diff --git a/llvm/lib/Target/ARM/ARMISelLowering.cpp b/llvm/lib/Target/ARM/ARMISelLowering.cpp
--- a/llvm/lib/Target/ARM/ARMISelLowering.cpp
+++ b/llvm/lib/Target/ARM/ARMISelLowering.cpp
@@ -14695,18 +14695,22 @@
   // use the VMOVN over splitting the store. We are looking for patterns of:
   // !rev: 0 N 1 N+1 2 N+2 ...
   //  rev: N 0 N+1 1 N+2 2 ...
-  auto isVMOVNOriginalMask = [&](ArrayRef<int> M, bool rev) {
+  // The shuffle may either be a single source (in which case N = NumElts/2) or
+  // two inputs extended with concat to the same size (in which case N =
+  // NumElts).
+  auto isVMOVNShuffle = [&](ShuffleVectorSDNode *SVN, bool Rev) {
+    ArrayRef<int> M = SVN->getMask();
     unsigned NumElts = ToVT.getVectorNumElements();
-    if (NumElts != M.size())
-      return false;
+    if (SVN->getOperand(1).isUndef())
+      NumElts /= 2;
 
-    unsigned Off0 = rev ? NumElts : 0;
-    unsigned Off1 = rev ? 0 : NumElts;
+    unsigned Off0 = Rev ? NumElts : 0;
+    unsigned Off1 = Rev ? 0 : NumElts;
 
-    for (unsigned i = 0; i < NumElts; i += 2) {
-      if (M[i] >= 0 && M[i] != (int)(Off0 + i / 2))
+    for (unsigned I = 0; I < NumElts; I += 2) {
+      if (M[I] >= 0 && M[I] != (int)(Off0 + I / 2))
         return false;
-      if (M[i + 1] >= 0 && M[i + 1] != (int)(Off1 + i / 2))
+      if (M[I + 1] >= 0 && M[I + 1] != (int)(Off1 + I / 2))
         return false;
     }
 
@@ -14721,9 +14725,8 @@
       return SDValue();
     }
   }
-  if (auto *Shuffle = dyn_cast<ShuffleVectorSDNode>(Trunc->getOperand(0)))
-    if (isVMOVNOriginalMask(Shuffle->getMask(), false) ||
-        isVMOVNOriginalMask(Shuffle->getMask(), true))
+  if (auto *Shuffle = dyn_cast<ShuffleVectorSDNode>(Trunc.getOperand(0)))
+    if (isVMOVNShuffle(Shuffle, false) || isVMOVNShuffle(Shuffle, true))
       return SDValue();
 
   LLVMContext &C = *DAG.getContext();
diff --git a/llvm/test/CodeGen/Thumb2/mve-vmovnstore.ll b/llvm/test/CodeGen/Thumb2/mve-vmovnstore.ll
--- a/llvm/test/CodeGen/Thumb2/mve-vmovnstore.ll
+++ b/llvm/test/CodeGen/Thumb2/mve-vmovnstore.ll
@@ -30,16 +30,8 @@
 define arm_aapcs_vfpcc void @vmovn32_trunc1_onesrc(<8 x i32> %src1, <8 x i16> *%dest) {
 ; CHECK-LABEL: vmovn32_trunc1_onesrc:
 ; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    vmov.f32 s8, s2
-; CHECK-NEXT:    vmov.f32 s9, s6
-; CHECK-NEXT:    vmov.f32 s10, s3
-; CHECK-NEXT:    vmov.f32 s11, s7
-; CHECK-NEXT:    vstrh.32 q2, [r0, #8]
-; CHECK-NEXT:    vmov.f32 s8, s0
-; CHECK-NEXT:    vmov.f32 s9, s4
-; CHECK-NEXT:    vmov.f32 s10, s1
-; CHECK-NEXT:    vmov.f32 s11, s5
-; CHECK-NEXT:    vstrh.32 q2, [r0]
+; CHECK-NEXT:    vmovnt.i32 q0, q1
+; CHECK-NEXT:    vstrw.32 q0, [r0]
 ; CHECK-NEXT:    bx lr
 entry:
   %strided.vec = shufflevector <8 x i32> %src1, <8 x i32> undef, <8 x i32> <i32 0, i32 4, i32 1, i32 5, i32 2, i32 6, i32 3, i32 7>
@@ -51,16 +43,8 @@
 define arm_aapcs_vfpcc void @vmovn32_trunc2_onesrc(<8 x i32> %src1, <8 x i16> *%dest) {
 ; CHECK-LABEL: vmovn32_trunc2_onesrc:
 ; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    vmov.f32 s8, s6
-; CHECK-NEXT:    vmov.f32 s9, s2
-; CHECK-NEXT:    vmov.f32 s10, s7
-; CHECK-NEXT:    vmov.f32 s11, s3
-; CHECK-NEXT:    vstrh.32 q2, [r0, #8]
-; CHECK-NEXT:    vmov.f32 s8, s4
-; CHECK-NEXT:    vmov.f32 s9, s0
-; CHECK-NEXT:    vmov.f32 s10, s5
-; CHECK-NEXT:    vmov.f32 s11, s1
-; CHECK-NEXT:    vstrh.32 q2, [r0]
+; CHECK-NEXT:    vmovnt.i32 q1, q0
+; CHECK-NEXT:    vstrw.32 q1, [r0]
 ; CHECK-NEXT:    bx lr
 entry:
   %strided.vec = shufflevector <8 x i32> %src1, <8 x i32> undef, <8 x i32> <i32 4, i32 0, i32 5, i32 1, i32 6, i32 2, i32 7, i32 3>
@@ -98,40 +82,8 @@
 define arm_aapcs_vfpcc void @vmovn16_trunc1_onesrc(<16 x i16> %src1, <16 x i8> *%dest) {
 ; CHECK-LABEL: vmovn16_trunc1_onesrc:
 ; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    vmov.u16 r1, q0[4]
-; CHECK-NEXT:    vmov.16 q2[0], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[4]
-; CHECK-NEXT:    vmov.16 q2[1], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[5]
-; CHECK-NEXT:    vmov.16 q2[2], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[5]
-; CHECK-NEXT:    vmov.16 q2[3], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[6]
-; CHECK-NEXT:    vmov.16 q2[4], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[6]
-; CHECK-NEXT:    vmov.16 q2[5], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[7]
-; CHECK-NEXT:    vmov.16 q2[6], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[7]
-; CHECK-NEXT:    vmov.16 q2[7], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[0]
-; CHECK-NEXT:    vstrb.16 q2, [r0, #8]
-; CHECK-NEXT:    vmov.16 q2[0], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[0]
-; CHECK-NEXT:    vmov.16 q2[1], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[1]
-; CHECK-NEXT:    vmov.16 q2[2], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[1]
-; CHECK-NEXT:    vmov.16 q2[3], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[2]
-; CHECK-NEXT:    vmov.16 q2[4], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[2]
-; CHECK-NEXT:    vmov.16 q2[5], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[3]
-; CHECK-NEXT:    vmov.16 q2[6], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[3]
-; CHECK-NEXT:    vmov.16 q2[7], r1
-; CHECK-NEXT:    vstrb.16 q2, [r0]
+; CHECK-NEXT:    vmovnt.i16 q0, q1
+; CHECK-NEXT:    vstrw.32 q0, [r0]
 ; CHECK-NEXT:    bx lr
 entry:
   %strided.vec = shufflevector <16 x i16> %src1, <16 x i16> undef, <16 x i32> <i32 0, i32 8, i32 1, i32 9, i32 2, i32 10, i32 3, i32 11, i32 4, i32 12, i32 5, i32 13, i32 6, i32 14, i32 7, i32 15>
@@ -143,40 +95,8 @@
 define arm_aapcs_vfpcc void @vmovn16_trunc2_onesrc(<16 x i16> %src1, <16 x i8> *%dest) {
 ; CHECK-LABEL: vmovn16_trunc2_onesrc:
 ; CHECK:       @ %bb.0: @ %entry
-; CHECK-NEXT:    vmov.u16 r1, q1[4]
-; CHECK-NEXT:    vmov.16 q2[0], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[4]
-; CHECK-NEXT:    vmov.16 q2[1], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[5]
-; CHECK-NEXT:    vmov.16 q2[2], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[5]
-; CHECK-NEXT:    vmov.16 q2[3], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[6]
-; CHECK-NEXT:    vmov.16 q2[4], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[6]
-; CHECK-NEXT:    vmov.16 q2[5], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[7]
-; CHECK-NEXT:    vmov.16 q2[6], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[7]
-; CHECK-NEXT:    vmov.16 q2[7], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[0]
-; CHECK-NEXT:    vstrb.16 q2, [r0, #8]
-; CHECK-NEXT:    vmov.16 q2[0], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[0]
-; CHECK-NEXT:    vmov.16 q2[1], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[1]
-; CHECK-NEXT:    vmov.16 q2[2], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[1]
-; CHECK-NEXT:    vmov.16 q2[3], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[2]
-; CHECK-NEXT:    vmov.16 q2[4], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[2]
-; CHECK-NEXT:    vmov.16 q2[5], r1
-; CHECK-NEXT:    vmov.u16 r1, q1[3]
-; CHECK-NEXT:    vmov.16 q2[6], r1
-; CHECK-NEXT:    vmov.u16 r1, q0[3]
-; CHECK-NEXT:    vmov.16 q2[7], r1
-; CHECK-NEXT:    vstrb.16 q2, [r0]
+; CHECK-NEXT:    vmovnt.i16 q1, q0
+; CHECK-NEXT:    vstrw.32 q1, [r0]
 ; CHECK-NEXT:    bx lr
 entry:
   %strided.vec = shufflevector <16 x i16> %src1, <16 x i16> undef, <16 x i32> <i32 8, i32 0, i32 9, i32 1, i32 10, i32 2, i32 11, i32 3, i32 12, i32 4, i32 13, i32 5, i32 14, i32 6, i32 15, i32 7>