diff --git a/clang/lib/Sema/SemaDecl.cpp b/clang/lib/Sema/SemaDecl.cpp
@@ -218,7 +218,8 @@ ParsedType Sema::getTypeName(const IdentifierInfo &II, SourceLocation NameLoc,
     if (CorrectedII) {
       TypeNameValidatorCCC Validator(true, isClassName);
       TypoCorrection Correction = CorrectTypo(Result.getLookupNameInfo(),
-                                              Kind, S, SS, Validator);
+                                              Kind, S, SS, Validator,
+                                              CTK_ErrorRecovery);
       IdentifierInfo *NewII = Correction.getCorrectionAsIdentifierInfo();
       TemplateTy Template;
       bool MemberOfUnknownSpecialization;
@@ -408,7 +409,7 @@ bool Sema::DiagnoseUnknownTypeName(IdentifierInfo *&II,
   TypeNameValidatorCCC Validator(false, false, AllowClassTemplates);
   if (TypoCorrection Corrected = CorrectTypo(DeclarationNameInfo(II, IILoc),
                                              LookupOrdinaryName, S, SS,
-                                             Validator)) {
+                                             Validator, CTK_ErrorRecovery)) {
     if (Corrected.isKeyword()) {
       // We corrected to a keyword.
       diagnoseTypo(Corrected, PDiag(diag::err_unknown_typename_suggest) << II);
@@ -650,7 +651,8 @@ Sema::NameClassification Sema::ClassifyName(Scope *S,
       SecondTry = true;
       if (TypoCorrection Corrected = CorrectTypo(Result.getLookupNameInfo(),
                                                  Result.getLookupKind(), S, 
-                                                 &SS, *CCC)) {
+                                                 &SS, *CCC,
+                                                 CTK_ErrorRecovery)) {
         unsigned UnqualifiedDiag = diag::err_undeclared_var_use_suggest;
         unsigned QualifiedDiag = diag::err_no_member_suggest;
 
@@ -1422,7 +1424,7 @@ ObjCInterfaceDecl *Sema::getObjCInterfaceDecl(IdentifierInfo *&Id,
     DeclFilterCCC<ObjCInterfaceDecl> Validator;
     if (TypoCorrection C = CorrectTypo(DeclarationNameInfo(Id, IdLoc),
                                        LookupOrdinaryName, TUScope, NULL,
-                                       Validator)) {
+                                       Validator, CTK_ErrorRecovery)) {
       diagnoseTypo(C, PDiag(diag::err_undef_interface_suggest) << Id);
       IDecl = C.getCorrectionDeclAs<ObjCInterfaceDecl>();
       Id = IDecl->getIdentifier();
@@ -6160,7 +6162,7 @@ static NamedDecl *DiagnoseInvalidRedeclaration(
   } else if ((Correction = SemaRef.CorrectTypo(
                  Prev.getLookupNameInfo(), Prev.getLookupKind(), S,
                  &ExtraArgs.D.getCXXScopeSpec(), Validator,
-                 IsLocalFriend ? 0 : NewDC))) {
+                 Sema::CTK_ErrorRecovery, IsLocalFriend ? 0 : NewDC))) {
     // Set up everything for the call to ActOnFunctionDeclarator
     ExtraArgs.D.SetIdentifier(Correction.getCorrectionAsIdentifierInfo(),
                               ExtraArgs.D.getIdentifierLoc());
@@ -10100,7 +10102,8 @@ NamedDecl *Sema::ImplicitlyDefineFunction(SourceLocation Loc,
     TypoCorrection Corrected;
     DeclFilterCCC<FunctionDecl> Validator;
     if (S && (Corrected = CorrectTypo(DeclarationNameInfo(&II, Loc),
-                                      LookupOrdinaryName, S, 0, Validator)))
+                                      LookupOrdinaryName, S, 0, Validator,
+                                      CTK_NonError)))
       diagnoseTypo(Corrected, PDiag(diag::note_function_suggestion),
                    /*ErrorRecovery*/false);
   }

diff --git a/clang/lib/Sema/SemaDeclCXX.cpp b/clang/lib/Sema/SemaDeclCXX.cpp
@@ -2605,7 +2605,7 @@ Sema::BuildMemInitializer(Decl *ConstructorD,
       MemInitializerValidatorCCC Validator(ClassDecl);
       if (R.empty() && BaseType.isNull() &&
           (Corr = CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(), S, &SS,
-                              Validator, ClassDecl))) {
+                              Validator, CTK_ErrorRecovery, ClassDecl))) {
         if (FieldDecl *Member = Corr.getCorrectionDeclAs<FieldDecl>()) {
           // We have found a non-static data member with a similar
           // name to what was typed; complain and initialize that
@@ -6900,7 +6900,8 @@ static bool TryNamespaceTypoCorrection(Sema &S, LookupResult &R, Scope *Sc,
   R.clear();
   if (TypoCorrection Corrected = S.CorrectTypo(R.getLookupNameInfo(),
                                                R.getLookupKind(), Sc, &SS,
-                                               Validator)) {
+                                               Validator,
+                                               Sema::CTK_ErrorRecovery)) {
     if (DeclContext *DC = S.computeDeclContext(SS, false)) {
       std::string CorrectedStr(Corrected.getAsString(S.getLangOpts()));
       bool DroppedSpecifier = Corrected.WillReplaceSpecifier() &&
@@ -7471,7 +7472,8 @@ NamedDecl *Sema::BuildUsingDeclaration(Scope *S, AccessSpecifier AS,
     UsingValidatorCCC CCC(HasTypenameKeyword, IsInstantiation,
                           CurContext->isRecord());
     if (TypoCorrection Corrected = CorrectTypo(R.getLookupNameInfo(),
-                                               R.getLookupKind(), S, &SS, CCC)){
+                                               R.getLookupKind(), S, &SS, CCC,
+                                               CTK_ErrorRecovery)){
       // We reject any correction for which ND would be NULL.
       NamedDecl *ND = Corrected.getCorrectionDecl();
       R.setLookupName(Corrected.getCorrection());

diff --git a/clang/lib/Sema/SemaDeclObjC.cpp b/clang/lib/Sema/SemaDeclObjC.cpp
@@ -524,7 +524,7 @@ ActOnStartClassInterface(SourceLocation AtInterfaceLoc,
       ObjCInterfaceValidatorCCC Validator(IDecl);
       if (TypoCorrection Corrected = CorrectTypo(
           DeclarationNameInfo(SuperName, SuperLoc), LookupOrdinaryName, TUScope,
-          NULL, Validator)) {
+          NULL, Validator, CTK_ErrorRecovery)) {
         diagnoseTypo(Corrected, PDiag(diag::err_undef_superclass_suggest)
                                     << SuperName << ClassName);
         PrevDecl = Corrected.getCorrectionDeclAs<ObjCInterfaceDecl>();
@@ -794,7 +794,7 @@ Sema::FindProtocolDeclaration(bool WarnOnDeclarations,
       DeclFilterCCC<ObjCProtocolDecl> Validator;
       TypoCorrection Corrected = CorrectTypo(
           DeclarationNameInfo(ProtocolId[i].first, ProtocolId[i].second),
-          LookupObjCProtocolName, TUScope, NULL, Validator);
+          LookupObjCProtocolName, TUScope, NULL, Validator, CTK_ErrorRecovery);
       if ((PDecl = Corrected.getCorrectionDeclAs<ObjCProtocolDecl>()))
         diagnoseTypo(Corrected, PDiag(diag::err_undeclared_protocol_suggest)
                                     << ProtocolId[i].first);
@@ -1034,7 +1034,8 @@ Decl *Sema::ActOnStartClassImplementation(
     ObjCInterfaceValidatorCCC Validator;
     TypoCorrection Corrected =
             CorrectTypo(DeclarationNameInfo(ClassName, ClassLoc),
-                        LookupOrdinaryName, TUScope, NULL, Validator);
+                        LookupOrdinaryName, TUScope, NULL, Validator,
+                        CTK_NonError);
     if (Corrected.getCorrectionDeclAs<ObjCInterfaceDecl>()) {
       // Suggest the (potentially) correct interface name. Don't provide a
       // code-modification hint or use the typo name for recovery, because

diff --git a/clang/lib/Sema/SemaExpr.cpp b/clang/lib/Sema/SemaExpr.cpp
@@ -1843,7 +1843,7 @@ bool Sema::DiagnoseEmptyLookup(Scope *S, CXXScopeSpec &SS, LookupResult &R,
   // We didn't find anything, so try to correct for a typo.
   TypoCorrection Corrected;
   if (S && (Corrected = CorrectTypo(R.getLookupNameInfo(), R.getLookupKind(),
-                                    S, &SS, CCC))) {
+                                    S, &SS, CCC, CTK_ErrorRecovery))) {
     std::string CorrectedStr(Corrected.getAsString(getLangOpts()));
     bool DroppedSpecifier =
         Corrected.WillReplaceSpecifier() && Name.getAsString() == CorrectedStr;
@@ -4004,7 +4004,8 @@ static TypoCorrection TryTypoCorrectionForCall(Sema &S, Expr *Fn,
 
   if (TypoCorrection Corrected = S.CorrectTypo(
           DeclarationNameInfo(FuncName, NameLoc), Sema::LookupOrdinaryName,
-          S.getScopeForContext(S.CurContext), NULL, CCC)) {
+          S.getScopeForContext(S.CurContext), NULL, CCC,
+          Sema::CTK_ErrorRecovery)) {
     if (NamedDecl *ND = Corrected.getCorrectionDecl()) {
       if (Corrected.isOverloaded()) {
         OverloadCandidateSet OCS(NameLoc, OverloadCandidateSet::CSK_Normal);

diff --git a/clang/lib/Sema/SemaExprMember.cpp b/clang/lib/Sema/SemaExprMember.cpp
@@ -627,7 +627,8 @@ LookupMemberExprInRecord(Sema &SemaRef, LookupResult &R,
   RecordMemberExprValidatorCCC Validator(RTy);
   TypoCorrection Corrected = SemaRef.CorrectTypo(R.getLookupNameInfo(),
                                                  R.getLookupKind(), NULL,
-                                                 &SS, Validator, DC);
+                                                 &SS, Validator,
+                                                 Sema::CTK_ErrorRecovery, DC);
   R.clear();
   if (Corrected.isResolved() && !Corrected.isKeyword()) {
     R.setLookupName(Corrected.getCorrection());
@@ -1270,7 +1271,8 @@ Sema::LookupMemberExpr(LookupResult &R, ExprResult &BaseExpr,
       Validator.IsObjCIvarLookup = IsArrow;
       if (TypoCorrection Corrected = CorrectTypo(R.getLookupNameInfo(),
                                                  LookupMemberName, NULL, NULL,
-                                                 Validator, IDecl)) {
+                                                 Validator, CTK_ErrorRecovery,
+                                                 IDecl)) {
         IV = Corrected.getCorrectionDeclAs<ObjCIvarDecl>();
         diagnoseTypo(Corrected,
                      PDiag(diag::err_typecheck_member_reference_ivar_suggest)

diff --git a/clang/lib/Sema/SemaExprObjC.cpp b/clang/lib/Sema/SemaExprObjC.cpp
@@ -1669,7 +1669,7 @@ HandleExprPropertyRefExpr(const ObjCObjectPointerType *OPT,
   DeclFilterCCC<ObjCPropertyDecl> Validator;
   if (TypoCorrection Corrected = CorrectTypo(
           DeclarationNameInfo(MemberName, MemberLoc), LookupOrdinaryName, NULL,
-          NULL, Validator, IFace, false, OPT)) {
+          NULL, Validator, CTK_ErrorRecovery, IFace, false, OPT)) {
     diagnoseTypo(Corrected, PDiag(diag::err_property_not_found_suggest)
                               << MemberName << QualType(OPT, 0));
     DeclarationName TypoResult = Corrected.getCorrection();
@@ -1901,7 +1901,8 @@ Sema::ObjCMessageKind Sema::getObjCMessageKind(Scope *S,
   ObjCInterfaceOrSuperCCC Validator(getCurMethodDecl());
   if (TypoCorrection Corrected =
           CorrectTypo(Result.getLookupNameInfo(), Result.getLookupKind(), S,
-                      NULL, Validator, NULL, false, NULL, false)) {
+                      NULL, Validator, CTK_ErrorRecovery, NULL, false, NULL,
+                      false)) {
     if (Corrected.isKeyword()) {
       // If we've found the keyword "super" (the only keyword that would be
       // returned by CorrectTypo), this is a send to super.

diff --git a/clang/lib/Sema/SemaInit.cpp b/clang/lib/Sema/SemaInit.cpp
@@ -1816,7 +1816,7 @@ InitListChecker::CheckDesignatedInitializer(const InitializedEntity &Entity,
         if (TypoCorrection Corrected = SemaRef.CorrectTypo(
                 DeclarationNameInfo(FieldName, D->getFieldLoc()),
                 Sema::LookupMemberName, /*Scope=*/ 0, /*SS=*/ 0, Validator,
-                RT->getDecl())) {
+                Sema::CTK_ErrorRecovery, RT->getDecl())) {
           SemaRef.diagnoseTypo(
               Corrected,
               SemaRef.PDiag(diag::err_field_designator_unknown_suggest)

diff --git a/clang/lib/Sema/SemaLookup.cpp b/clang/lib/Sema/SemaLookup.cpp
@@ -23,6 +23,9 @@
 #include "clang/AST/ExprCXX.h"
 #include "clang/Basic/Builtins.h"
 #include "clang/Basic/LangOptions.h"
+#include "clang/Lex/HeaderSearch.h"
+#include "clang/Lex/ModuleLoader.h"
+#include "clang/Lex/Preprocessor.h"
 #include "clang/Sema/DeclSpec.h"
 #include "clang/Sema/ExternalSemaSource.h"
 #include "clang/Sema/Overload.h"
@@ -32,6 +35,8 @@
 #include "clang/Sema/SemaInternal.h"
 #include "clang/Sema/TemplateDeduction.h"
 #include "clang/Sema/TypoCorrection.h"
+#include "clang/Serialization/GlobalModuleIndex.h"
+#include "clang/Serialization/Module.h"
 #include "llvm/ADT/STLExtras.h"
 #include "llvm/ADT/SetVector.h"
 #include "llvm/ADT/SmallPtrSet.h"
@@ -3924,6 +3929,7 @@ TypoCorrection Sema::CorrectTypo(const DeclarationNameInfo &TypoName,
                                  Sema::LookupNameKind LookupKind,
                                  Scope *S, CXXScopeSpec *SS,
                                  CorrectionCandidateCallback &CCC,
+                                 CorrectTypoKind Mode,
                                  DeclContext *MemberContext,
                                  bool EnteringContext,
                                  const ObjCObjectPointerType *OPT,
@@ -3978,10 +3984,36 @@ TypoCorrection Sema::CorrectTypo(const DeclarationNameInfo &TypoName,
   if (getLangOpts().AltiVec && Typo->isStr("vector"))
     return TypoCorrection();
 
-  NamespaceSpecifierSet Namespaces(Context, CurContext, SS);
-
   TypoCorrectionConsumer Consumer(*this, Typo);
 
+  // Get the module loader (usually compiler instance).
+  ModuleLoader &Loader = PP.getModuleLoader();
+
+  // Look for the symbol in non-imported modules, but only if an error
+  // actually occurred.
+  if ((Mode == CTK_ErrorRecovery) && !Loader.buildingModule() &&
+      getLangOpts().Modules && getLangOpts().ModulesSearchAll) {
+    // Load global module index, or retrieve a previously loaded one.
+    GlobalModuleIndex *GlobalIndex = Loader.loadGlobalModuleIndex(
+      TypoName.getLocStart());
+
+    // Only if we have a global index.
+    if (GlobalIndex) {
+      GlobalModuleIndex::HitSet FoundModules;
+
+      // Find the modules that reference the identifier.
+      // Note that this only finds top-level modules.
+      // We'll let diagnoseTypo find the actual declaration module.
+      if (GlobalIndex->lookupIdentifier(Typo->getName(), FoundModules)) {
+        TypoCorrection TC(TypoName.getName(), (NestedNameSpecifier *)0, 0);
+        TC.setCorrectionRange(SS, TypoName);
+        TC.setRequiresImport(true);
+      }
+    }
+  }
+
+  NamespaceSpecifierSet Namespaces(Context, CurContext, SS);
+
   // If a callback object considers an empty typo correction candidate to be
   // viable, assume it does not do any actual validation of the candidates.
   TypoCorrection EmptyCorrection;

diff --git a/clang/lib/Sema/SemaOpenMP.cpp b/clang/lib/Sema/SemaOpenMP.cpp
@@ -429,7 +429,7 @@ ExprResult Sema::ActOnOpenMPIdExpression(Scope *CurScope,
   if (!Lookup.isSingleResult()) {
     VarDeclFilterCCC Validator(*this);
     if (TypoCorrection Corrected = CorrectTypo(Id, LookupOrdinaryName, CurScope,
-                                               0, Validator)) {
+                                               0, Validator, CTK_ErrorRecovery)) {
       diagnoseTypo(Corrected,
                    PDiag(Lookup.empty()? diag::err_undeclared_var_use_suggest
                                        : diag::err_omp_expected_var_arg_suggest)

diff --git a/clang/lib/Sema/SemaTemplate.cpp b/clang/lib/Sema/SemaTemplate.cpp
@@ -325,7 +325,8 @@ void Sema::LookupTemplateName(LookupResult &Found,
     FilterCCC.WantCXXNamedCasts = true;
     if (TypoCorrection Corrected = CorrectTypo(Found.getLookupNameInfo(),
                                                Found.getLookupKind(), S, &SS,
-                                               FilterCCC, LookupCtx)) {
+                                               FilterCCC, CTK_ErrorRecovery,
+                                               LookupCtx)) {
       Found.setLookupName(Corrected.getCorrection());
       if (Corrected.getCorrectionDecl())
         Found.addDecl(Corrected.getCorrectionDecl());

diff --git a/clang/lib/Sema/SemaTemplateVariadic.cpp b/clang/lib/Sema/SemaTemplateVariadic.cpp
@@ -810,7 +810,7 @@ ExprResult Sema::ActOnSizeofParameterPackExpr(Scope *S,
   case LookupResult::NotFoundInCurrentInstantiation:
     if (TypoCorrection Corrected = CorrectTypo(R.getLookupNameInfo(),
                                                R.getLookupKind(), S, 0,
-                                               Validator)) {
+                                               Validator, CTK_ErrorRecovery)) {
       diagnoseTypo(Corrected,
                    PDiag(diag::err_sizeof_pack_no_pack_name_suggest) << &Name,
                    PDiag(diag::note_parameter_pack_here));

diff --git a/clang/test/Modules/Inputs/undefined-type-fixit/module.map b/clang/test/Modules/Inputs/undefined-type-fixit/module.map
@@ -0,0 +1,9 @@
+module public1 {
+  header "public1.h"
+}
+module public2 {
+  header "public2.h"
+  module public2sub {
+    header "public2sub.h"
+  }
+}
diff --git a/clang/test/Modules/Inputs/undefined-type-fixit/public1.h b/clang/test/Modules/Inputs/undefined-type-fixit/public1.h
@@ -0,0 +1,6 @@
+#ifndef PUBLIC1_H
+#define PUBLIC1_H
+
+struct use_this1 { int field; };
+
+#endif
diff --git a/clang/test/Modules/Inputs/undefined-type-fixit/public2.h b/clang/test/Modules/Inputs/undefined-type-fixit/public2.h
@@ -0,0 +1,6 @@
+#ifndef PUBLIC2_H
+#define PUBLIC2_H
+
+struct use_this2 { int field; };
+
+#endif
diff --git a/clang/test/Modules/Inputs/undefined-type-fixit/public2sub.h b/clang/test/Modules/Inputs/undefined-type-fixit/public2sub.h
@@ -0,0 +1,6 @@
+#ifndef PUBLIC2SUB_H
+#define PUBLIC2SUB_H
+
+struct use_this2sub { int field; };
+
+#endif
diff --git a/clang/test/Modules/undefined-type-fixit1.cpp b/clang/test/Modules/undefined-type-fixit1.cpp
@@ -0,0 +1,12 @@
+// RUN: rm -rf %t
+// RUN: %clang_cc1 -fmodules-cache-path=%t -fmodules -fmodules-search-all -I %S/Inputs/undefined-type-fixit %s -verify
+
+//#include "public1.h"
+#include "public2.h"
+#include "public2sub.h"
+
+use_this1 client_variable1; // expected-error{{declaration of 'use_this1' must be imported from module 'public1' before it is required}}
+use_this2 client_variable2;
+use_this2sub client_variable2sub;
+
+// expected-note@Inputs/undefined-type-fixit/public1.h:4 {{previous declaration is here}}
diff --git a/clang/unittests/Basic/SourceManagerTest.cpp b/clang/unittests/Basic/SourceManagerTest.cpp
@@ -63,6 +63,9 @@ class VoidModuleLoader : public ModuleLoader {
                                  Module::NameVisibilityKind Visibility,
                                  SourceLocation ImportLoc,
                                  bool Complain) { }
+
+  virtual GlobalModuleIndex *loadGlobalModuleIndex(SourceLocation TriggerLoc)
+    { return 0; }
 };
 
 TEST_F(SourceManagerTest, isBeforeInTranslationUnit) {

diff --git a/clang/unittests/Lex/CMakeLists.txt b/clang/unittests/Lex/CMakeLists.txt
@@ -14,4 +14,5 @@ target_link_libraries(LexTests
   clangLex
   clangParse
   clangSema
+  clangSerialization
   )
diff --git a/clang/unittests/Lex/LexerTest.cpp b/clang/unittests/Lex/LexerTest.cpp
@@ -40,6 +40,9 @@ class VoidModuleLoader : public ModuleLoader {
                                  Module::NameVisibilityKind Visibility,
                                  SourceLocation ImportLoc,
                                  bool Complain) { }
+
+  virtual GlobalModuleIndex *loadGlobalModuleIndex(SourceLocation TriggerLoc)
+    { return 0; }
 };
 
 // The test fixture.

diff --git a/clang/unittests/Lex/Makefile b/clang/unittests/Lex/Makefile
@@ -9,8 +9,8 @@
 
 CLANG_LEVEL = ../..
 TESTNAME = Lex
-LINK_COMPONENTS := mcparser support mc
+LINK_COMPONENTS := mcparser support mc bitreader
 USEDLIBS = clangParse.a clangSema.a clangAnalysis.a clangEdit.a \
-	clangAST.a clangLex.a clangBasic.a 
+	clangSerialization.a clangAST.a clangLex.a clangBasic.a 
 
 include $(CLANG_LEVEL)/unittests/Makefile
diff --git a/clang/unittests/Lex/PPCallbacksTest.cpp b/clang/unittests/Lex/PPCallbacksTest.cpp
@@ -45,6 +45,9 @@ class VoidModuleLoader : public ModuleLoader {
                                  Module::NameVisibilityKind Visibility,
                                  SourceLocation ImportLoc,
                                  bool Complain) { }
+
+  virtual GlobalModuleIndex *loadGlobalModuleIndex(SourceLocation TriggerLoc)
+    { return 0; }
 };
 
 // Stub to collect data from InclusionDirective callbacks.

diff --git a/clang/unittests/Lex/PPConditionalDirectiveRecordTest.cpp b/clang/unittests/Lex/PPConditionalDirectiveRecordTest.cpp
@@ -64,6 +64,9 @@ class VoidModuleLoader : public ModuleLoader {
                                  Module::NameVisibilityKind Visibility,
                                  SourceLocation ImportLoc,
                                  bool Complain) { }
+
+  virtual GlobalModuleIndex *loadGlobalModuleIndex(SourceLocation TriggerLoc)
+    { return 0; }
 };
 
 TEST_F(PPConditionalDirectiveRecordTest, PPRecAPI) {