diff --git a/llvm/lib/IR/ConstantFold.cpp b/llvm/lib/IR/ConstantFold.cpp
--- a/llvm/lib/IR/ConstantFold.cpp
+++ b/llvm/lib/IR/ConstantFold.cpp
@@ -686,6 +686,10 @@
   ConstantInt *CIdx = dyn_cast<ConstantInt>(Idx);
   if (!CIdx) return nullptr;
 
+  // Inserting null into all zeros is still all zeros.
+  if (isa<ConstantAggregateZero>(Val) && Elt->isNullValue())
+    return Val;
+
   // Do not iterate on scalable vector. The num of elements is unknown at
   // compile-time.
   if (isa<ScalableVectorType>(Val->getType()))
diff --git a/llvm/test/Transforms/LoopVectorize/AArch64/sve-widen-phi.ll b/llvm/test/Transforms/LoopVectorize/AArch64/sve-widen-phi.ll
--- a/llvm/test/Transforms/LoopVectorize/AArch64/sve-widen-phi.ll
+++ b/llvm/test/Transforms/LoopVectorize/AArch64/sve-widen-phi.ll
@@ -251,7 +251,7 @@
 ; CHECK:       vector.body:
 ; CHECK-NEXT:    [[POINTER_PHI:%.*]] = phi i32* [ [[A]], [[VECTOR_PH]] ], [ [[PTR_IND:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[INDEX:%.*]] = phi i64 [ 0, [[VECTOR_PH]] ], [ [[INDEX_NEXT:%.*]], [[VECTOR_BODY]] ]
-; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <vscale x 2 x i32> [ insertelement (<vscale x 2 x i32> zeroinitializer, i32 0, i32 0), [[VECTOR_PH]] ], [ [[TMP9:%.*]], [[VECTOR_BODY]] ]
+; CHECK-NEXT:    [[VEC_PHI:%.*]] = phi <vscale x 2 x i32> [ zeroinitializer, [[VECTOR_PH]] ], [ [[TMP9:%.*]], [[VECTOR_BODY]] ]
 ; CHECK-NEXT:    [[TMP4:%.*]] = call i64 @llvm.vscale.i64()
 ; CHECK-NEXT:    [[TMP5:%.*]] = shl nuw nsw i64 [[TMP4]], 1
 ; CHECK-NEXT:    [[TMP6:%.*]] = call <vscale x 2 x i64> @llvm.experimental.stepvector.nxv2i64()