Index: llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
===================================================================
--- llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
+++ llvm/lib/CodeGen/SelectionDAG/TargetLowering.cpp
@@ -3156,23 +3156,28 @@
   if (!N)
     return false;
 
+  unsigned EltWidth;
   APInt CVal;
   if (auto *CN = dyn_cast<ConstantSDNode>(N)) {
     CVal = CN->getAPIntValue();
+    EltWidth = CVal.getBitWidth();
   } else if (auto *BV = dyn_cast<BuildVectorSDNode>(N)) {
     auto *CN = BV->getConstantSplatNode();
     if (!CN)
       return false;
-
-    // If this is a truncating build vector, truncate the splat value.
-    // Otherwise, we may fail to match the expected values below.
-    unsigned BVEltWidth = BV->getValueType(0).getScalarSizeInBits();
+    EltWidth = BV->getValueType(0).getScalarSizeInBits();
     CVal = CN->getAPIntValue();
-    if (BVEltWidth < CVal.getBitWidth())
-      CVal = CVal.trunc(BVEltWidth);
-  } else {
+  } else if (N->getOpcode() == ISD::SPLAT_VECTOR &&
+             isa<ConstantSDNode>(N->getOperand(0))) {
+    EltWidth = N->getValueType(0).getScalarSizeInBits();
+    CVal = cast<ConstantSDNode>(N->getOperand(0))->getAPIntValue();
+  } else
     return false;
-  }
+
+  // If this is a truncating splat, truncate the splat value.
+  // Otherwise, we may fail to match the expected values below.
+  if (EltWidth < CVal.getBitWidth())
+    CVal = CVal.trunc(EltWidth);
 
   switch (getBooleanContents(N->getValueType(0))) {
   case UndefinedBooleanContent:
Index: llvm/test/CodeGen/AArch64/sve-cmp-folds.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/AArch64/sve-cmp-folds.ll
@@ -0,0 +1,54 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=aarch64-linux-unknown -mattr=+sve -o - < %s | FileCheck %s
+
+define <vscale x 8 x i1> @not_icmp_sle_nxv8i16(<vscale x 8 x i16> %a, <vscale x 8 x i16> %b) {
+; CHECK-LABEL: not_icmp_sle_nxv8i16:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ptrue p0.h
+; CHECK-NEXT:    cmpgt p0.h, p0/z, z0.h, z1.h
+; CHECK-NEXT:    ret
+  %icmp = icmp sle <vscale x 8 x i16> %a, %b
+  %tmp = insertelement <vscale x 8 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 8 x i1> %tmp, <vscale x 8 x i1> undef, <vscale x 8 x i32> zeroinitializer
+  %not = xor <vscale x 8 x i1> %ones, %icmp
+  ret <vscale x 8 x i1> %not
+}
+
+define <vscale x 4 x i1> @not_icmp_sgt_nxv4i32(<vscale x 4 x i32> %a, <vscale x 4 x i32> %b) {
+; CHECK-LABEL: not_icmp_sgt_nxv4i32:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    cmpge p0.s, p0/z, z1.s, z0.s
+; CHECK-NEXT:    ret
+  %icmp = icmp sgt <vscale x 4 x i32> %a, %b
+  %tmp = insertelement <vscale x 4 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 4 x i1> %tmp, <vscale x 4 x i1> undef, <vscale x 4 x i32> zeroinitializer
+  %not = xor <vscale x 4 x i1> %icmp, %ones
+  ret <vscale x 4 x i1> %not
+}
+
+define <vscale x 2 x i1> @not_fcmp_une_nxv2f64(<vscale x 2 x double> %a, <vscale x 2 x double> %b) {
+; CHECK-LABEL: not_fcmp_une_nxv2f64:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ptrue p0.d
+; CHECK-NEXT:    fcmeq p0.d, p0/z, z0.d, z1.d
+; CHECK-NEXT:    ret
+  %icmp = fcmp une <vscale x 2 x double> %a, %b
+  %tmp = insertelement <vscale x 2 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 2 x i1> %tmp, <vscale x 2 x i1> undef, <vscale x 2 x i32> zeroinitializer
+  %not = xor <vscale x 2 x i1> %icmp, %ones
+  ret <vscale x 2 x i1> %not
+}
+
+define <vscale x 4 x i1> @not_fcmp_uge_nxv4f32(<vscale x 4 x float> %a, <vscale x 4 x float> %b) {
+; CHECK-LABEL: not_fcmp_uge_nxv4f32:
+; CHECK:       // %bb.0:
+; CHECK-NEXT:    ptrue p0.s
+; CHECK-NEXT:    fcmgt p0.s, p0/z, z1.s, z0.s
+; CHECK-NEXT:    ret
+  %icmp = fcmp uge <vscale x 4 x float> %a, %b
+  %tmp = insertelement <vscale x 4 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 4 x i1> %tmp, <vscale x 4 x i1> undef, <vscale x 4 x i32> zeroinitializer
+  %not = xor <vscale x 4 x i1> %icmp, %ones
+  ret <vscale x 4 x i1> %not
+}
Index: llvm/test/CodeGen/RISCV/rvv/cmp-folds.ll
===================================================================
--- /dev/null
+++ llvm/test/CodeGen/RISCV/rvv/cmp-folds.ll
@@ -0,0 +1,57 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -mattr=+d,+experimental-zfh,+experimental-v \
+; RUN:     -verify-machineinstrs < %s | FileCheck %s
+; RUN: llc -mtriple=riscv64 -mattr=+d,+experimental-zfh,+experimental-v \
+; RUN:     -verify-machineinstrs < %s | FileCheck %s
+
+define <vscale x 8 x i1> @not_icmp_sle_nxv8i16(<vscale x 8 x i16> %a, <vscale x 8 x i16> %b) {
+; CHECK-LABEL: not_icmp_sle_nxv8i16:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetvli a0, zero, e16, m2, ta, mu
+; CHECK-NEXT:    vmslt.vv v0, v10, v8
+; CHECK-NEXT:    ret
+  %icmp = icmp sle <vscale x 8 x i16> %a, %b
+  %tmp = insertelement <vscale x 8 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 8 x i1> %tmp, <vscale x 8 x i1> undef, <vscale x 8 x i32> zeroinitializer
+  %not = xor <vscale x 8 x i1> %ones, %icmp
+  ret <vscale x 8 x i1> %not
+}
+
+define <vscale x 4 x i1> @not_icmp_sgt_nxv4i32(<vscale x 4 x i32> %a, <vscale x 4 x i32> %b) {
+; CHECK-LABEL: not_icmp_sgt_nxv4i32:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetvli a0, zero, e32, m2, ta, mu
+; CHECK-NEXT:    vmsle.vv v0, v8, v10
+; CHECK-NEXT:    ret
+  %icmp = icmp sgt <vscale x 4 x i32> %a, %b
+  %tmp = insertelement <vscale x 4 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 4 x i1> %tmp, <vscale x 4 x i1> undef, <vscale x 4 x i32> zeroinitializer
+  %not = xor <vscale x 4 x i1> %icmp, %ones
+  ret <vscale x 4 x i1> %not
+}
+
+define <vscale x 2 x i1> @not_fcmp_une_nxv2f64(<vscale x 2 x double> %a, <vscale x 2 x double> %b) {
+; CHECK-LABEL: not_fcmp_une_nxv2f64:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetvli a0, zero, e64, m2, ta, mu
+; CHECK-NEXT:    vmfeq.vv v0, v8, v10
+; CHECK-NEXT:    ret
+  %icmp = fcmp une <vscale x 2 x double> %a, %b
+  %tmp = insertelement <vscale x 2 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 2 x i1> %tmp, <vscale x 2 x i1> undef, <vscale x 2 x i32> zeroinitializer
+  %not = xor <vscale x 2 x i1> %icmp, %ones
+  ret <vscale x 2 x i1> %not
+}
+
+define <vscale x 4 x i1> @not_fcmp_uge_nxv4f32(<vscale x 4 x float> %a, <vscale x 4 x float> %b) {
+; CHECK-LABEL: not_fcmp_uge_nxv4f32:
+; CHECK:       # %bb.0:
+; CHECK-NEXT:    vsetvli a0, zero, e32, m2, ta, mu
+; CHECK-NEXT:    vmflt.vv v0, v8, v10
+; CHECK-NEXT:    ret
+  %icmp = fcmp uge <vscale x 4 x float> %a, %b
+  %tmp = insertelement <vscale x 4 x i1> undef, i1 true, i32 0
+  %ones = shufflevector <vscale x 4 x i1> %tmp, <vscale x 4 x i1> undef, <vscale x 4 x i32> zeroinitializer
+  %not = xor <vscale x 4 x i1> %icmp, %ones
+  ret <vscale x 4 x i1> %not
+}