diff --git a/llvm/lib/Target/TargetTransformImpl.cpp b/llvm/lib/Target/TargetTransformImpl.cpp
index c07332d..b36e6f8 100644
--- a/llvm/lib/Target/TargetTransformImpl.cpp
+++ b/llvm/lib/Target/TargetTransformImpl.cpp
@@ -214,8 +214,16 @@
   // Handle scalar conversions.
   if (!Src->isVectorTy() && !Dst->isVectorTy()) {
 
-    // Scalar bitcasts and truncs are usually free.
-    if (Opcode == Instruction::BitCast || Opcode == Instruction::Trunc)
+    // Scalar bitcasts are usually free.
+    if (Opcode == Instruction::BitCast)
+      return 0;
+
+    if (Opcode == Instruction::Trunc &&
+        TLI->isTruncateFree(SrcLT.second, DstLT.second))
+      return 0;
+
+    if (Opcode == Instruction::ZExt &&
+        TLI->isZExtFree(SrcLT.second, DstLT.second))
       return 0;
 
     // Just check the op cost. If the operation is legal then assume it costs 1.