Index: lib/Target/X86/X86ISelLowering.cpp
===================================================================
--- lib/Target/X86/X86ISelLowering.cpp
+++ lib/Target/X86/X86ISelLowering.cpp
@@ -39877,18 +39877,24 @@
 
 // Try to combine sext_in_reg of a cmov of constants by extending the constants.
 static SDValue combineSextInRegCmov(SDNode *N, SelectionDAG &DAG) {
+  assert(N->getOpcode() == ISD::SIGN_EXTEND_INREG);
+
   EVT VT = N->getValueType(0);
 
   SDValue N0 = N->getOperand(0);
   SDValue N1 = N->getOperand(1);
   EVT ExtraVT = cast<VTSDNode>(N1)->getVT();
 
-  if (ExtraVT != MVT::i16)
+  if (ExtraVT != MVT::i8 && ExtraVT != MVT::i16)
     return SDValue();
 
-  // Look through single use any_extends.
-  if (N0.getOpcode() == ISD::ANY_EXTEND && N0.hasOneUse())
+  // Look through single use any_extends / truncs.
+  SDValue IntemediateBitwidthOp;
+  if ((N0.getOpcode() == ISD::ANY_EXTEND || N0.getOpcode() == ISD::TRUNCATE) &&
+      N0.hasOneUse()) {
+    IntemediateBitwidthOp = N0;
     N0 = N0.getOperand(0);
+  }
 
   // See if we have a single use cmov.
   if (N0.getOpcode() != X86ISD::CMOV || !N0.hasOneUse())
@@ -39904,10 +39910,10 @@
 
   SDLoc DL(N);
 
-  // If we looked through an any_extend above, add one to the constants.
-  if (N0.getValueType() != VT) {
-    CMovOp0 = DAG.getNode(ISD::ANY_EXTEND, DL, VT, CMovOp0);
-    CMovOp1 = DAG.getNode(ISD::ANY_EXTEND, DL, VT, CMovOp1);
+  // If we looked through an any_extend/trunc above, add one to the constants.
+  if (IntemediateBitwidthOp) {
+    CMovOp0 = DAG.getNode(IntemediateBitwidthOp.getOpcode(), DL, VT, CMovOp0);
+    CMovOp1 = DAG.getNode(IntemediateBitwidthOp.getOpcode(), DL, VT, CMovOp1);
   }
 
   CMovOp0 = DAG.getNode(ISD::SIGN_EXTEND_INREG, DL, VT, CMovOp0, N1);
@@ -39919,6 +39925,8 @@
 
 static SDValue combineSignExtendInReg(SDNode *N, SelectionDAG &DAG,
                                       const X86Subtarget &Subtarget) {
+  assert(N->getOpcode() == ISD::SIGN_EXTEND_INREG);
+
   if (SDValue V = combineSextInRegCmov(N, DAG))
     return V;
 
Index: test/CodeGen/X86/cmov-promotion.ll
===================================================================
--- test/CodeGen/X86/cmov-promotion.ll
+++ test/CodeGen/X86/cmov-promotion.ll
@@ -152,11 +152,9 @@
 ; CMOV-LABEL: cmov_spromotion_8_to_16:
 ; CMOV:       # %bb.0:
 ; CMOV-NEXT:    testb $1, %dil
-; CMOV-NEXT:    movl $117, %eax
-; CMOV-NEXT:    movl $237, %ecx
-; CMOV-NEXT:    cmovnel %eax, %ecx
-; CMOV-NEXT:    movsbl %cl, %eax
-; CMOV-NEXT:    # kill: def $ax killed $ax killed $eax
+; CMOV-NEXT:    movw $117, %cx
+; CMOV-NEXT:    movw $-19, %ax
+; CMOV-NEXT:    cmovnew %cx, %ax
 ; CMOV-NEXT:    retq
 ;
 ; NO_CMOV-LABEL: cmov_spromotion_8_to_16:
@@ -179,10 +177,9 @@
 ; CMOV-LABEL: cmov_spromotion_8_to_32:
 ; CMOV:       # %bb.0:
 ; CMOV-NEXT:    testb $1, %dil
-; CMOV-NEXT:    movl $126, %eax
-; CMOV-NEXT:    movl $255, %ecx
-; CMOV-NEXT:    cmovnel %eax, %ecx
-; CMOV-NEXT:    movsbl %cl, %eax
+; CMOV-NEXT:    movl $126, %ecx
+; CMOV-NEXT:    movl $-1, %eax
+; CMOV-NEXT:    cmovnel %ecx, %eax
 ; CMOV-NEXT:    retq
 ;
 ; NO_CMOV-LABEL: cmov_spromotion_8_to_32:
@@ -204,10 +201,9 @@
 ; CMOV-LABEL: cmov_spromotion_8_to_64:
 ; CMOV:       # %bb.0:
 ; CMOV-NEXT:    testb $1, %dil
-; CMOV-NEXT:    movl $126, %eax
-; CMOV-NEXT:    movl $255, %ecx
-; CMOV-NEXT:    cmovnel %eax, %ecx
-; CMOV-NEXT:    movsbq %cl, %rax
+; CMOV-NEXT:    movl $126, %ecx
+; CMOV-NEXT:    movq $-1, %rax
+; CMOV-NEXT:    cmovneq %rcx, %rax
 ; CMOV-NEXT:    retq
 ;
 ; NO_CMOV-LABEL: cmov_spromotion_8_to_64: