diff --git a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
index 8dca8bf..4240f7f 100644
--- a/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
+++ b/llvm/lib/CodeGen/GlobalISel/LegalizerHelper.cpp
@@ -3807,7 +3807,11 @@
   // If the index is a constant, we can really break this down as you would
   // expect, and index into the target size pieces.
   int64_t IdxVal;
-  if (mi_match(Idx, MRI, m_ICst(IdxVal))) {
+  auto MaybeCst =
+      getConstantVRegValWithLookThrough(Idx, MRI, /*LookThroughInstrs*/ true,
+                                        /*HandleFConstants*/ false);
+  if (MaybeCst) {
+    IdxVal = MaybeCst->Value.getSExtValue();
     // Avoid out of bounds indexing the pieces.
     if (IdxVal >= VecTy.getNumElements()) {
       MIRBuilder.buildUndef(DstReg);
diff --git a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
index b54140e..f4058fc 100644
--- a/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
+++ b/llvm/lib/Target/AArch64/GISel/AArch64LegalizerInfo.cpp
@@ -639,7 +639,10 @@
             return Query.Types[1].getNumElements() <= 16;
           },
           0, s8)
-      .minScalarOrElt(0, s8); // Worst case, we need at least s8.
+      .minScalarOrElt(0, s8) // Worst case, we need at least s8.
+      .clampMaxNumElements(1, s64, 2)
+      .clampMaxNumElements(1, s32, 4)
+      .clampMaxNumElements(1, s16, 8);
 
   getActionDefinitionsBuilder(G_INSERT_VECTOR_ELT)
       .legalIf(typeInSet(0, {v8s16, v2s32, v4s32, v2s64}));