diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index a5b43e8..a79b000 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -2365,7 +2365,7 @@
   virtual OwningExprResult ActOnFinishFullExpr(ExprArg Expr);
 
   // Marks SS invalid if it represents an incomplete type.
-  bool RequireCompleteDeclContext(CXXScopeSpec &SS);
+  bool RequireCompleteDeclContext(CXXScopeSpec &SS, DeclContext *DC);
 
   DeclContext *computeDeclContext(QualType T);
   DeclContext *computeDeclContext(const CXXScopeSpec &SS,
diff --git a/lib/Sema/SemaCXXScopeSpec.cpp b/lib/Sema/SemaCXXScopeSpec.cpp
index 10adc67..c0ec9e9 100644
--- a/lib/Sema/SemaCXXScopeSpec.cpp
+++ b/lib/Sema/SemaCXXScopeSpec.cpp
@@ -186,21 +186,10 @@
 /// that is currently being defined. Or, if we have a type that names
 /// a class template specialization that is not a complete type, we
 /// will attempt to instantiate that class template.
-bool Sema::RequireCompleteDeclContext(CXXScopeSpec &SS) {
-  if (!SS.isSet() || SS.isInvalid())
-    return false;
+bool Sema::RequireCompleteDeclContext(CXXScopeSpec &SS,
+                                      DeclContext *DC) {
+  assert(DC != 0 && "given null context");
 
-  DeclContext *DC = computeDeclContext(SS, true);
-  if (!DC) {
-    // It's dependent.
-    assert(isDependentScopeSpecifier(SS) && 
-           "No context for non-dependent scope specifier?");
-    Diag(SS.getRange().getBegin(), diag::err_dependent_nested_name_spec)
-      << SS.getRange();
-    SS.setScopeRep(0);
-    return true;
-  }
-  
   if (TagDecl *Tag = dyn_cast<TagDecl>(DC)) {
     // If this is a dependent type, then we consider it complete.
     if (Tag->isDependentContext())
@@ -216,7 +205,7 @@
     if (RequireCompleteType(SS.getRange().getBegin(),
                             Context.getTypeDeclType(Tag),
                             PDiag(diag::err_incomplete_nested_name_spec)
-                            << SS.getRange())) {
+                              << SS.getRange())) {
       SS.setScopeRep(0);  // Mark the ScopeSpec invalid.
       return true;
     }
@@ -322,7 +311,8 @@
     // nested-name-specifier.
     
     // The declaration context must be complete.
-    if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(SS))
+    if (!LookupCtx->isDependentContext() &&
+        RequireCompleteDeclContext(SS, LookupCtx))
       return false;
     
     LookupQualifiedName(Found, LookupCtx);
@@ -392,7 +382,8 @@
     // nested-name-specifier.
 
     // The declaration context must be complete.
-    if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(SS))
+    if (!LookupCtx->isDependentContext() &&
+        RequireCompleteDeclContext(SS, LookupCtx))
       return 0;
 
     LookupQualifiedName(Found, LookupCtx);
@@ -656,7 +647,7 @@
 
   // Before we enter a declarator's context, we need to make sure that
   // it is a complete declaration context.
-  if (!DC->isDependentContext() && RequireCompleteDeclContext(SS))
+  if (!DC->isDependentContext() && RequireCompleteDeclContext(SS, DC))
     return true;
     
   EnterDeclaratorContext(S, DC);
diff --git a/lib/Sema/SemaCodeComplete.cpp b/lib/Sema/SemaCodeComplete.cpp
index 35bb697..c075d16 100644
--- a/lib/Sema/SemaCodeComplete.cpp
+++ b/lib/Sema/SemaCodeComplete.cpp
@@ -2286,7 +2286,7 @@
 
   // Try to instantiate any non-dependent declaration contexts before
   // we look in them.
-  if (!isDependentScopeSpecifier(SS) && RequireCompleteDeclContext(SS))
+  if (!isDependentScopeSpecifier(SS) && RequireCompleteDeclContext(SS, Ctx))
     return;
 
   ResultBuilder Results(*this);
diff --git a/lib/Sema/SemaDecl.cpp b/lib/Sema/SemaDecl.cpp
index 7a70c32..3e4c923 100644
--- a/lib/Sema/SemaDecl.cpp
+++ b/lib/Sema/SemaDecl.cpp
@@ -97,7 +97,8 @@
       return 0;
     }
     
-    if (!LookupCtx->isDependentContext() && RequireCompleteDeclContext(*SS))
+    if (!LookupCtx->isDependentContext() &&
+        RequireCompleteDeclContext(*SS, LookupCtx))
       return 0;
   }
 
@@ -2030,7 +2031,7 @@
     bool IsDependentContext = DC->isDependentContext();
 
     if (!IsDependentContext && 
-        RequireCompleteDeclContext(D.getCXXScopeSpec()))
+        RequireCompleteDeclContext(D.getCXXScopeSpec(), DC))
       return DeclPtrTy();
 
     if (isa<CXXRecordDecl>(DC) && !cast<CXXRecordDecl>(DC)->hasDefinition()) {
@@ -4940,12 +4941,18 @@
         IsDependent = true;
         return DeclPtrTy();
       }
+    } else {
+      DC = computeDeclContext(SS, true);
+      if (!DC) {
+        Diag(SS.getRange().getBegin(), diag::err_dependent_nested_name_spec)
+          << SS.getRange();
+        return DeclPtrTy();
+      }
     }
 
-    if (RequireCompleteDeclContext(SS))
+    if (RequireCompleteDeclContext(SS, DC))
       return DeclPtrTy::make((Decl *)0);
 
-    DC = computeDeclContext(SS, true);
     SearchDC = DC;
     // Look-up name inside 'foo::'.
     LookupQualifiedName(Previous, DC);
diff --git a/lib/Sema/SemaDeclCXX.cpp b/lib/Sema/SemaDeclCXX.cpp
index 854f204..c73c6ca 100644
--- a/lib/Sema/SemaDeclCXX.cpp
+++ b/lib/Sema/SemaDeclCXX.cpp
@@ -3724,7 +3724,7 @@
   if (!LookupContext) return D;
   UsingDecl *UD = cast<UsingDecl>(D);
 
-  if (RequireCompleteDeclContext(SS)) {
+  if (RequireCompleteDeclContext(SS, LookupContext)) {
     UD->setInvalidDecl();
     return UD;
   }
@@ -5251,11 +5251,11 @@
   LookupResult Previous(*this, Name, D.getIdentifierLoc(), LookupOrdinaryName,
                         ForRedeclaration);
   if (!ScopeQual.isInvalid() && ScopeQual.isSet()) {
-    // FIXME: RequireCompleteDeclContext
     DC = computeDeclContext(ScopeQual);
 
     // FIXME: handle dependent contexts
     if (!DC) return DeclPtrTy();
+    if (RequireCompleteDeclContext(ScopeQual, DC)) return DeclPtrTy();
 
     LookupQualifiedName(Previous, DC);
 
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index d8d525e..a1b66cd 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -1238,7 +1238,7 @@
   if (!(DC = computeDeclContext(SS, false)) || DC->isDependentContext())
     return BuildDependentDeclRefExpr(SS, Name, NameLoc, 0);
 
-  if (RequireCompleteDeclContext(SS))
+  if (RequireCompleteDeclContext(SS, DC))
     return ExprError();
 
   LookupResult R(*this, Name, NameLoc, LookupOrdinaryName);
@@ -2582,7 +2582,7 @@
     // nested-name-specifier.
     DC = SemaRef.computeDeclContext(SS, false);
 
-    if (SemaRef.RequireCompleteDeclContext(SS)) {
+    if (SemaRef.RequireCompleteDeclContext(SS, DC)) {
       SemaRef.Diag(SS.getRange().getEnd(), diag::err_typecheck_incomplete_tag)
         << SS.getRange() << DC;
       return true;
diff --git a/lib/Sema/SemaLookup.cpp b/lib/Sema/SemaLookup.cpp
index bdbbc11..337a4a3 100644
--- a/lib/Sema/SemaLookup.cpp
+++ b/lib/Sema/SemaLookup.cpp
@@ -1261,7 +1261,7 @@
     if (DeclContext *DC = computeDeclContext(*SS, EnteringContext)) {
       // We have resolved the scope specifier to a particular declaration
       // contex, and will perform name lookup in that context.
-      if (!DC->isDependentContext() && RequireCompleteDeclContext(*SS))
+      if (!DC->isDependentContext() && RequireCompleteDeclContext(*SS, DC))
         return false;
 
       R.setContextRange(SS->getRange());
diff --git a/lib/Sema/SemaTemplate.cpp b/lib/Sema/SemaTemplate.cpp
index 56410a2..694b21c 100644
--- a/lib/Sema/SemaTemplate.cpp
+++ b/lib/Sema/SemaTemplate.cpp
@@ -210,7 +210,7 @@
     isDependent = isDependentScopeSpecifier(SS);
     
     // The declaration context must be complete.
-    if (LookupCtx && RequireCompleteDeclContext(SS))
+    if (LookupCtx && RequireCompleteDeclContext(SS, LookupCtx))
       return;
   }
 
@@ -753,15 +753,15 @@
   LookupResult Previous(*this, Name, NameLoc, LookupOrdinaryName,
                         ForRedeclaration);
   if (SS.isNotEmpty() && !SS.isInvalid()) {
-    if (RequireCompleteDeclContext(SS))
-      return true;
-
     SemanticContext = computeDeclContext(SS, true);
     if (!SemanticContext) {
       // FIXME: Produce a reasonable diagnostic here
       return true;
     }
 
+    if (RequireCompleteDeclContext(SS, SemanticContext))
+      return true;
+
     LookupQualifiedName(Previous, SemanticContext);
   } else {
     SemanticContext = CurContext;
@@ -1633,7 +1633,7 @@
   DeclContext *DC;
   if (!(DC = computeDeclContext(SS, false)) ||
       DC->isDependentContext() ||
-      RequireCompleteDeclContext(SS))
+      RequireCompleteDeclContext(SS, DC))
     return BuildDependentDeclRefExpr(SS, Name, NameLoc, &TemplateArgs);
 
   LookupResult R(*this, Name, NameLoc, LookupOrdinaryName);
@@ -5260,36 +5260,26 @@
 Sema::CheckTypenameType(ElaboratedTypeKeyword Keyword,
                         NestedNameSpecifier *NNS, const IdentifierInfo &II,
                         SourceRange Range) {
-  CXXRecordDecl *CurrentInstantiation = 0;
-  if (NNS->isDependent()) {
-    CurrentInstantiation = getCurrentInstantiationOf(NNS);
+  CXXScopeSpec SS;
+  SS.setScopeRep(NNS);
+  SS.setRange(Range);
 
-    // If the nested-name-specifier does not refer to the current
-    // instantiation, then build a typename type.
-    if (!CurrentInstantiation)
-      return Context.getDependentNameType(Keyword, NNS, &II);
-
-    // The nested-name-specifier refers to the current instantiation, so the
-    // "typename" keyword itself is superfluous. In C++03, the program is
-    // actually ill-formed. However, DR 382 (in C++0x CD1) allows such
-    // extraneous "typename" keywords, and we retroactively apply this DR to
-    // C++03 code.
+  DeclContext *Ctx = computeDeclContext(SS);
+  if (!Ctx) {
+    // If the nested-name-specifier is dependent and couldn't be
+    // resolved to a type, build a typename type.
+    assert(NNS->isDependent());
+    return Context.getDependentNameType(Keyword, NNS, &II);
   }
 
-  DeclContext *Ctx = 0;
+  // If the nested-name-specifier refers to the current instantiation,
+  // the "typename" keyword itself is superfluous. In C++03, the
+  // program is actually ill-formed. However, DR 382 (in C++0x CD1)
+  // allows such extraneous "typename" keywords, and we retroactively
+  // apply this DR to C++03 code.  In any case we continue.
 
-  if (CurrentInstantiation)
-    Ctx = CurrentInstantiation;
-  else {
-    CXXScopeSpec SS;
-    SS.setScopeRep(NNS);
-    SS.setRange(Range);
-    if (RequireCompleteDeclContext(SS))
-      return QualType();
-
-    Ctx = computeDeclContext(SS);
-  }
-  assert(Ctx && "No declaration context?");
+  if (RequireCompleteDeclContext(SS, Ctx))
+    return QualType();
 
   DeclarationName Name(&II);
   LookupResult Result(*this, Name, Range.getEnd(), LookupOrdinaryName);