diff --git a/include/clang/Basic/Module.h b/include/clang/Basic/Module.h
index e75f43e..82dbd5b 100644
--- a/include/clang/Basic/Module.h
+++ b/include/clang/Basic/Module.h
@@ -33,6 +33,7 @@
 class DirectoryEntry;
 class FileEntry;
 class LangOptions;
+class TargetInfo;
   
 /// \brief Describes the name of a module.
 typedef llvm::SmallVector<std::pair<std::string, SourceLocation>, 2>
@@ -178,10 +179,14 @@
   /// \param LangOpts The language options used for the current
   /// translation unit.
   ///
+  /// \param Target The target options used for the current translation unit.
+  ///
   /// \param Feature If this module is unavailable, this parameter
   /// will be set to one of the features that is required for use of
   /// this module (but is not available).
-  bool isAvailable(const LangOptions &LangOpts, StringRef &Feature) const;
+  bool isAvailable(const LangOptions &LangOpts, 
+                   const TargetInfo &Target,
+                   StringRef &Feature) const;
 
   /// \brief Determine whether this module is a submodule.
   bool isSubModule() const { return Parent != 0; }
@@ -246,7 +251,11 @@
   ///
   /// \param LangOpts The set of language options that will be used to
   /// evaluate the availability of this feature.
-  void addRequirement(StringRef Feature, const LangOptions &LangOpts);
+  ///
+  /// \param Target The target options that will be used to evaluate the
+  /// availability of this feature.
+  void addRequirement(StringRef Feature, const LangOptions &LangOpts,
+                      const TargetInfo &Target);
 
   /// \brief Find the submodule with the given name.
   ///
diff --git a/include/clang/Lex/HeaderSearch.h b/include/clang/Lex/HeaderSearch.h
index c596948..84bb37d 100644
--- a/include/clang/Lex/HeaderSearch.h
+++ b/include/clang/Lex/HeaderSearch.h
@@ -189,7 +189,7 @@
   
 public:
   HeaderSearch(FileManager &FM, DiagnosticsEngine &Diags,
-               const LangOptions &LangOpts);
+               const LangOptions &LangOpts, const TargetInfo *Target);
   ~HeaderSearch();
 
   FileManager &getFileMgr() const { return FileMgr; }
@@ -243,6 +243,10 @@
     ExternalSource = ES;
   }
   
+  /// \brief Set the target information for the header search, if not
+  /// already known.
+  void setTarget(const TargetInfo &Target);
+  
   /// LookupFile - Given a "foo" or <foo> reference, look up the indicated file,
   /// return null on failure.
   ///
diff --git a/include/clang/Lex/ModuleMap.h b/include/clang/Lex/ModuleMap.h
index 3e794f5..6176ed8 100644
--- a/include/clang/Lex/ModuleMap.h
+++ b/include/clang/Lex/ModuleMap.h
@@ -39,7 +39,8 @@
   SourceManager *SourceMgr;
   llvm::IntrusiveRefCntPtr<DiagnosticsEngine> Diags;
   const LangOptions &LangOpts;
-
+  const TargetInfo *Target;
+  
   /// \brief Language options used to parse the module map itself.
   ///
   /// These are always simple C language options.
@@ -89,13 +90,18 @@
   /// diagnostics.
   ///
   /// \param LangOpts Language options for this translation unit.
+  ///
+  /// \param Target The target for this translation unit.
   ModuleMap(FileManager &FileMgr, const DiagnosticConsumer &DC,
-            const LangOptions &LangOpts);
+            const LangOptions &LangOpts, const TargetInfo *Target);
 
   /// \brief Destroy the module map.
   ///
   ~ModuleMap();
-  
+
+  /// \brief Set the target information.
+  void setTarget(const TargetInfo &Target);
+
   /// \brief Retrieve the module that owns the given header file, if any.
   ///
   /// \param File The header file that is likely to be included.
diff --git a/lib/Basic/Module.cpp b/lib/Basic/Module.cpp
index 015f421..3052532 100644
--- a/lib/Basic/Module.cpp
+++ b/lib/Basic/Module.cpp
@@ -47,7 +47,8 @@
 
 /// \brief Determine whether a translation unit built using the current
 /// language options has the given feature.
-static bool hasFeature(StringRef Feature, const LangOptions &LangOpts) {
+static bool hasFeature(StringRef Feature, const LangOptions &LangOpts,
+                       const TargetInfo &Target) {
   return llvm::StringSwitch<bool>(Feature)
            .Case("blocks", LangOpts.Blocks)
            .Case("cplusplus", LangOpts.CPlusPlus)
@@ -58,13 +59,14 @@
 }
 
 bool 
-Module::isAvailable(const LangOptions &LangOpts, StringRef &Feature) const {
+Module::isAvailable(const LangOptions &LangOpts, const TargetInfo &Target,
+                    StringRef &Feature) const {
   if (IsAvailable)
     return true;
 
   for (const Module *Current = this; Current; Current = Current->Parent) {
     for (unsigned I = 0, N = Current->Requires.size(); I != N; ++I) {
-      if (!hasFeature(Current->Requires[I], LangOpts)) {
+      if (!hasFeature(Current->Requires[I], LangOpts, Target)) {
         Feature = Current->Requires[I];
         return false;
       }
@@ -121,11 +123,12 @@
   return Umbrella.dyn_cast<const DirectoryEntry *>();
 }
 
-void Module::addRequirement(StringRef Feature, const LangOptions &LangOpts) {
+void Module::addRequirement(StringRef Feature, const LangOptions &LangOpts,
+                            const TargetInfo &Target) {
   Requires.push_back(Feature);
 
   // If this feature is currently available, we're done.
-  if (hasFeature(Feature, LangOpts))
+  if (hasFeature(Feature, LangOpts, Target))
     return;
 
   if (!IsAvailable)
diff --git a/lib/Frontend/ASTUnit.cpp b/lib/Frontend/ASTUnit.cpp
index abeb317..ff75e3a 100644
--- a/lib/Frontend/ASTUnit.cpp
+++ b/lib/Frontend/ASTUnit.cpp
@@ -673,7 +673,8 @@
                                      AST->getFileManager());
   AST->HeaderInfo.reset(new HeaderSearch(AST->getFileManager(),
                                          AST->getDiagnostics(),
-                                         AST->ASTFileLangOpts));
+                                         AST->ASTFileLangOpts,
+                                         /*Target=*/0));
   
   for (unsigned I = 0; I != NumRemappedFiles; ++I) {
     FilenameOrMemBuf fileOrBuf = RemappedFiles[I].second;
diff --git a/lib/Frontend/CompilerInstance.cpp b/lib/Frontend/CompilerInstance.cpp
index e8afe6d..1501da4 100644
--- a/lib/Frontend/CompilerInstance.cpp
+++ b/lib/Frontend/CompilerInstance.cpp
@@ -242,7 +242,8 @@
   // Create the Preprocessor.
   HeaderSearch *HeaderInfo = new HeaderSearch(getFileManager(), 
                                               getDiagnostics(),
-                                              getLangOpts());
+                                              getLangOpts(),
+                                              &getTarget());
   PP = new Preprocessor(getDiagnostics(), getLangOpts(), &getTarget(),
                         getSourceManager(), *HeaderInfo, *this, PTHMgr,
                         /*OwnsHeaderSearch=*/true);
@@ -1045,7 +1046,7 @@
 
     // Check whether this module is available.
     StringRef Feature;
-    if (!Module->isAvailable(getLangOpts(), Feature)) {
+    if (!Module->isAvailable(getLangOpts(), getTarget(), Feature)) {
       getDiagnostics().Report(ImportLoc, diag::err_module_unavailable)
         << Module->getFullModuleName()
         << Feature
diff --git a/lib/Frontend/FrontendActions.cpp b/lib/Frontend/FrontendActions.cpp
index 669fe4a..c030232 100644
--- a/lib/Frontend/FrontendActions.cpp
+++ b/lib/Frontend/FrontendActions.cpp
@@ -237,7 +237,7 @@
 
   // Check whether we can build this module at all.
   StringRef Feature;
-  if (!Module->isAvailable(CI.getLangOpts(), Feature)) {
+  if (!Module->isAvailable(CI.getLangOpts(), CI.getTarget(), Feature)) {
     CI.getDiagnostics().Report(diag::err_module_unavailable)
       << Module->getFullModuleName()
       << Feature;
diff --git a/lib/Lex/HeaderSearch.cpp b/lib/Lex/HeaderSearch.cpp
index e56eb6c..e3a6c52 100644
--- a/lib/Lex/HeaderSearch.cpp
+++ b/lib/Lex/HeaderSearch.cpp
@@ -39,9 +39,10 @@
 ExternalHeaderFileInfoSource::~ExternalHeaderFileInfoSource() {}
 
 HeaderSearch::HeaderSearch(FileManager &FM, DiagnosticsEngine &Diags,
-                           const LangOptions &LangOpts)
+                           const LangOptions &LangOpts, 
+                           const TargetInfo *Target)
   : FileMgr(FM), Diags(Diags), FrameworkMap(64), 
-    ModMap(FileMgr, *Diags.getClient(), LangOpts) 
+    ModMap(FileMgr, *Diags.getClient(), LangOpts, Target)
 {
   AngledDirIdx = 0;
   SystemDirIdx = 0;
@@ -365,6 +366,10 @@
   return FE;
 }
 
+void HeaderSearch::setTarget(const TargetInfo &Target) {
+  ModMap.setTarget(Target);
+}
+
 
 //===----------------------------------------------------------------------===//
 // Header File Location.
diff --git a/lib/Lex/ModuleMap.cpp b/lib/Lex/ModuleMap.cpp
index 708da94..3583b03 100644
--- a/lib/Lex/ModuleMap.cpp
+++ b/lib/Lex/ModuleMap.cpp
@@ -70,8 +70,8 @@
 }
 
 ModuleMap::ModuleMap(FileManager &FileMgr, const DiagnosticConsumer &DC,
-                     const LangOptions &LangOpts)
-  : LangOpts(LangOpts)
+                     const LangOptions &LangOpts, const TargetInfo *Target)
+  : LangOpts(LangOpts), Target(Target)
 {
   llvm::IntrusiveRefCntPtr<DiagnosticIDs> DiagIDs(new DiagnosticIDs);
   Diags = llvm::IntrusiveRefCntPtr<DiagnosticsEngine>(
@@ -90,6 +90,12 @@
   delete SourceMgr;
 }
 
+void ModuleMap::setTarget(const TargetInfo &Target) {
+  assert((!this->Target || this->Target == &Target) && 
+         "Improper target override");
+  this->Target = &Target;
+}
+
 Module *ModuleMap::findModuleForHeader(const FileEntry *File) {
   llvm::DenseMap<const FileEntry *, Module *>::iterator Known
     = Headers.find(File);
@@ -992,7 +998,7 @@
     consumeToken();
 
     // Add this feature.
-    ActiveModule->addRequirement(Feature, Map.LangOpts);
+    ActiveModule->addRequirement(Feature, Map.LangOpts, *Map.Target);
 
     if (!Tok.is(MMToken::Comma))
       break;
@@ -1360,6 +1366,7 @@
 }
 
 bool ModuleMap::parseModuleMapFile(const FileEntry *File) {
+  assert(Target != 0 && "Missing target information");
   FileID ID = SourceMgr->createFileID(File, SourceLocation(), SrcMgr::C_User);
   const llvm::MemoryBuffer *Buffer = SourceMgr->getBuffer(ID);
   if (!Buffer)
diff --git a/lib/Lex/Preprocessor.cpp b/lib/Lex/Preprocessor.cpp
index 05cbffd..fc6efb6 100644
--- a/lib/Lex/Preprocessor.cpp
+++ b/lib/Lex/Preprocessor.cpp
@@ -167,7 +167,9 @@
     Ident__exception_info = Ident__exception_code = Ident__abnormal_termination = 0;
     Ident___exception_info = Ident___exception_code = Ident___abnormal_termination = 0;
     Ident_GetExceptionInfo = Ident_GetExceptionCode = Ident_AbnormalTermination = 0;
-  } 
+  }
+  
+  HeaderInfo.setTarget(Target);
 }
 
 void Preprocessor::setPTHManager(PTHManager* pm) {
diff --git a/lib/Serialization/ASTReader.cpp b/lib/Serialization/ASTReader.cpp
index 7173402..0bf1da7 100644
--- a/lib/Serialization/ASTReader.cpp
+++ b/lib/Serialization/ASTReader.cpp
@@ -3307,7 +3307,8 @@
         break;
 
       CurrentModule->addRequirement(StringRef(BlobStart, BlobLen), 
-                                    Context.getLangOptions());
+                                    Context.getLangOptions(),
+                                    Context.getTargetInfo());
       break;
     }
     }
diff --git a/unittests/Basic/SourceManagerTest.cpp b/unittests/Basic/SourceManagerTest.cpp
index 2dd64f9..1b067b0 100644
--- a/unittests/Basic/SourceManagerTest.cpp
+++ b/unittests/Basic/SourceManagerTest.cpp
@@ -63,7 +63,7 @@
   FileID mainFileID = SourceMgr.createMainFileIDForMemBuffer(buf);
 
   VoidModuleLoader ModLoader;
-  HeaderSearch HeaderInfo(FileMgr, Diags, LangOpts);
+  HeaderSearch HeaderInfo(FileMgr, Diags, LangOpts, &*Target);
   Preprocessor PP(Diags, LangOpts,
                   Target.getPtr(),
                   SourceMgr, HeaderInfo, ModLoader,
@@ -130,7 +130,7 @@
   SourceMgr.overrideFileContents(headerFile, headerBuf);
 
   VoidModuleLoader ModLoader;
-  HeaderSearch HeaderInfo(FileMgr, Diags, LangOpts);
+  HeaderSearch HeaderInfo(FileMgr, Diags, LangOpts, &*Target);
   Preprocessor PP(Diags, LangOpts,
                   Target.getPtr(),
                   SourceMgr, HeaderInfo, ModLoader,
diff --git a/unittests/Lex/LexerTest.cpp b/unittests/Lex/LexerTest.cpp
index de94d1d..2742f66 100644
--- a/unittests/Lex/LexerTest.cpp
+++ b/unittests/Lex/LexerTest.cpp
@@ -69,7 +69,7 @@
   SourceMgr.createMainFileIDForMemBuffer(buf);
 
   VoidModuleLoader ModLoader;
-  HeaderSearch HeaderInfo(FileMgr, Diags, LangOpts);
+  HeaderSearch HeaderInfo(FileMgr, Diags, LangOpts, &*Target);
   Preprocessor PP(Diags, LangOpts,
                   Target.getPtr(),
                   SourceMgr, HeaderInfo, ModLoader,