diff --git a/clang/include/clang/Driver/HostInfo.h b/clang/include/clang/Driver/HostInfo.h
index 1b99a4459d16..af6ef822fbfd 100644
--- a/clang/include/clang/Driver/HostInfo.h
+++ b/clang/include/clang/Driver/HostInfo.h
@@ -10,7 +10,6 @@
 #ifndef CLANG_DRIVER_HOSTINFO_H_
 #define CLANG_DRIVER_HOSTINFO_H_
 
-#include "clang/Driver/Types.h"
 #include "llvm/ADT/Triple.h"
 #include <string>
 
@@ -48,10 +47,6 @@ public:
   /// this host and support -arch, -Xarch, etc.
   virtual bool useDriverDriver() const = 0;
 
-  /// lookupTypeForExtension - Return the default language type to use for the
-  /// given extension.
-  virtual types::ID lookupTypeForExtension(const char *Ext) const = 0;
-
   /// CreateToolChain - Construct the toolchain to use for this host (which the
   /// host retains ownership of).
   ///
diff --git a/clang/include/clang/Driver/ToolChain.h b/clang/include/clang/Driver/ToolChain.h
index 11a153c48ca3..ee18315832cf 100644
--- a/clang/include/clang/Driver/ToolChain.h
+++ b/clang/include/clang/Driver/ToolChain.h
@@ -10,6 +10,7 @@
 #ifndef CLANG_DRIVER_TOOLCHAIN_H_
 #define CLANG_DRIVER_TOOLCHAIN_H_
 
+#include "clang/Driver/Types.h"
 #include "llvm/ADT/SmallVector.h"
 #include "llvm/ADT/Triple.h"
 #include "llvm/System/Path.h"
@@ -89,6 +90,10 @@ public:
 
   // Platform defaults information
 
+  /// LookupTypeForExtension - Return the default language type to use for the
+  /// given extension.
+  virtual types::ID LookupTypeForExtension(const char *Ext) const;
+
   /// IsBlocksDefault - Does this tool chain enable -fblocks by default.
   virtual bool IsBlocksDefault() const { return false; }
 
diff --git a/clang/lib/Driver/Driver.cpp b/clang/lib/Driver/Driver.cpp
index e28b2bc6ed84..7fbbe0b838ce 100644
--- a/clang/lib/Driver/Driver.cpp
+++ b/clang/lib/Driver/Driver.cpp
@@ -662,7 +662,7 @@ void Driver::BuildActions(const ToolChain &TC, const ArgList &Args,
           // found. We use a host hook here because Darwin at least has its own
           // idea of what .s is.
           if (const char *Ext = strrchr(Value, '.'))
-            Ty = Host->lookupTypeForExtension(Ext + 1);
+            Ty = TC.LookupTypeForExtension(Ext + 1);
 
           if (Ty == types::TY_INVALID)
             Ty = types::TY_Object;
diff --git a/clang/lib/Driver/HostInfo.cpp b/clang/lib/Driver/HostInfo.cpp
index 0636d9eab15c..a8fdec8a103e 100644
--- a/clang/lib/Driver/HostInfo.cpp
+++ b/clang/lib/Driver/HostInfo.cpp
@@ -53,17 +53,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    types::ID Ty = types::lookupTypeForExtension(Ext);
-
-    // Darwin always preprocesses assembly files (unless -x is used
-    // explicitly).
-    if (Ty == types::TY_PP_Asm)
-      return types::TY_Asm;
-
-    return Ty;
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
@@ -170,15 +159,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    types::ID Ty = types::lookupTypeForExtension(Ext);
-
-    if (Ty == types::TY_PP_Asm)
-      return types::TY_Asm;
-
-    return Ty;
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args, 
                                      const char *ArchName) const;
 };
@@ -212,10 +192,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    return types::lookupTypeForExtension(Ext);
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
@@ -279,10 +255,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    return types::lookupTypeForExtension(Ext);
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
@@ -330,10 +302,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    return types::lookupTypeForExtension(Ext);
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
@@ -379,10 +347,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    return types::lookupTypeForExtension(Ext);
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
@@ -439,10 +403,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    return types::lookupTypeForExtension(Ext);
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
@@ -491,10 +451,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    return types::lookupTypeForExtension(Ext);
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
@@ -540,10 +496,6 @@ public:
 
   virtual bool useDriverDriver() const;
 
-  virtual types::ID lookupTypeForExtension(const char *Ext) const {
-    return types::lookupTypeForExtension(Ext);
-  }
-
   virtual ToolChain *CreateToolChain(const ArgList &Args,
                                      const char *ArchName) const;
 };
diff --git a/clang/lib/Driver/ToolChain.cpp b/clang/lib/Driver/ToolChain.cpp
index 9fae67de32f4..ab907c1aeff6 100644
--- a/clang/lib/Driver/ToolChain.cpp
+++ b/clang/lib/Driver/ToolChain.cpp
@@ -34,3 +34,7 @@ std::string ToolChain::GetFilePath(const char *Name) const {
 std::string ToolChain::GetProgramPath(const char *Name, bool WantFile) const {
   return Host.getDriver().GetProgramPath(Name, *this, WantFile);
 }
+
+types::ID ToolChain::LookupTypeForExtension(const char *Ext) const {
+  return types::lookupTypeForExtension(Ext);
+}
diff --git a/clang/lib/Driver/ToolChains.cpp b/clang/lib/Driver/ToolChains.cpp
index 0449711208eb..bdccc3e3da29 100644
--- a/clang/lib/Driver/ToolChains.cpp
+++ b/clang/lib/Driver/ToolChains.cpp
@@ -40,6 +40,16 @@ Darwin::Darwin(const HostInfo &Host, const llvm::Triple& Triple,
     << _DarwinVersion[1];
 }
 
+types::ID Darwin::LookupTypeForExtension(const char *Ext) const {
+  types::ID Ty = types::lookupTypeForExtension(Ext);
+
+  // Darwin always preprocesses assembly files (unless -x is used explicitly).
+  if (Ty == types::TY_PP_Asm)
+    return types::TY_Asm;
+
+  return Ty;
+}
+
 // FIXME: Can we tablegen this?
 static const char *GetArmArchForMArch(llvm::StringRef Value) {
   if (Value == "armv6k")
diff --git a/clang/lib/Driver/ToolChains.h b/clang/lib/Driver/ToolChains.h
index b6c7badf3b3f..06d4fff4e7cc 100644
--- a/clang/lib/Driver/ToolChains.h
+++ b/clang/lib/Driver/ToolChains.h
@@ -147,6 +147,8 @@ public:
   /// @name ToolChain Implementation
   /// {
 
+  virtual types::ID LookupTypeForExtension(const char *Ext) const;
+
   virtual DerivedArgList *TranslateArgs(const DerivedArgList &Args,
                                         const char *BoundArch) const;