Index: lib/CodeGen/BackendUtil.cpp
===================================================================
--- lib/CodeGen/BackendUtil.cpp
+++ lib/CodeGen/BackendUtil.cpp
@@ -562,7 +562,7 @@
     addCoroutinePassesToExtensionPoints(PMBuilder);
 
   if (LangOpts.Sanitize.has(SanitizerKind::LocalBounds)) {
-    PMBuilder.addExtension(PassManagerBuilder::EP_ScalarOptimizerLate,
+    PMBuilder.addExtension(PassManagerBuilder::EP_EarlyAsPossible,
                            addBoundsCheckingPass);
     PMBuilder.addExtension(PassManagerBuilder::EP_EnabledOnOptLevel0,
                            addBoundsCheckingPass);
Index: test/CodeGen/bounds-checking-opt.c
===================================================================
--- /dev/null
+++ test/CodeGen/bounds-checking-opt.c
@@ -0,0 +1,20 @@
+// RUN: %clang -S -fsanitize=local-bounds -emit-llvm -target x86_64-- %s -o - | FileCheck -check-prefix=O0 %s
+// RUN: %clang -S -fsanitize=local-bounds -emit-llvm -target x86_64-- -O2 %s -o - | FileCheck -check-prefix=O2 %s
+// RUN: %clang -S -fsanitize=local-bounds -emit-llvm -target aarch64-- %s -o - | FileCheck -check-prefix=O0 %s
+// RUN: %clang -S -fsanitize=local-bounds -emit-llvm -target aarch64-- -O2 %s -o - | FileCheck -check-prefix=O2 %s
+
+extern void fill(int *arr);
+
+// CHECK-LABEL: @f
+int f(int x) {
+  // O0: call {{.*}} @llvm.trap
+  // O2-NOT: call {{.*}} @llvm.trap
+  int foo[1000];
+  fill(foo);
+  int sum = 0;
+  #pragma clang loop vectorize(disable)
+  #pragma clang loop unroll(disable)
+  for (unsigned i = 0; i < 1000; i++)
+    sum += foo[i];
+  return sum;
+}