diff --git a/llvm/lib/Target/AArch64/AArch64StackTagging.cpp b/llvm/lib/Target/AArch64/AArch64StackTagging.cpp
--- a/llvm/lib/Target/AArch64/AArch64StackTagging.cpp
+++ b/llvm/lib/Target/AArch64/AArch64StackTagging.cpp
@@ -73,6 +73,10 @@
 static cl::opt<unsigned> ClScanLimit("stack-tagging-merge-init-scan-limit",
                                      cl::init(40), cl::Hidden);
 
+static cl::opt<unsigned>
+    ClMergeInitSizeLimit("stack-tagging-merge-init-size-limit", cl::init(272),
+                         cl::Hidden);
+
 static const Align kTagGranuleSize = Align(16);
 
 namespace {
@@ -434,7 +438,8 @@
   bool LittleEndian =
       Triple(AI->getModule()->getTargetTriple()).isLittleEndian();
   // Current implementation of initializer merging assumes little endianness.
-  if (MergeInit && !F->hasOptNone() && LittleEndian) {
+  if (MergeInit && !F->hasOptNone() && LittleEndian &&
+      Size < ClMergeInitSizeLimit) {
     LLVM_DEBUG(dbgs() << "collecting initializers for " << *AI
                       << ", size = " << Size << "\n");
     InsertBefore = collectInitializers(InsertBefore, Ptr, Size, IB);
diff --git a/llvm/test/CodeGen/AArch64/stack-tagging-initializer-merge.ll b/llvm/test/CodeGen/AArch64/stack-tagging-initializer-merge.ll
--- a/llvm/test/CodeGen/AArch64/stack-tagging-initializer-merge.ll
+++ b/llvm/test/CodeGen/AArch64/stack-tagging-initializer-merge.ll
@@ -306,3 +306,17 @@
 ; CHECK:  call void @llvm.aarch64.stgp(i8* {{.*}}, i64 46360584388608, i64 0)
 ; CHECK:  call void @llvm.aarch64.stgp(i8* {{.*}}, i64 0, i64 3038287259199220266)
 ; CHECK:  ret void
+
+define void @LargeAlloca() sanitize_memtag {
+entry:
+  %x = alloca i32, i32 256, align 16
+  %0 = bitcast i32* %x to i8*
+  call void @llvm.memset.p0i8.i64(i8* nonnull align 16 %0, i8 42, i64 256, i1 false)
+  call void @use(i8* nonnull %0)
+  ret void
+}
+
+; CHECK-LABEL: define void @LargeAlloca(
+; CHECK:  call void @llvm.aarch64.settag(i8* {{.*}}, i64 1024)
+; CHECK:  call void @llvm.memset.p0i8.i64(i8* {{.*}}, i8 42, i64 256,
+; CHECK:  ret void