCI);
+      CIAndOrigins IndirectCI = BuildIndirect(ImportCI);
       IndirectCIs.push_back(std::move(IndirectCI));
     }
   }
-  llvm::Expected<std::unique_ptr<CompilerInstance>> ExpressionCI =
-      Parse(Expression, Direct ? ImportCIs : IndirectCIs, DumpAST, DumpIR);
+  if (UseOrigins) {
+    for (auto &ImportCI : ImportCIs) {
+      IndirectCIs.push_back(std::move(ImportCI));
+    }
+  }
+  llvm::Expected<CIAndOrigins> ExpressionCI =
+      Parse(Expression, (Direct && !UseOrigins) ? ImportCIs : IndirectCIs,
+            DumpAST, DumpIR);
   if (auto E = ExpressionCI.takeError()) {
     llvm::errs() << llvm::toString(std::move(E));
     exit(-1);
@@ -341,4 +366,3 @@
     return 0;
   }
 }
-