diff --git a/llvm/test/CodeGen/X86/lzcnt-cmp.ll b/llvm/test/CodeGen/X86/lzcnt-cmp.ll
new file mode 100644
index 00000000000000..435b09dd5d088b
--- /dev/null
+++ b/llvm/test/CodeGen/X86/lzcnt-cmp.ll
@@ -0,0 +1,258 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc < %s -mtriple=i686-- -mattr=+lzcnt | FileCheck %s --check-prefixes=X86
+; RUN: llc < %s -mtriple=x86_64-- -mattr=+lzcnt | FileCheck %s --check-prefix=X64
+
+define i1 @lshr_ctlz_cmpeq_one_i64(i64 %in) {
+; X86-LABEL: lshr_ctlz_cmpeq_one_i64:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    orl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    sete %al
+; X86-NEXT:    retl
+;
+; X64-LABEL: lshr_ctlz_cmpeq_one_i64:
+; X64:       # %bb.0:
+; X64-NEXT:    testq %rdi, %rdi
+; X64-NEXT:    sete %al
+; X64-NEXT:    retq
+  %ctlz = call i64 @llvm.ctlz.i64(i64 %in, i1 0)
+  %lshr = lshr i64 %ctlz, 6
+  %icmp = icmp eq i64 %lshr, 1
+  ret i1 %icmp
+}
+
+define i1 @lshr_ctlz_undef_cmpeq_one_i64(i64 %in) {
+; X86-LABEL: lshr_ctlz_undef_cmpeq_one_i64:
+; X86:       # %bb.0:
+; X86-NEXT:    xorl %eax, %eax
+; X86-NEXT:    cmpl $0, {{[0-9]+}}(%esp)
+; X86-NEXT:    jne .LBB1_2
+; X86-NEXT:  # %bb.1:
+; X86-NEXT:    lzcntl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    addl $32, %eax
+; X86-NEXT:  .LBB1_2:
+; X86-NEXT:    testb $64, %al
+; X86-NEXT:    setne %al
+; X86-NEXT:    retl
+;
+; X64-LABEL: lshr_ctlz_undef_cmpeq_one_i64:
+; X64:       # %bb.0:
+; X64-NEXT:    lzcntq %rdi, %rax
+; X64-NEXT:    shrq $6, %rax
+; X64-NEXT:    cmpl $1, %eax
+; X64-NEXT:    sete %al
+; X64-NEXT:    retq
+  %ctlz = call i64 @llvm.ctlz.i64(i64 %in, i1 -1)
+  %lshr = lshr i64 %ctlz, 6
+  %icmp = icmp eq i64 %lshr, 1
+  ret i1 %icmp
+}
+
+define i1 @lshr_ctlz_cmpne_zero_i64(i64 %in) {
+; X86-LABEL: lshr_ctlz_cmpne_zero_i64:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    orl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    sete %al
+; X86-NEXT:    retl
+;
+; X64-LABEL: lshr_ctlz_cmpne_zero_i64:
+; X64:       # %bb.0:
+; X64-NEXT:    testq %rdi, %rdi
+; X64-NEXT:    sete %al
+; X64-NEXT:    retq
+  %ctlz = call i64 @llvm.ctlz.i64(i64 %in, i1 0)
+  %lshr = lshr i64 %ctlz, 6
+  %icmp = icmp ne i64 %lshr, 0
+  ret i1 %icmp
+}
+
+define i1 @lshr_ctlz_undef_cmpne_zero_i64(i64 %in) {
+; X86-LABEL: lshr_ctlz_undef_cmpne_zero_i64:
+; X86:       # %bb.0:
+; X86-NEXT:    xorl %eax, %eax
+; X86-NEXT:    cmpl $0, {{[0-9]+}}(%esp)
+; X86-NEXT:    jne .LBB3_2
+; X86-NEXT:  # %bb.1:
+; X86-NEXT:    lzcntl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    addl $32, %eax
+; X86-NEXT:  .LBB3_2:
+; X86-NEXT:    testb $64, %al
+; X86-NEXT:    setne %al
+; X86-NEXT:    retl
+;
+; X64-LABEL: lshr_ctlz_undef_cmpne_zero_i64:
+; X64:       # %bb.0:
+; X64-NEXT:    lzcntq %rdi, %rax
+; X64-NEXT:    testb $64, %al
+; X64-NEXT:    setne %al
+; X64-NEXT:    retq
+  %ctlz = call i64 @llvm.ctlz.i64(i64 %in, i1 -1)
+  %lshr = lshr i64 %ctlz, 6
+  %icmp = icmp ne i64 %lshr, 0
+  ret i1 %icmp
+}
+
+define <2 x i64> @lshr_ctlz_cmpeq_zero_v2i64(<2 x i64> %in) {
+; X86-LABEL: lshr_ctlz_cmpeq_zero_v2i64:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    xorl %edx, %edx
+; X86-NEXT:    cmpl $0, {{[0-9]+}}(%esp)
+; X86-NEXT:    movl $0, %ecx
+; X86-NEXT:    jne .LBB4_2
+; X86-NEXT:  # %bb.1:
+; X86-NEXT:    lzcntl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    addl $32, %ecx
+; X86-NEXT:  .LBB4_2:
+; X86-NEXT:    cmpl $0, {{[0-9]+}}(%esp)
+; X86-NEXT:    jne .LBB4_4
+; X86-NEXT:  # %bb.3:
+; X86-NEXT:    lzcntl {{[0-9]+}}(%esp), %edx
+; X86-NEXT:    addl $32, %edx
+; X86-NEXT:  .LBB4_4:
+; X86-NEXT:    andl $-64, %edx
+; X86-NEXT:    cmpl $1, %edx
+; X86-NEXT:    sbbl %edx, %edx
+; X86-NEXT:    andl $-64, %ecx
+; X86-NEXT:    cmpl $1, %ecx
+; X86-NEXT:    sbbl %ecx, %ecx
+; X86-NEXT:    movl %ecx, 12(%eax)
+; X86-NEXT:    movl %ecx, 8(%eax)
+; X86-NEXT:    movl %edx, 4(%eax)
+; X86-NEXT:    movl %edx, (%eax)
+; X86-NEXT:    retl $4
+;
+; X64-LABEL: lshr_ctlz_cmpeq_zero_v2i64:
+; X64:       # %bb.0:
+; X64-NEXT:    movdqa %xmm0, %xmm1
+; X64-NEXT:    psrlq $1, %xmm1
+; X64-NEXT:    por %xmm0, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm0
+; X64-NEXT:    psrlq $2, %xmm0
+; X64-NEXT:    por %xmm1, %xmm0
+; X64-NEXT:    movdqa %xmm0, %xmm1
+; X64-NEXT:    psrlq $4, %xmm1
+; X64-NEXT:    por %xmm0, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm0
+; X64-NEXT:    psrlq $8, %xmm0
+; X64-NEXT:    por %xmm1, %xmm0
+; X64-NEXT:    movdqa %xmm0, %xmm1
+; X64-NEXT:    psrlq $16, %xmm1
+; X64-NEXT:    por %xmm0, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm0
+; X64-NEXT:    psrlq $32, %xmm0
+; X64-NEXT:    por %xmm1, %xmm0
+; X64-NEXT:    pcmpeqd %xmm1, %xmm1
+; X64-NEXT:    pxor %xmm0, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm0
+; X64-NEXT:    psrlw $1, %xmm0
+; X64-NEXT:    pand {{.*}}(%rip), %xmm0
+; X64-NEXT:    psubb %xmm0, %xmm1
+; X64-NEXT:    movdqa {{.*#+}} xmm0 = [51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51]
+; X64-NEXT:    movdqa %xmm1, %xmm2
+; X64-NEXT:    pand %xmm0, %xmm2
+; X64-NEXT:    psrlw $2, %xmm1
+; X64-NEXT:    pand %xmm0, %xmm1
+; X64-NEXT:    paddb %xmm2, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm2
+; X64-NEXT:    psrlw $4, %xmm2
+; X64-NEXT:    paddb %xmm1, %xmm2
+; X64-NEXT:    pand {{.*}}(%rip), %xmm2
+; X64-NEXT:    pxor %xmm0, %xmm0
+; X64-NEXT:    psadbw %xmm0, %xmm2
+; X64-NEXT:    psrlq $6, %xmm2
+; X64-NEXT:    pcmpeqd %xmm0, %xmm2
+; X64-NEXT:    pshufd {{.*#+}} xmm0 = xmm2[1,0,3,2]
+; X64-NEXT:    pand %xmm2, %xmm0
+; X64-NEXT:    retq
+  %ctlz = call <2 x i64> @llvm.ctlz.v2i64(<2 x i64> %in, i1 0)
+  %lshr = lshr <2 x i64> %ctlz, <i64 6, i64 6>
+  %icmp = icmp eq <2 x i64> %lshr, zeroinitializer
+  %sext = sext <2 x i1> %icmp to <2 x i64>
+  ret <2 x i64> %sext
+}
+
+define <2 x i64> @lshr_ctlz_cmpne_zero_v2i64(<2 x i64> %in) {
+; X86-LABEL: lshr_ctlz_cmpne_zero_v2i64:
+; X86:       # %bb.0:
+; X86-NEXT:    movl {{[0-9]+}}(%esp), %eax
+; X86-NEXT:    xorl %edx, %edx
+; X86-NEXT:    cmpl $0, {{[0-9]+}}(%esp)
+; X86-NEXT:    movl $0, %ecx
+; X86-NEXT:    jne .LBB5_2
+; X86-NEXT:  # %bb.1:
+; X86-NEXT:    lzcntl {{[0-9]+}}(%esp), %ecx
+; X86-NEXT:    addl $32, %ecx
+; X86-NEXT:  .LBB5_2:
+; X86-NEXT:    cmpl $0, {{[0-9]+}}(%esp)
+; X86-NEXT:    jne .LBB5_4
+; X86-NEXT:  # %bb.3:
+; X86-NEXT:    lzcntl {{[0-9]+}}(%esp), %edx
+; X86-NEXT:    addl $32, %edx
+; X86-NEXT:  .LBB5_4:
+; X86-NEXT:    andl $-64, %edx
+; X86-NEXT:    negl %edx
+; X86-NEXT:    sbbl %edx, %edx
+; X86-NEXT:    andl $-64, %ecx
+; X86-NEXT:    negl %ecx
+; X86-NEXT:    sbbl %ecx, %ecx
+; X86-NEXT:    movl %ecx, 12(%eax)
+; X86-NEXT:    movl %ecx, 8(%eax)
+; X86-NEXT:    movl %edx, 4(%eax)
+; X86-NEXT:    movl %edx, (%eax)
+; X86-NEXT:    retl $4
+;
+; X64-LABEL: lshr_ctlz_cmpne_zero_v2i64:
+; X64:       # %bb.0:
+; X64-NEXT:    movdqa %xmm0, %xmm1
+; X64-NEXT:    psrlq $1, %xmm1
+; X64-NEXT:    por %xmm0, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm0
+; X64-NEXT:    psrlq $2, %xmm0
+; X64-NEXT:    por %xmm1, %xmm0
+; X64-NEXT:    movdqa %xmm0, %xmm1
+; X64-NEXT:    psrlq $4, %xmm1
+; X64-NEXT:    por %xmm0, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm0
+; X64-NEXT:    psrlq $8, %xmm0
+; X64-NEXT:    por %xmm1, %xmm0
+; X64-NEXT:    movdqa %xmm0, %xmm1
+; X64-NEXT:    psrlq $16, %xmm1
+; X64-NEXT:    por %xmm0, %xmm1
+; X64-NEXT:    movdqa %xmm1, %xmm2
+; X64-NEXT:    psrlq $32, %xmm2
+; X64-NEXT:    por %xmm1, %xmm2
+; X64-NEXT:    pcmpeqd %xmm1, %xmm1
+; X64-NEXT:    pxor %xmm1, %xmm2
+; X64-NEXT:    movdqa %xmm2, %xmm0
+; X64-NEXT:    psrlw $1, %xmm0
+; X64-NEXT:    pand {{.*}}(%rip), %xmm0
+; X64-NEXT:    psubb %xmm0, %xmm2
+; X64-NEXT:    movdqa {{.*#+}} xmm0 = [51,51,51,51,51,51,51,51,51,51,51,51,51,51,51,51]
+; X64-NEXT:    movdqa %xmm2, %xmm3
+; X64-NEXT:    pand %xmm0, %xmm3
+; X64-NEXT:    psrlw $2, %xmm2
+; X64-NEXT:    pand %xmm0, %xmm2
+; X64-NEXT:    paddb %xmm3, %xmm2
+; X64-NEXT:    movdqa %xmm2, %xmm0
+; X64-NEXT:    psrlw $4, %xmm0
+; X64-NEXT:    paddb %xmm2, %xmm0
+; X64-NEXT:    pand {{.*}}(%rip), %xmm0
+; X64-NEXT:    pxor %xmm2, %xmm2
+; X64-NEXT:    psadbw %xmm2, %xmm0
+; X64-NEXT:    psrlq $6, %xmm0
+; X64-NEXT:    pcmpeqd %xmm2, %xmm0
+; X64-NEXT:    pshufd {{.*#+}} xmm2 = xmm0[1,0,3,2]
+; X64-NEXT:    pand %xmm2, %xmm0
+; X64-NEXT:    pxor %xmm1, %xmm0
+; X64-NEXT:    retq
+  %ctlz = call <2 x i64> @llvm.ctlz.v2i64(<2 x i64> %in, i1 0)
+  %lshr = lshr <2 x i64> %ctlz, <i64 6, i64 6>
+  %icmp = icmp ne <2 x i64> %lshr, zeroinitializer
+  %sext = sext <2 x i1> %icmp to <2 x i64>
+  ret <2 x i64> %sext
+}
+
+declare i64 @llvm.ctlz.i64(i64, i1)
+declare <2 x i64> @llvm.ctlz.v2i64(<2 x i64>, i1)