diff --git a/lib/Sema/Sema.h b/lib/Sema/Sema.h
index fab6bcf..d17e2f1 100644
--- a/lib/Sema/Sema.h
+++ b/lib/Sema/Sema.h
@@ -3336,14 +3336,16 @@
   //===--------------------------------------------------------------------===//
   // Extra semantic analysis beyond the C type system
 private:
-  Action::OwningExprResult CheckFunctionCall(FunctionDecl *FDecl,
-                                             CallExpr *TheCall);
+  bool CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall);
+  bool CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall);
   
-  Action::OwningExprResult CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall);
   SourceLocation getLocationOfStringLiteralByte(const StringLiteral *SL,
                                                 unsigned ByteNo) const;
   bool CheckablePrintfAttr(const FormatAttr *Format, CallExpr *TheCall);
   bool CheckObjCString(Expr *Arg);
+
+  Action::OwningExprResult CheckBuiltinFunctionCall(unsigned BuiltinID,
+                                                    CallExpr *TheCall);
   bool SemaBuiltinVAStart(CallExpr *TheCall);
   bool SemaBuiltinUnorderedCompare(CallExpr *TheCall);
   bool SemaBuiltinStackAddress(CallExpr *TheCall);
diff --git a/lib/Sema/SemaChecking.cpp b/lib/Sema/SemaChecking.cpp
index ffe4abd..612c4dc 100644
--- a/lib/Sema/SemaChecking.cpp
+++ b/lib/Sema/SemaChecking.cpp
@@ -100,31 +100,22 @@
   return false;
 }
 
-/// CheckFunctionCall - Check a direct function call for various correctness
-/// and safety properties not strictly enforced by the C type system.
 Action::OwningExprResult
-Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
+Sema::CheckBuiltinFunctionCall(unsigned BuiltinID, CallExpr *TheCall) {
   OwningExprResult TheCallResult(Owned(TheCall));
-  // Get the IdentifierInfo* for the called function.
-  IdentifierInfo *FnInfo = FDecl->getIdentifier();
 
-  // None of the checks below are needed for functions that don't have
-  // simple names (e.g., C++ conversion functions).
-  if (!FnInfo)
-    return move(TheCallResult);
-
-  switch (FDecl->getBuiltinID(Context)) {
+  switch (BuiltinID) {
   case Builtin::BI__builtin___CFStringMakeConstantString:
     assert(TheCall->getNumArgs() == 1 &&
            "Wrong # arguments to builtin CFStringMakeConstantString");
     if (CheckObjCString(TheCall->getArg(0)))
       return ExprError();
-    return move(TheCallResult);
+    break;
   case Builtin::BI__builtin_stdarg_start:
   case Builtin::BI__builtin_va_start:
     if (SemaBuiltinVAStart(TheCall))
       return ExprError();
-    return move(TheCallResult);
+    break;
   case Builtin::BI__builtin_isgreater:
   case Builtin::BI__builtin_isgreaterequal:
   case Builtin::BI__builtin_isless:
@@ -133,12 +124,12 @@
   case Builtin::BI__builtin_isunordered:
     if (SemaBuiltinUnorderedCompare(TheCall))
       return ExprError();
-    return move(TheCallResult);
+    break;
   case Builtin::BI__builtin_return_address:
   case Builtin::BI__builtin_frame_address:
     if (SemaBuiltinStackAddress(TheCall))
       return ExprError();
-    return move(TheCallResult);
+    break;
   case Builtin::BI__builtin_shufflevector:
     return SemaBuiltinShuffleVector(TheCall);
     // TheCall will be freed by the smart pointer here, but that's fine, since
@@ -146,15 +137,15 @@
   case Builtin::BI__builtin_prefetch:
     if (SemaBuiltinPrefetch(TheCall))
       return ExprError();
-    return move(TheCallResult);
+    break;
   case Builtin::BI__builtin_object_size:
     if (SemaBuiltinObjectSize(TheCall))
       return ExprError();
-    return move(TheCallResult);
+    break;
   case Builtin::BI__builtin_longjmp:
     if (SemaBuiltinLongjmp(TheCall))
       return ExprError();
-    return move(TheCallResult);
+    break;
   case Builtin::BI__sync_fetch_and_add:
   case Builtin::BI__sync_fetch_and_sub:
   case Builtin::BI__sync_fetch_and_or:
@@ -173,9 +164,23 @@
   case Builtin::BI__sync_lock_release:
     if (SemaBuiltinAtomicOverloaded(TheCall))
       return ExprError();
-    return move(TheCallResult);
+    break;
   }
+  
+  return move(TheCallResult);
+}
 
+/// CheckFunctionCall - Check a direct function call for various correctness
+/// and safety properties not strictly enforced by the C type system.
+bool Sema::CheckFunctionCall(FunctionDecl *FDecl, CallExpr *TheCall) {
+  // Get the IdentifierInfo* for the called function.
+  IdentifierInfo *FnInfo = FDecl->getIdentifier();
+
+  // None of the checks below are needed for functions that don't have
+  // simple names (e.g., C++ conversion functions).
+  if (!FnInfo)
+    return false;
+  
   // FIXME: This mechanism should be abstracted to be less fragile and
   // more efficient. For example, just map function ids to custom
   // handlers.
@@ -193,41 +198,42 @@
                            HasVAListArg ? 0 : Format->getFirstArg() - 1);
     }
   }
-  for (const Attr *attr = FDecl->getAttrs(); 
-       attr; attr = attr->getNext()) {
-    if (const NonNullAttr *NonNull = dyn_cast<NonNullAttr>(attr))
-      CheckNonNullArguments(NonNull, TheCall);
-  }
+  
+  for (const NonNullAttr *NonNull = FDecl->getAttr<NonNullAttr>(); NonNull; 
+       NonNull = NonNull->getNext<NonNullAttr>())
+    CheckNonNullArguments(NonNull, TheCall);
 
-  return move(TheCallResult);
+  return false;
 }
 
-Action::OwningExprResult
-Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
-
-  OwningExprResult TheCallResult(Owned(TheCall));
+bool Sema::CheckBlockCall(NamedDecl *NDecl, CallExpr *TheCall) {
   // Printf checking.
   const FormatAttr *Format = NDecl->getAttr<FormatAttr>();
   if (!Format)
-    return move(TheCallResult);
+    return false;
+  
   const VarDecl *V = dyn_cast<VarDecl>(NDecl);
   if (!V)
-    return move(TheCallResult);
+    return false;
+  
   QualType Ty = V->getType();
   if (!Ty->isBlockPointerType())
-    return move(TheCallResult);
-  if (CheckablePrintfAttr(Format, TheCall)) {
-      bool HasVAListArg = Format->getFirstArg() == 0;
-      if (!HasVAListArg) {
-        const FunctionType *FT = 
-          Ty->getAs<BlockPointerType>()->getPointeeType()->getAsFunctionType();
-        if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT))
-          HasVAListArg = !Proto->isVariadic();
-      }
-      CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1,
-                           HasVAListArg ? 0 : Format->getFirstArg() - 1);
+    return false;
+  
+  if (!CheckablePrintfAttr(Format, TheCall))
+    return false;
+  
+  bool HasVAListArg = Format->getFirstArg() == 0;
+  if (!HasVAListArg) {
+    const FunctionType *FT = 
+      Ty->getAs<BlockPointerType>()->getPointeeType()->getAsFunctionType();
+    if (const FunctionProtoType *Proto = dyn_cast<FunctionProtoType>(FT))
+      HasVAListArg = !Proto->isVariadic();
   }
-  return move(TheCallResult);
+  CheckPrintfArguments(TheCall, HasVAListArg, Format->getFormatIdx() - 1,
+                       HasVAListArg ? 0 : Format->getFirstArg() - 1);
+
+  return false;
 }
 
 /// SemaBuiltinAtomicOverloaded - We have a call to a function like
diff --git a/lib/Sema/SemaExpr.cpp b/lib/Sema/SemaExpr.cpp
index 1a519ff..5f1467c 100644
--- a/lib/Sema/SemaExpr.cpp
+++ b/lib/Sema/SemaExpr.cpp
@@ -2929,11 +2929,18 @@
   // Check for sentinels
   if (NDecl)
     DiagnoseSentinelCalls(NDecl, LParenLoc, Args, NumArgs);
+  
   // Do special checking on direct calls to functions.
-  if (FDecl)
-    return CheckFunctionCall(FDecl, TheCall.take());
-  if (NDecl)
-    return CheckBlockCall(NDecl, TheCall.take());
+  if (FDecl) {
+    if (CheckFunctionCall(FDecl, TheCall.get()))
+      return ExprError();
+    
+    if (unsigned BuiltinID = FDecl->getBuiltinID(Context)) 
+      return CheckBuiltinFunctionCall(BuiltinID, TheCall.take());
+  } else if (NDecl) {
+    if (CheckBlockCall(NDecl, TheCall.get()))
+      return ExprError();
+  }
 
   return Owned(TheCall.take());
 }
diff --git a/lib/Sema/SemaOverload.cpp b/lib/Sema/SemaOverload.cpp
index faf4d82..d45e54a 100644
--- a/lib/Sema/SemaOverload.cpp
+++ b/lib/Sema/SemaOverload.cpp
@@ -4343,7 +4343,10 @@
                               RParenLoc))
     return true;
 
-  return CheckFunctionCall(Method, TheCall.take()).release();
+  if (CheckFunctionCall(Method, TheCall.get()))
+    return true;
+  
+  return TheCall.release();
 }
 
 /// BuildCallToObjectOfClassType - Build a call to an object of class
@@ -4549,7 +4552,10 @@
 
   if (IsError) return true;
 
-  return CheckFunctionCall(Method, TheCall.take()).release();
+  if (CheckFunctionCall(Method, TheCall.get()))
+    return true;
+
+  return TheCall.release();
 }
 
 /// BuildOverloadedArrowExpr - Build a call to an overloaded @c operator->