diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypes.h
@@ -946,6 +946,7 @@
   // Widen Vector Result Promotion.
   void WidenVectorResult(SDNode *N, unsigned ResNo);
   SDValue WidenVecRes_MERGE_VALUES(SDNode* N, unsigned ResNo);
+  SDValue WidenVecRes_AssertZext(SDNode* N);
   SDValue WidenVecRes_BITCAST(SDNode* N);
   SDValue WidenVecRes_BUILD_VECTOR(SDNode* N);
   SDValue WidenVecRes_CONCAT_VECTORS(SDNode* N);
@@ -1075,6 +1076,7 @@
   // Generic Result Splitting.
   void SplitRes_MERGE_VALUES(SDNode *N, unsigned ResNo,
                              SDValue &Lo, SDValue &Hi);
+  void SplitVecRes_AssertZext  (SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitRes_ARITH_FENCE (SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitRes_Select      (SDNode *N, SDValue &Lo, SDValue &Hi);
   void SplitRes_SELECT_CC   (SDNode *N, SDValue &Lo, SDValue &Hi);
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeTypesGeneric.cpp
@@ -571,6 +571,16 @@
   Hi = DAG.getUNDEF(HiVT);
 }
 
+void DAGTypeLegalizer::SplitVecRes_AssertZext(SDNode *N, SDValue &Lo,
+                                              SDValue &Hi) {
+  SDValue L, H;
+  SDLoc dl(N);
+  GetSplitOp(N->getOperand(0), L, H);
+
+  Lo = DAG.getNode(ISD::AssertZext, dl, L.getValueType(), L, N->getOperand(1));
+  Hi = DAG.getNode(ISD::AssertZext, dl, H.getValueType(), H, N->getOperand(1));
+}
+
 void DAGTypeLegalizer::SplitRes_FREEZE(SDNode *N, SDValue &Lo, SDValue &Hi) {
   SDValue L, H;
   SDLoc dl(N);
diff --git a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/LegalizeVectorTypes.cpp
@@ -948,6 +948,7 @@
                        "operator!\n");
 
   case ISD::MERGE_VALUES: SplitRes_MERGE_VALUES(N, ResNo, Lo, Hi); break;
+  case ISD::AssertZext:   SplitVecRes_AssertZext(N, Lo, Hi); break;
   case ISD::VSELECT:
   case ISD::SELECT:
   case ISD::VP_MERGE:
@@ -3925,6 +3926,7 @@
     llvm_unreachable("Do not know how to widen the result of this operator!");
 
   case ISD::MERGE_VALUES:      Res = WidenVecRes_MERGE_VALUES(N, ResNo); break;
+  case ISD::AssertZext:        Res = WidenVecRes_AssertZext(N); break;
   case ISD::BITCAST:           Res = WidenVecRes_BITCAST(N); break;
   case ISD::BUILD_VECTOR:      Res = WidenVecRes_BUILD_VECTOR(N); break;
   case ISD::CONCAT_VECTORS:    Res = WidenVecRes_CONCAT_VECTORS(N); break;
@@ -5126,6 +5128,14 @@
   return DAG.getBuildVector(WidenVT, dl, Ops);
 }
 
+SDValue DAGTypeLegalizer::WidenVecRes_AssertZext(SDNode *N) {
+  SDValue InOp = ModifyToType(
+      N->getOperand(0),
+      TLI.getTypeToTransformTo(*DAG.getContext(), N->getValueType(0)), true);
+  return DAG.getNode(ISD::AssertZext, SDLoc(N), InOp.getValueType(), InOp,
+                     N->getOperand(1));
+}
+
 SDValue DAGTypeLegalizer::WidenVecRes_INSERT_VECTOR_ELT(SDNode *N) {
   SDValue InOp = GetWidenedVector(N->getOperand(0));
   return DAG.getNode(ISD::INSERT_VECTOR_ELT, SDLoc(N),
diff --git a/llvm/test/CodeGen/X86/legalize-vec-assertzext.ll b/llvm/test/CodeGen/X86/legalize-vec-assertzext.ll
new file mode 100644
--- /dev/null
+++ b/llvm/test/CodeGen/X86/legalize-vec-assertzext.ll
@@ -0,0 +1,39 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=x86_64-unknown-unknown -mattr=avx512f | FileCheck %s
+
+define i64 @split_assertzext(ptr %x) nounwind {
+; CHECK-LABEL: split_assertzext:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    pushq %rax
+; CHECK-NEXT:    callq test@PLT
+; CHECK-NEXT:    vextracti32x4 $3, %zmm1, %xmm0
+; CHECK-NEXT:    vpextrq $1, %xmm0, %rax
+; CHECK-NEXT:    popq %rcx
+; CHECK-NEXT:    vzeroupper
+; CHECK-NEXT:    retq
+  %e = call <16 x i64> @test(), !range !0
+  %d = extractelement <16 x i64> %e, i32 15
+  ret i64 %d
+}
+
+define i64 @widen_assertzext(ptr %x) nounwind {
+; CHECK-LABEL: widen_assertzext:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    pushq %rax
+; CHECK-NEXT:    callq test2@PLT
+; CHECK-NEXT:    movb $127, %al
+; CHECK-NEXT:    kmovw %eax, %k1
+; CHECK-NEXT:    vpexpandq %zmm0, %zmm0 {%k1} {z}
+; CHECK-NEXT:    vextracti32x4 $3, %zmm0, %xmm0
+; CHECK-NEXT:    vmovq %xmm0, %rax
+; CHECK-NEXT:    popq %rcx
+; CHECK-NEXT:    vzeroupper
+; CHECK-NEXT:    retq
+  %e = call <7 x i64> @test2(), !range !0
+  %d = extractelement <7 x i64> %e, i32 6
+  ret i64 %d
+}
+
+declare  <16 x i64> @test()
+declare  <7 x i64> @test2()
+!0 = !{ i64 0, i64 2 }