Index: lib/Target/X86/X86InstrAVX512.td
===================================================================
--- lib/Target/X86/X86InstrAVX512.td
+++ lib/Target/X86/X86InstrAVX512.td
@@ -2458,7 +2458,7 @@
                             HasBWI>, VEX, PS, VEX_W;
 }
 
-defm KNOT : avx512_mask_unop_all<0x44, "knot", not>;
+defm KNOT : avx512_mask_unop_all<0x44, "knot", null_frag>;
 
 multiclass avx512_mask_unop_int<string IntName, string InstName> {
   let Predicates = [HasAVX512] in
@@ -2516,14 +2516,11 @@
                              HasBWI, IsCommutable>, VEX_4V, VEX_L, VEX_W, PS;
 }
 
-def andn : PatFrag<(ops node:$i0, node:$i1), (and (not node:$i0), node:$i1)>;
-def xnor : PatFrag<(ops node:$i0, node:$i1), (not (xor node:$i0, node:$i1))>;
-
 defm KAND  : avx512_mask_binop_all<0x41, "kand",  and,  1>;
 defm KOR   : avx512_mask_binop_all<0x45, "kor",   or,   1>;
-defm KXNOR : avx512_mask_binop_all<0x46, "kxnor", xnor, 1>;
+defm KXNOR : avx512_mask_binop_all<0x46, "kxnor", null_frag, 1>;
 defm KXOR  : avx512_mask_binop_all<0x47, "kxor",  xor,  1>;
-defm KANDN : avx512_mask_binop_all<0x42, "kandn", andn, 0>;
+defm KANDN : avx512_mask_binop_all<0x42, "kandn", null_frag, 0>;
 defm KADD  : avx512_mask_binop_all<0x4A, "kadd",  add,  1, HasDQI>;
 
 multiclass avx512_mask_binop_int<string IntName, string InstName> {
@@ -2566,11 +2563,35 @@
 }
 
 defm : avx512_binop_pat<and,  KANDWrr>;
-defm : avx512_binop_pat<andn, KANDNWrr>;
 defm : avx512_binop_pat<or,   KORWrr>;
-defm : avx512_binop_pat<xnor, KXNORWrr>;
 defm : avx512_binop_pat<xor,  KXORWrr>;
 
+def : Pat<(and VK16:$src1, (xor VK16:$src2, (v16i1 immAllOnesV))),
+          (KANDNWrr VK16:$src1, VK16:$src2)>;
+def : Pat<(and VK8:$src1, (xor VK8:$src2, (v8i1 immAllOnesV))),
+          (KANDNBrr VK8:$src1, VK8:$src2)>, Requires<[HasDQI]>;
+def : Pat<(and VK32:$src1, (xor VK32:$src2, (v32i1 immAllOnesV))),
+          (KANDNDrr VK32:$src1, VK32:$src2)>, Requires<[HasBWI]>;
+def : Pat<(and VK64:$src1, (xor VK64:$src2, (v64i1 immAllOnesV))),
+          (KANDNQrr VK64:$src1, VK64:$src2)>, Requires<[HasBWI]>;
+
+let Predicates = [NoDQI] in
+def : Pat<(and VK8:$src1, (xor VK8:$src2, (v8i1 immAllOnesV))),
+          (COPY_TO_REGCLASS (KANDNWrr (COPY_TO_REGCLASS VK8:$src1, VK16),
+                             (COPY_TO_REGCLASS VK8:$src2, VK16)), VK8)>;
+
+def : Pat<(and VK4:$src1, (xor VK4:$src2, (v4i1 immAllOnesV))),
+          (COPY_TO_REGCLASS (KANDNWrr (COPY_TO_REGCLASS VK4:$src1, VK16),
+                             (COPY_TO_REGCLASS VK4:$src2, VK16)), VK4)>;
+
+def : Pat<(and VK2:$src1, (xor VK2:$src2, (v2i1 immAllOnesV))),
+          (COPY_TO_REGCLASS (KANDNWrr (COPY_TO_REGCLASS VK2:$src1, VK16),
+                             (COPY_TO_REGCLASS VK2:$src2, VK16)), VK2)>;
+
+def : Pat<(and VK1:$src1, (xor VK1:$src2, (i1 1))),
+          (COPY_TO_REGCLASS (KANDNWrr (COPY_TO_REGCLASS VK1:$src1, VK16),
+                             (COPY_TO_REGCLASS VK1:$src2, VK16)), VK1)>;
+
 def : Pat<(xor (xor VK16:$src1, VK16:$src2), (v16i1 immAllOnesV)),
           (KXNORWrr VK16:$src1, VK16:$src2)>;
 def : Pat<(xor (xor VK8:$src1, VK8:$src2), (v8i1 immAllOnesV)),
Index: test/CodeGen/X86/avx512-mask-op.ll
===================================================================
--- test/CodeGen/X86/avx512-mask-op.ll
+++ test/CodeGen/X86/avx512-mask-op.ll
@@ -257,9 +257,9 @@
 ;
 ; SKX-LABEL: test4:
 ; SKX:       ## BB#0:
-; SKX-NEXT:    vpcmpgtq %ymm3, %ymm2, %k0
-; SKX-NEXT:    knotw %k0, %k1
-; SKX-NEXT:    vpcmpgtq %ymm1, %ymm0, %k0 {%k1}
+; SKX-NEXT:    vpcmpgtq %ymm1, %ymm0, %k0
+; SKX-NEXT:    vpcmpgtq %ymm3, %ymm2, %k1
+; SKX-NEXT:    kandnw %k1, %k0, %k0
 ; SKX-NEXT:    vpmovm2d %k0, %xmm0
 ; SKX-NEXT:    retq
   %x_gt_y = icmp sgt <4 x i64> %x, %y
@@ -280,8 +280,8 @@
 ; SKX-LABEL: test5:
 ; SKX:       ## BB#0:
 ; SKX-NEXT:    vpcmpgtq %xmm0, %xmm1, %k0
-; SKX-NEXT:    knotw %k0, %k1
-; SKX-NEXT:    vpcmpgtq %xmm3, %xmm2, %k0 {%k1}
+; SKX-NEXT:    vpcmpgtq %xmm3, %xmm2, %k1
+; SKX-NEXT:    kandnw %k0, %k1, %k0
 ; SKX-NEXT:    vpmovm2q %k0, %xmm0
 ; SKX-NEXT:    retq
   %x_gt_y = icmp slt <2 x i64> %x, %y
Index: test/CodeGen/X86/avx512-select.ll
===================================================================
--- test/CodeGen/X86/avx512-select.ll
+++ test/CodeGen/X86/avx512-select.ll
@@ -133,10 +133,9 @@
 ; CHECK-NEXT:    kmovw %edx, %k0
 ; CHECK-NEXT:    kmovw %edi, %k1
 ; CHECK-NEXT:    kmovw %esi, %k2
-; CHECK-NEXT:    kandw %k0, %k1, %k1
-; CHECK-NEXT:    knotw %k0, %k0
-; CHECK-NEXT:    kandw %k0, %k2, %k0
-; CHECK-NEXT:    korw %k0, %k1, %k0
+; CHECK-NEXT:    kandnw %k0, %k2, %k2
+; CHECK-NEXT:    kandw %k0, %k1, %k0
+; CHECK-NEXT:    korw %k2, %k0, %k0
 ; CHECK-NEXT:    kmovw %k0, %eax
 ; CHECK-NEXT:    retq
   %mask = bitcast i8 %m to <8 x i1>