Index: llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
===================================================================
--- llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
+++ llvm/lib/Transforms/Vectorize/LoopVectorize.cpp
@@ -7405,6 +7405,19 @@
   return true;
 }
 
+static bool hasRuntimeChecksAndOptSize(Function *F,
+                                        LoopVectorizationLegality &LVL) {
+  const LoopAccessInfo *LAI = LVL.getLAI();
+  if (!LAI)
+    return false;
+
+  bool Empty = LAI->getRuntimePointerChecking()->getChecks().empty();
+  if (!Empty && F->hasOptSize())
+    return true;
+
+  return false;
+}
+
 bool LoopVectorizePass::processLoop(Loop *L) {
   assert((EnableVPlanNativePath || L->empty()) &&
          "VPlan-native path is not enabled. Only process inner loops.");
@@ -7458,6 +7471,12 @@
     return false;
   }
 
+  if (hasRuntimeChecksAndOptSize(F, LVL)) {
+    LLVM_DEBUG(dbgs() << "LV: Not vectorizing: runtime checks required, but "
+                         "optimizing for code size.\n");
+    return false;
+  }
+
   // Check the function attributes and profiles to find out if this function
   // should be optimized for size.
   ScalarEpilogueLowering SEL = getScalarEpilogueLowering(F, L, Hints, PSI, BFI);
Index: llvm/test/Transforms/LoopVectorize/runtime-check-optsize.ll
===================================================================
--- /dev/null
+++ llvm/test/Transforms/LoopVectorize/runtime-check-optsize.ll
@@ -0,0 +1,67 @@
+; RUN: opt < %s -O1 -disable-basicaa -S -o - | FileCheck %s
+
+; This function has the OptSize attribute, and requires runtime memory checks.
+; Check that we nicely bail, i.e. don't vectorise this loop (and
+; don't run in an assert) because we don't want to grow code-size.
+
+target datalayout = "e-m:e-p270:32:32-p271:32:32-p272:64:64-i64:64-f80:128-n8:16:32:64-S128"
+target triple = "x86_64-unknown-linux-gnu"
+
+define dso_local void @f_w2(i64* noalias %x_p, i64* noalias %y_p, i64* noalias %z_p) #0 {
+; CHECK-LABEL: @f_w2(
+; CHECK-NOT:   vector.body:
+entry:
+  %x_p.addr = alloca i64*, align 8
+  %y_p.addr = alloca i64*, align 8
+  %z_p.addr = alloca i64*, align 8
+  %i = alloca i32, align 4
+  store i64* %x_p, i64** %x_p.addr, align 8
+  store i64* %y_p, i64** %y_p.addr, align 8
+  store i64* %z_p, i64** %z_p.addr, align 8
+  %0 = bitcast i32* %i to i8*
+  store i32 0, i32* %i, align 4
+  br label %for.cond
+
+for.cond:
+  %1 = load i32, i32* %i, align 4
+  %cmp = icmp slt i32 %1, 128
+  br i1 %cmp, label %for.body, label %for.cond.cleanup
+
+for.cond.cleanup:
+  %2 = bitcast i32* %i to i8*
+  br label %for.end
+
+for.body:
+  %3 = load i64*, i64** %x_p.addr, align 8
+  %4 = load i32, i32* %i, align 4
+  %idxprom = sext i32 %4 to i64
+  %arrayidx = getelementptr inbounds i64, i64* %3, i64 %idxprom
+  %5 = load i64, i64* %arrayidx, align 8
+  %6 = load i64*, i64** %y_p.addr, align 8
+  %7 = load i32, i32* %i, align 4
+  %idxprom1 = sext i32 %7 to i64
+  %arrayidx2 = getelementptr inbounds i64, i64* %6, i64 %idxprom1
+  %8 = load i64, i64* %arrayidx2, align 8
+  %add = add nsw i64 %5, %8
+  %9 = load i64*, i64** %z_p.addr, align 8
+  %10 = load i32, i32* %i, align 4
+  %idxprom3 = sext i32 %10 to i64
+  %arrayidx4 = getelementptr inbounds i64, i64* %9, i64 %idxprom3
+  store i64 %add, i64* %arrayidx4, align 8
+  br label %for.inc
+
+for.inc:
+  %11 = load i32, i32* %i, align 4
+  %inc = add nsw i32 %11, 1
+  store i32 %inc, i32* %i, align 4
+  br label %for.cond, !llvm.loop !10
+
+for.end:
+  ret void
+}
+
+attributes #0 = { nounwind optsize uwtable "target-cpu"="core-avx2" "target-features"="+avx,+avx2" }
+
+!10 = distinct !{!10, !11, !12}
+!11 = !{!"llvm.loop.vectorize.width", i32 2}
+!12 = !{!"llvm.loop.vectorize.enable", i1 true}