Index: llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
===================================================================
--- llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
+++ llvm/include/llvm/Analysis/TargetTransformInfoImpl.h
@@ -854,9 +854,9 @@
     case Instruction::FPExt:
     case Instruction::SExt:
     case Instruction::ZExt:
-      if (TargetTTI->getExtCost(I, Operands.back()) == TTI::TCC_Free)
-        return TTI::TCC_Free;
-      break;
+      if (I && TargetTTI->getExtCost(I, Operands.back()) == 0)
+        return 0;
+      return TargetTTI->getCastInstrCost(Opcode, Ty, OpTy, I);
     }
     // By default, just classify everything as 'basic'.
     return TTI::TCC_Basic;
Index: llvm/test/Analysis/CostModel/SystemZ/ext-of-icmp-cost.ll
===================================================================
--- llvm/test/Analysis/CostModel/SystemZ/ext-of-icmp-cost.ll
+++ llvm/test/Analysis/CostModel/SystemZ/ext-of-icmp-cost.ll
@@ -7,7 +7,7 @@
 define i64 @fun1(i64 %v) {
 ; CHECK-LABEL: 'fun1'
 ; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %cmp = icmp eq i64 %v, 0
-; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %z = zext i1 %cmp to i64
+; CHECK: Cost Model: Found an estimated cost of 2 for instruction:   %z = zext i1 %cmp to i64
 ; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   ret i64 %z
   %cmp = icmp eq i64 %v, 0
   %z = zext i1 %cmp to i64
@@ -17,7 +17,7 @@
 define i64 @fun2(i64 %v) {
 ; CHECK-LABEL: 'fun2'
 ; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %cmp = icmp eq i64 %v, 0
-; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %z = sext i1 %cmp to i64
+; CHECK: Cost Model: Found an estimated cost of 2 for instruction:   %z = sext i1 %cmp to i64
 ; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   ret i64 %z
   %cmp = icmp eq i64 %v, 0
   %z = sext i1 %cmp to i64
@@ -46,7 +46,7 @@
 
 define i64 @fun5(i1 %v) {
 ; CHECK-LABEL: 'fun5'
-; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   %z = zext i1 %v to i64
+; CHECK: Cost Model: Found an estimated cost of 2 for instruction:   %z = zext i1 %v to i64
 ; CHECK: Cost Model: Found an estimated cost of 1 for instruction:   ret i64 %z
   %z = zext i1 %v to i64
   ret i64 %z