diff --git a/clang/lib/AST/DeclBase.cpp b/clang/lib/AST/DeclBase.cpp
index 9171d2792c0e..2e275cfab1ee 100644
--- a/clang/lib/AST/DeclBase.cpp
+++ b/clang/lib/AST/DeclBase.cpp
@@ -1084,6 +1084,9 @@ void DeclContext::addDeclInternal(Decl *D) {
 
 DeclContext::lookup_result
 DeclContext::lookup(DeclarationName Name) {
+  assert(DeclKind != Decl::LinkageSpec &&
+         "Should not perform lookups into linkage specs!");
+
   DeclContext *PrimaryContext = getPrimaryContext();
   if (PrimaryContext != this)
     return PrimaryContext->lookup(Name);
diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
index fbb0dc6b0f90..0382a835489f 100644
--- a/clang/lib/Sema/SemaLookup.cpp
+++ b/clang/lib/Sema/SemaLookup.cpp
@@ -106,14 +106,15 @@ namespace {
       assert(InnermostFileDC && InnermostFileDC->isFileContext());
 
       for (; S; S = S->getParent()) {
+        // C++ [namespace.udir]p1:
+        //   A using-directive shall not appear in class scope, but may
+        //   appear in namespace scope or in block scope.
         DeclContext *Ctx = static_cast<DeclContext*>(S->getEntity());
-        if (Ctx && !Ctx->isFunctionOrMethod()) {
-          DeclContext *EffectiveDC = (Ctx->isFileContext() ? Ctx : InnermostFileDC);
-          visit(Ctx, EffectiveDC);
-        } else {
+        if (Ctx && Ctx->isFileContext()) {
+          visit(Ctx, Ctx);
+        } else if (!Ctx || Ctx->isFunctionOrMethod()) {
           Scope::udir_iterator I = S->using_directives_begin(),
                              End = S->using_directives_end();
-
           for (; I != End; ++I)
             visit(*I, InnermostFileDC);
         }
diff --git a/clang/lib/Serialization/ASTWriter.cpp b/clang/lib/Serialization/ASTWriter.cpp
index cb3206844260..a6cccbf4b54c 100644
--- a/clang/lib/Serialization/ASTWriter.cpp
+++ b/clang/lib/Serialization/ASTWriter.cpp
@@ -2792,10 +2792,6 @@ uint64_t ASTWriter::WriteDeclContextVisibleBlock(ASTContext &Context,
   if (DC->isTranslationUnit() && !Context.getLangOpts().CPlusPlus)
     return 0;
 
-  // Force the DeclContext to build a its name-lookup table.
-  if (!DC->hasExternalVisibleStorage())
-    DC->lookup(DeclarationName());
-
   // Serialize the contents of the mapping used for lookup. Note that,
   // although we have two very different code paths, the serialized
   // representation is the same for both cases: a declaration name,