diff --git a/clang/lib/CodeGen/BackendUtil.cpp b/clang/lib/CodeGen/BackendUtil.cpp
--- a/clang/lib/CodeGen/BackendUtil.cpp
+++ b/clang/lib/CodeGen/BackendUtil.cpp
@@ -353,7 +353,8 @@
 
 static void addMemTagOptimizationPasses(const PassManagerBuilder &Builder,
                                         legacy::PassManagerBase &PM) {
-  PM.add(createStackSafetyGlobalInfoWrapperPass(/*SetMetadata=*/true));
+  PM.add(createStackSafetyGlobalInfoWrapperPass(/*SetMetadata=*/true,
+                                                /*Optional=*/true));
 }
 
 static TargetLibraryInfoImpl *createTLII(llvm::Triple &TargetTriple,
@@ -1346,7 +1347,7 @@
 
     if (CodeGenOpts.OptimizationLevel > 0 &&
         LangOpts.Sanitize.has(SanitizerKind::MemTag)) {
-      MPM.addPass(StackSafetyGlobalAnnotatorPass());
+      MPM.addPass(StackSafetyGlobalAnnotatorPass(/*Optional=*/true));
     }
 
     if (CodeGenOpts.OptimizationLevel == 0) {
diff --git a/clang/lib/CodeGen/CodeGenModule.cpp b/clang/lib/CodeGen/CodeGenModule.cpp
--- a/clang/lib/CodeGen/CodeGenModule.cpp
+++ b/clang/lib/CodeGen/CodeGenModule.cpp
@@ -574,6 +574,12 @@
                               CodeGenOpts.SanitizeCfiCanonicalJumpTables);
   }
 
+  if (CodeGenOpts.OptimizationLevel > 0 &&
+      LangOpts.Sanitize.has(SanitizerKind::MemTag)) {
+    // Indicate that we want to StackSafety metadata.
+    getModule().addModuleFlag(llvm::Module::Override, "stack-safe", 1);
+  }
+
   if (CodeGenOpts.CFProtectionReturn &&
       Target.checkCFProtectionReturnSupported(getDiags())) {
     // Indicate that we want to instrument return control flow protection.
diff --git a/clang/test/CodeGen/stack-safe-flag.cpp b/clang/test/CodeGen/stack-safe-flag.cpp
new file mode 100644
--- /dev/null
+++ b/clang/test/CodeGen/stack-safe-flag.cpp
@@ -0,0 +1,6 @@
+// RUN: %clang_cc1 -O0 -triple aarch64-unknown-linux -fsanitize=memtag -emit-llvm -o - %s | FileCheck %s -check-prefix=NO
+// RUN: %clang_cc1 -O1 -triple aarch64-unknown-linux -emit-llvm -o - %s                   | FileCheck %s -check-prefix=NO
+// RUN: %clang_cc1 -O1 -triple aarch64-unknown-linux -fsanitize=memtag -emit-llvm -o - %s | FileCheck %s
+
+// NO-NOT: "stack-safe"
+// CHECK: !{i32 4, !"stack-safe", i32 1}
\ No newline at end of file
diff --git a/clang/test/Driver/memtag_lto.c b/clang/test/Driver/memtag_lto.c
--- a/clang/test/Driver/memtag_lto.c
+++ b/clang/test/Driver/memtag_lto.c
@@ -75,8 +75,7 @@
 // RUN:  -r %t.lto1.bc,w, \
 // RUN:  -r %t.lto2.bc,use,plx \
 // RUN:  -r %t.lto2.bc,z,
-// FIXME: Must be -check-prefixes=XSAFE,YSAFE
-// RUN: llvm-dis %t.lto.0.5.precodegen.bc -o - | FileCheck %s -check-prefixes=XUNSAFE,YSAFE
+// RUN: llvm-dis %t.lto.0.5.precodegen.bc -o - | FileCheck %s -check-prefixes=XSAFE,YSAFE
 
 // Full LTO, new PM: both are safe.
 // RUN: %clang -fexperimental-new-pass-manager -O1 -target aarch64-unknown-linux -march=armv8+memtag -fsanitize=memtag -c %s -flto=full -o %t.ltonewpm1.bc
@@ -88,8 +87,7 @@
 // RUN:  -r %t.ltonewpm1.bc,w, \
 // RUN:  -r %t.ltonewpm2.bc,use,plx \
 // RUN:  -r %t.ltonewpm2.bc,z,
-// FIXME: Must be -check-prefixes=XSAFE,YSAFE
-// RUN: llvm-dis %t.ltonewpm.0.5.precodegen.bc -o - | FileCheck %s -check-prefixes=XUNSAFE,YSAFE
+// RUN: llvm-dis %t.ltonewpm.0.5.precodegen.bc -o - | FileCheck %s -check-prefixes=XSAFE,YSAFE
 
 // Thin LTO: both are safe.
 // RUN: %clang -fno-experimental-new-pass-manager -O1 -target aarch64-unknown-linux -march=armv8+memtag -fsanitize=memtag -c %s -flto=thin -o %t.thinlto1.bc
diff --git a/llvm/include/llvm/Analysis/StackSafetyAnalysis.h b/llvm/include/llvm/Analysis/StackSafetyAnalysis.h
--- a/llvm/include/llvm/Analysis/StackSafetyAnalysis.h
+++ b/llvm/include/llvm/Analysis/StackSafetyAnalysis.h
@@ -98,11 +98,16 @@
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
 };
 
+// Attaches StackSafety metadata to allocas.
 class StackSafetyGlobalAnnotatorPass
     : public PassInfoMixin<StackSafetyGlobalAnnotatorPass> {
 
+  bool Optional = false;
+
 public:
-  explicit StackSafetyGlobalAnnotatorPass() {}
+  // When Optional is true the pass does nothing if no consumers of meta
+  // information is expected.
+  explicit StackSafetyGlobalAnnotatorPass(bool Optional) : Optional(Optional) {}
   PreservedAnalyses run(Module &M, ModuleAnalysisManager &AM);
 };
 
@@ -110,12 +115,14 @@
 /// (legacy pass manager).
 class StackSafetyGlobalInfoWrapperPass : public ModulePass {
   StackSafetyGlobalInfo SSGI;
-  bool SetMetadata;
+  bool SetMetadata = false;
+  bool Optional = false;
 
 public:
   static char ID;
 
-  StackSafetyGlobalInfoWrapperPass(bool SetMetadata = false);
+  explicit StackSafetyGlobalInfoWrapperPass(bool SetMetadata = false,
+                                            bool Optional = false);
 
   const StackSafetyGlobalInfo &getResult() const { return SSGI; }
 
@@ -125,7 +132,11 @@
   bool runOnModule(Module &M) override;
 };
 
-ModulePass *createStackSafetyGlobalInfoWrapperPass(bool SetMetadata);
+// Attaches StackSafety metadata to allocas.
+// When Optional is true the pass does nothing if no consumers of meta
+// information is expected.
+ModulePass *createStackSafetyGlobalInfoWrapperPass(bool SetMetadata,
+                                                   bool Optional);
 
 } // end namespace llvm
 
diff --git a/llvm/lib/Analysis/StackSafetyAnalysis.cpp b/llvm/lib/Analysis/StackSafetyAnalysis.cpp
--- a/llvm/lib/Analysis/StackSafetyAnalysis.cpp
+++ b/llvm/lib/Analysis/StackSafetyAnalysis.cpp
@@ -603,6 +603,12 @@
   return Changed;
 }
 
+bool isMetadataNeeded(const Module &M) {
+  auto *CI =
+      mdconst::extract_or_null<ConstantInt>(M.getModuleFlag("stack-safe"));
+  return CI && CI->getZExtValue();
+}
+
 } // end anonymous namespace
 
 StackSafetyInfo::StackSafetyInfo() = default;
@@ -676,6 +682,8 @@
 
 PreservedAnalyses
 StackSafetyGlobalAnnotatorPass::run(Module &M, ModuleAnalysisManager &AM) {
+  if (Optional && !isMetadataNeeded(M))
+    return PreservedAnalyses::all();
   auto &SSGI = AM.getResult<StackSafetyGlobalAnalysis>(M);
   (void)setStackSafetyMetadata(M, SSGI);
   return PreservedAnalyses::all();
@@ -684,8 +692,8 @@
 char StackSafetyGlobalInfoWrapperPass::ID = 0;
 
 StackSafetyGlobalInfoWrapperPass::StackSafetyGlobalInfoWrapperPass(
-    bool SetMetadata)
-    : ModulePass(ID), SetMetadata(SetMetadata) {
+    bool SetMetadata, bool Optional)
+    : ModulePass(ID), SetMetadata(SetMetadata), Optional(Optional) {
   initializeStackSafetyGlobalInfoWrapperPassPass(
       *PassRegistry::getPassRegistry());
 }
@@ -701,6 +709,9 @@
 }
 
 bool StackSafetyGlobalInfoWrapperPass::runOnModule(Module &M) {
+  if (Optional && !isMetadataNeeded(M))
+    return false;
+
   StackSafetyDataFlowAnalysis SSDFA(
       M, [this](Function &F) -> const StackSafetyInfo & {
         return getAnalysis<StackSafetyInfoWrapperPass>(F).getResult();
@@ -709,8 +720,9 @@
   return SetMetadata ? setStackSafetyMetadata(M, SSGI) : false;
 }
 
-ModulePass *llvm::createStackSafetyGlobalInfoWrapperPass(bool SetMetadata) {
-  return new StackSafetyGlobalInfoWrapperPass(SetMetadata);
+ModulePass *llvm::createStackSafetyGlobalInfoWrapperPass(bool SetMetadata,
+                                                         bool Optional) {
+  return new StackSafetyGlobalInfoWrapperPass(SetMetadata, Optional);
 }
 
 static const char LocalPassArg[] = "stack-safety-local";
diff --git a/llvm/lib/Passes/PassBuilder.cpp b/llvm/lib/Passes/PassBuilder.cpp
--- a/llvm/lib/Passes/PassBuilder.cpp
+++ b/llvm/lib/Passes/PassBuilder.cpp
@@ -1288,6 +1288,9 @@
   // is fixed.
   MPM.addPass(WholeProgramDevirtPass(ExportSummary, nullptr));
 
+  // Add stack safety metatada if needed.
+  MPM.addPass(StackSafetyGlobalAnnotatorPass(true));
+
   // Stop here at -O1.
   if (Level == OptimizationLevel::O1) {
     // The LowerTypeTestsPass needs to run to lower type metadata and the
diff --git a/llvm/lib/Passes/PassRegistry.def b/llvm/lib/Passes/PassRegistry.def
--- a/llvm/lib/Passes/PassRegistry.def
+++ b/llvm/lib/Passes/PassRegistry.def
@@ -96,7 +96,7 @@
 MODULE_PASS("kasan-module", ModuleAddressSanitizerPass(/*CompileKernel=*/true, false, true, false))
 MODULE_PASS("sancov-module", ModuleSanitizerCoveragePass())
 MODULE_PASS("poison-checking", PoisonCheckingPass())
-MODULE_PASS("stack-safety-annotator", StackSafetyGlobalAnnotatorPass())
+MODULE_PASS("stack-safety-annotator", StackSafetyGlobalAnnotatorPass(/*Optional=*/false))
 #undef MODULE_PASS
 
 #ifndef CGSCC_ANALYSIS
diff --git a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
--- a/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
+++ b/llvm/lib/Transforms/IPO/PassManagerBuilder.cpp
@@ -22,6 +22,7 @@
 #include "llvm/Analysis/InlineCost.h"
 #include "llvm/Analysis/Passes.h"
 #include "llvm/Analysis/ScopedNoAliasAA.h"
+#include "llvm/Analysis/StackSafetyAnalysis.h"
 #include "llvm/Analysis/TargetLibraryInfo.h"
 #include "llvm/Analysis/TypeBasedAliasAnalysis.h"
 #include "llvm/IR/DataLayout.h"
@@ -916,6 +917,10 @@
   // Apply whole-program devirtualization and virtual constant propagation.
   PM.add(createWholeProgramDevirtPass(ExportSummary, nullptr));
 
+  // Add stack safety metatada if needed.
+  PM.add(createStackSafetyGlobalInfoWrapperPass(
+      /*SetMetadata=*/true, /*Optional=*/true));
+
   // That's all we need at opt level 1.
   if (OptLevel == 1)
     return;
diff --git a/llvm/test/Other/new-pm-lto-defaults.ll b/llvm/test/Other/new-pm-lto-defaults.ll
--- a/llvm/test/Other/new-pm-lto-defaults.ll
+++ b/llvm/test/Other/new-pm-lto-defaults.ll
@@ -61,6 +61,7 @@
 ; CHECK-O-NEXT: Running analysis: CallGraphAnalysis
 ; CHECK-O-NEXT: Running pass: GlobalSplitPass
 ; CHECK-O-NEXT: Running pass: WholeProgramDevirtPass
+; CHECK-O-NEXT: Running pass: StackSafetyGlobalAnnotatorPass
 ; CHECK-O1-NEXT: Running pass: LowerTypeTestsPass
 ; CHECK-O2-NEXT: Running pass: GlobalOptPass
 ; CHECK-O2-NEXT: Running pass: ModuleToFunctionPassAdaptor<{{.*}}PromotePass>