diff --git a/llvm/lib/Target/X86/X86ISelLowering.cpp b/llvm/lib/Target/X86/X86ISelLowering.cpp
index 0d7258dd2a71..f8a390cf8f78 100644
--- a/llvm/lib/Target/X86/X86ISelLowering.cpp
+++ b/llvm/lib/Target/X86/X86ISelLowering.cpp
@@ -1525,17 +1525,17 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
     if (Subtarget->hasCDI()) {
       setOperationAction(ISD::CTLZ,             MVT::v8i64,  Legal);
       setOperationAction(ISD::CTLZ,             MVT::v16i32, Legal);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i64,  Legal);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v16i32, Legal);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i64,  Expand);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v16i32, Expand);
 
       setOperationAction(ISD::CTLZ,             MVT::v8i16,  Custom);
       setOperationAction(ISD::CTLZ,             MVT::v16i8,  Custom);
       setOperationAction(ISD::CTLZ,             MVT::v16i16, Custom);
       setOperationAction(ISD::CTLZ,             MVT::v32i8,  Custom);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i16,  Custom);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v16i8,  Custom);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v16i16, Custom);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v32i8,  Custom);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i16,  Expand);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v16i8,  Expand);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v16i16, Expand);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v32i8,  Expand);
 
       setOperationAction(ISD::CTTZ_ZERO_UNDEF,  MVT::v8i64,  Custom);
       setOperationAction(ISD::CTTZ_ZERO_UNDEF,  MVT::v16i32, Custom);
@@ -1545,10 +1545,10 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
         setOperationAction(ISD::CTLZ,             MVT::v8i32, Legal);
         setOperationAction(ISD::CTLZ,             MVT::v2i64, Legal);
         setOperationAction(ISD::CTLZ,             MVT::v4i32, Legal);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i64, Legal);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i32, Legal);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v2i64, Legal);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i32, Legal);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i64, Expand);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i32, Expand);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v2i64, Expand);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i32, Expand);
 
         setOperationAction(ISD::CTTZ_ZERO_UNDEF,  MVT::v4i64, Custom);
         setOperationAction(ISD::CTTZ_ZERO_UNDEF,  MVT::v8i32, Custom);
@@ -1559,10 +1559,10 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
         setOperationAction(ISD::CTLZ,             MVT::v8i32, Custom);
         setOperationAction(ISD::CTLZ,             MVT::v2i64, Custom);
         setOperationAction(ISD::CTLZ,             MVT::v4i32, Custom);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i64, Custom);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i32, Custom);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v2i64, Custom);
-        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i32, Custom);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i64, Expand);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v8i32, Expand);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v2i64, Expand);
+        setOperationAction(ISD::CTLZ_ZERO_UNDEF,  MVT::v4i32, Expand);
       }
     } // Subtarget->hasCDI()
 
@@ -1682,8 +1682,8 @@ X86TargetLowering::X86TargetLowering(const X86TargetMachine &TM,
     if (Subtarget->hasCDI()) {
       setOperationAction(ISD::CTLZ,            MVT::v32i16, Custom);
       setOperationAction(ISD::CTLZ,            MVT::v64i8,  Custom);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF, MVT::v32i16, Custom);
-      setOperationAction(ISD::CTLZ_ZERO_UNDEF, MVT::v64i8,  Custom);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF, MVT::v32i16, Expand);
+      setOperationAction(ISD::CTLZ_ZERO_UNDEF, MVT::v64i8,  Expand);
     }
 
     for (auto VT : { MVT::v64i8, MVT::v32i16 }) {
@@ -18001,9 +18001,6 @@ static SDValue LowerCTLZ_ZERO_UNDEF(SDValue Op, const X86Subtarget *Subtarget,
   unsigned NumBits = VT.getSizeInBits();
   SDLoc dl(Op);
 
-  if (VT.isVector() && Subtarget->hasAVX512())
-    return LowerVectorCTLZ_AVX512(Op, DAG);
-
   Op = Op.getOperand(0);
   if (VT == MVT::i8) {
     // Zero extend to i32 since there is not an i8 bsr.
diff --git a/llvm/lib/Target/X86/X86InstrAVX512.td b/llvm/lib/Target/X86/X86InstrAVX512.td
index cec95dc533e6..3310d36b84f6 100644
--- a/llvm/lib/Target/X86/X86InstrAVX512.td
+++ b/llvm/lib/Target/X86/X86InstrAVX512.td
@@ -7184,9 +7184,6 @@ def : Pat<(xor
 multiclass avx512_ctlz<bits<8> opc, string OpcodeStr, Predicate prd>{
 
   defm NAME :          avx512_unary_rm_vl_dq<opc, opc, OpcodeStr, ctlz, prd>;
-  let isCodeGenOnly = 1 in
-    defm NAME#_UNDEF : avx512_unary_rm_vl_dq<opc, opc, OpcodeStr,
-                                             ctlz_zero_undef, prd>;
 }
 
 defm VPLZCNT    : avx512_ctlz<0x44, "vplzcnt", HasCDI>;