diff --git a/lib/Target/X86/X86ISelLowering.cpp b/lib/Target/X86/X86ISelLowering.cpp
index c0ebade..e27d93c 100644
--- a/lib/Target/X86/X86ISelLowering.cpp
+++ b/lib/Target/X86/X86ISelLowering.cpp
@@ -2252,10 +2252,26 @@
 
   // If -tailcallopt is specified, make fastcc functions tail-callable.
   const Function *CallerF = DAG.getMachineFunction().getFunction();
-  if (PerformTailCallOpt &&
-      CalleeCC == CallingConv::Fast &&
-      CallerF->getCallingConv() == CalleeCC)
-    return true;
+  if (PerformTailCallOpt) {
+    if (CalleeCC == CallingConv::Fast &&
+        CallerF->getCallingConv() == CalleeCC)
+      return true;
+    return false;
+  }
+
+  // Do not tail call optimize vararg calls for now.
+  if (isVarArg)
+    return false;
+
+  // Don't tail call optimize recursive call.
+  GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
+  const Function *CalleeF = G ? cast<Function>(G->getGlobal()) : 0;
+  if (CallerF == CalleeF)
+    return false;
+  // If it's an indirect call, conversatively return false if the caller's
+  // address is taken.
+  if (!isa<ExternalSymbolSDNode>(Callee) && CallerF->hasAddressTaken())
+    return false;
 
   // Look for obvious safe cases to perform tail call optimization.
   // If the callee takes no arguments then go on to check the results of the
@@ -2279,9 +2295,7 @@
     return true;
 
   // If the return types match, then it's safe.
-  GlobalAddressSDNode *G = dyn_cast<GlobalAddressSDNode>(Callee);
   if (!G) return false;  // FIXME: common external symbols?
-  Function *CalleeF = cast<Function>(G->getGlobal());
   const Type *CalleeRetTy = CalleeF->getReturnType();
   return CallerRetTy == CalleeRetTy;
 }