Index: lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- lib/Transforms/Vectorize/LoopVectorize.cpp
+++ lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -3187,6 +3187,9 @@
       if (TruncatedTy == OriginalTy)
         continue;
 
+      if (!isa<Instruction>(I))
+        continue;
+
       IRBuilder<> B(cast<Instruction>(I));
       auto ShrinkOperand = [&](Value *V) -> Value* {
         if (auto *ZI = dyn_cast<ZExtInst>(V))
@@ -3242,6 +3245,17 @@
       } else if (isa<LoadInst>(I)) {
         // Don't do anything with the operands, just extend the result.
         continue;
+      } else if (auto *IE = dyn_cast<InsertElementInst>(I)) {
+        auto Elements = IE->getOperand(0)->getType()->getVectorNumElements();
+        auto *O0 = B.CreateZExtOrTrunc(
+            IE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
+        auto *O1 = B.CreateZExtOrTrunc(IE->getOperand(1), ScalarTruncatedTy);
+        NewI = B.CreateInsertElement(O0, O1, IE->getOperand(2));
+      } else if (auto *EE = dyn_cast<ExtractElementInst>(I)) {
+        auto Elements = EE->getOperand(0)->getType()->getVectorNumElements();
+        auto *O0 = B.CreateZExtOrTrunc(
+            EE->getOperand(0), VectorType::get(ScalarTruncatedTy, Elements));
+        NewI = B.CreateExtractElement(O0, EE->getOperand(2));
       } else {
         llvm_unreachable("Unhandled instruction type!");
       }
Index: test/Transforms/LoopVectorize/AArch64/type-shrinkage-insertelt.ll
===================================================================
--- /dev/null
+++ test/Transforms/LoopVectorize/AArch64/type-shrinkage-insertelt.ll
@@ -0,0 +1,47 @@
+; RUN: opt -S < %s -loop-vectorize -force-vector-width=4 | FileCheck %s
+
+target datalayout = "e-m:e-i64:64-i128:128-n32:64-S128"
+target triple = "aarch64--linux-gnu"
+
+; CHECK-LABEL: test0
+define void @test0(i16* noalias %M3) {
+entry:
+  br label %if.then1165.us
+
+if.then1165.us:                                   ; preds = %if.then1165.us, %entry
+  %indvars.iv1783 = phi i64 [ 0, %entry ], [ %indvars.iv.next1784, %if.then1165.us ]
+  %conv1177.us = zext i16 undef to i32
+  %add1178.us = add nsw i32 %conv1177.us, undef
+  %conv1179.us = trunc i32 %add1178.us to i16
+  %idxprom1181.us = ashr exact i64 undef, 32
+  %arrayidx1185.us = getelementptr inbounds i16, i16* %M3, i64 %idxprom1181.us
+  store i16 %conv1179.us, i16* %arrayidx1185.us, align 2
+  %indvars.iv.next1784 = add nuw nsw i64 %indvars.iv1783, 1
+  %exitcond1785 = icmp eq i64 %indvars.iv.next1784, 16
+  br i1 %exitcond1785, label %for.inc1286.loopexit, label %if.then1165.us
+
+for.inc1286.loopexit:                             ; preds = %if.then1165.us
+  ret void
+}
+
+; CHECK-LABEL: test1
+define void @test1(i16* noalias %M3) {
+entry:
+  br label %if.then1165.us
+
+if.then1165.us:                                   ; preds = %if.then1165.us, %entry
+  %indvars.iv1783 = phi i64 [ 0, %entry ], [ %indvars.iv.next1784, %if.then1165.us ]
+  %fptr = load i32, i32* undef, align 4
+  %conv1177.us = zext i16 undef to i32
+  %add1178.us = add nsw i32 %conv1177.us, %fptr
+  %conv1179.us = trunc i32 %add1178.us to i16
+  %idxprom1181.us = ashr exact i64 undef, 32
+  %arrayidx1185.us = getelementptr inbounds i16, i16* %M3, i64 %idxprom1181.us
+  store i16 %conv1179.us, i16* %arrayidx1185.us, align 2
+  %indvars.iv.next1784 = add nuw nsw i64 %indvars.iv1783, 1
+  %exitcond1785 = icmp eq i64 %indvars.iv.next1784, 16
+  br i1 %exitcond1785, label %for.inc1286.loopexit, label %if.then1165.us
+
+for.inc1286.loopexit:                             ; preds = %if.then1165.us
+  ret void
+}