diff --git a/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerOptions.h b/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerOptions.h
--- a/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerOptions.h
+++ b/llvm/include/llvm/Transforms/Instrumentation/AddressSanitizerOptions.h
@@ -20,5 +20,16 @@
   Invalid, ///< Not a valid destructor Kind.
   // TODO(dliew): Add more more kinds.
 };
+
+/// Mode of ASan detect stack use after return
+enum class AsanDetectStackUseAfterReturnMode {
+  Never,   ///< Never detect stack use after return.
+  Runtime, ///< Detect stack use after return if runtime flag is enabled
+           ///< (ASAN_OPTIONS=detect_stack_use_after_return=1)
+  Always,  ///< Always detect stack use after return.
+  Invalid, ///< Not a valid detect mode.
+};
+
 } // namespace llvm
+
 #endif
diff --git a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
--- a/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
+++ b/llvm/lib/Transforms/Instrumentation/AddressSanitizer.cpp
@@ -72,6 +72,7 @@
 #include "llvm/Support/raw_ostream.h"
 #include "llvm/Transforms/Instrumentation.h"
 #include "llvm/Transforms/Instrumentation/AddressSanitizerCommon.h"
+#include "llvm/Transforms/Instrumentation/AddressSanitizerOptions.h"
 #include "llvm/Transforms/Utils/ASanStackFrameLayout.h"
 #include "llvm/Transforms/Utils/BasicBlockUtils.h"
 #include "llvm/Transforms/Utils/Local.h"
@@ -257,9 +258,23 @@
         "Inline shadow poisoning for blocks up to the given size in bytes."),
     cl::Hidden, cl::init(64));
 
-static cl::opt<bool> ClUseAfterReturn("asan-use-after-return",
-                                      cl::desc("Check stack-use-after-return"),
-                                      cl::Hidden, cl::init(true));
+static cl::opt<AsanDetectStackUseAfterReturnMode> ClUseAfterReturn(
+    "asan-use-after-return",
+    cl::desc("Sets the mode of detection for stack-use-after-return."),
+    cl::values(clEnumValN(AsanDetectStackUseAfterReturnMode::Never, "never",
+                          "Never detect stack use after return."),
+               clEnumValN(AsanDetectStackUseAfterReturnMode::Never,
+                          "0", // only needed to keep unit tests passing
+                          "Redundant with 'never'."),
+               clEnumValN(AsanDetectStackUseAfterReturnMode::Runtime, "runtime",
+                          "Detect stack use after return if "
+                          "binary flag 'asan-use-after-return' is true."),
+               clEnumValN(AsanDetectStackUseAfterReturnMode::Runtime,
+                          "1", // only needed to keep unit tests passing
+                          "redundant with 'runtime'."),
+               clEnumValN(AsanDetectStackUseAfterReturnMode::Always, "always",
+                          "Always detect stack use after return.")),
+    cl::Hidden, cl::init(AsanDetectStackUseAfterReturnMode::Runtime));
 
 static cl::opt<bool> ClRedzoneByvalArgs("asan-redzone-byval-args",
                                         cl::desc("Create redzones for byval "
@@ -3280,8 +3295,9 @@
   auto DescriptionString = ComputeASanStackFrameDescription(SVD);
   LLVM_DEBUG(dbgs() << DescriptionString << " --- " << L.FrameSize << "\n");
   uint64_t LocalStackSize = L.FrameSize;
-  bool DoStackMalloc = ClUseAfterReturn && !ASan.CompileKernel &&
-                       LocalStackSize <= kMaxStackMallocSize;
+  bool DoStackMalloc =
+      ClUseAfterReturn != AsanDetectStackUseAfterReturnMode::Never &&
+      !ASan.CompileKernel && LocalStackSize <= kMaxStackMallocSize;
   bool DoDynamicAlloca = ClDynamicAllocaStack;
   // Don't do dynamic alloca or stack malloc if:
   // 1) There is inline asm: too often it makes assumptions on which registers
@@ -3307,34 +3323,48 @@
     //     ? __asan_stack_malloc_N(LocalStackSize)
     //     : nullptr;
     // void *LocalStackBase = (FakeStack) ? FakeStack : alloca(LocalStackSize);
-    Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
-        kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
-    Value *UseAfterReturnIsEnabled = IRB.CreateICmpNE(
-        IRB.CreateLoad(IRB.getInt32Ty(), OptionDetectUseAfterReturn),
-        Constant::getNullValue(IRB.getInt32Ty()));
-    Instruction *Term =
-        SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
-    IRBuilder<> IRBIf(Term);
-    StackMallocIdx = StackMallocSizeClass(LocalStackSize);
-    assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
-    Value *FakeStackValue =
-        IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
-                         ConstantInt::get(IntptrTy, LocalStackSize));
-    IRB.SetInsertPoint(InsBefore);
-    FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
-                          ConstantInt::get(IntptrTy, 0));
-
-    Value *NoFakeStack =
-        IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
-    Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
-    IRBIf.SetInsertPoint(Term);
-    Value *AllocaValue =
-        DoDynamicAlloca ? createAllocaForLayout(IRBIf, L, true) : StaticAlloca;
-
-    IRB.SetInsertPoint(InsBefore);
-    LocalStackBase = createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
-    IRB.CreateStore(LocalStackBase, LocalStackBaseAlloca);
-    DIExprFlags |= DIExpression::DerefBefore;
+    if (ClUseAfterReturn == AsanDetectStackUseAfterReturnMode::Runtime) {
+      Constant *OptionDetectUseAfterReturn = F.getParent()->getOrInsertGlobal(
+          kAsanOptionDetectUseAfterReturn, IRB.getInt32Ty());
+      Value *UseAfterReturnIsEnabled = IRB.CreateICmpNE(
+          IRB.CreateLoad(IRB.getInt32Ty(), OptionDetectUseAfterReturn),
+          Constant::getNullValue(IRB.getInt32Ty()));
+      Instruction *Term =
+          SplitBlockAndInsertIfThen(UseAfterReturnIsEnabled, InsBefore, false);
+      IRBuilder<> IRBIf(Term);
+      StackMallocIdx = StackMallocSizeClass(LocalStackSize);
+      assert(StackMallocIdx <= kMaxAsanStackMallocSizeClass);
+      Value *FakeStackValue =
+          IRBIf.CreateCall(AsanStackMallocFunc[StackMallocIdx],
+                           ConstantInt::get(IntptrTy, LocalStackSize));
+      IRB.SetInsertPoint(InsBefore);
+      FakeStack = createPHI(IRB, UseAfterReturnIsEnabled, FakeStackValue, Term,
+                            ConstantInt::get(IntptrTy, 0));
+
+      Value *NoFakeStack =
+          IRB.CreateICmpEQ(FakeStack, Constant::getNullValue(IntptrTy));
+      Term = SplitBlockAndInsertIfThen(NoFakeStack, InsBefore, false);
+      IRBIf.SetInsertPoint(Term);
+      Value *AllocaValue = DoDynamicAlloca
+                               ? createAllocaForLayout(IRBIf, L, true)
+                               : StaticAlloca;
+
+      IRB.SetInsertPoint(InsBefore);
+      LocalStackBase =
+          createPHI(IRB, NoFakeStack, AllocaValue, Term, FakeStack);
+      IRB.CreateStore(LocalStackBase, LocalStackBaseAlloca);
+      DIExprFlags |= DIExpression::DerefBefore;
+    } else {
+      // assert(ClUseAfterReturn == AsanDetectStackUseAfterReturnMode:Always)
+      StackMallocIdx = StackMallocSizeClass(LocalStackSize);
+      FakeStack = IRB.CreateCall(AsanStackMallocFunc[StackMallocIdx],
+                                 ConstantInt::get(IntptrTy, LocalStackSize));
+      IRB.SetInsertPoint(InsBefore);
+
+      Value *AllocValue =
+          DoDynamicAlloca ? createAllocaForLayout(IRB, L, true) : StaticAlloca;
+      LocalStackBase = (FakeStack) ? FakeStack : AllocValue;
+    }
   } else {
     // void *FakeStack = nullptr;
     // void *LocalStackBase = alloca(LocalStackSize);
diff --git a/llvm/test/Instrumentation/AddressSanitizer/lifetime-uar-uas.ll b/llvm/test/Instrumentation/AddressSanitizer/lifetime-uar-uas.ll
--- a/llvm/test/Instrumentation/AddressSanitizer/lifetime-uar-uas.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/lifetime-uar-uas.ll
@@ -1,12 +1,16 @@
 ; Test handling of llvm.lifetime intrinsics in UAR/UAS modes.
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=0 -asan-use-after-scope=0 -S | FileCheck %s
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=0 -asan-use-after-scope=0 -S | FileCheck %s
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=1 -asan-use-after-scope=0 -S | FileCheck %s
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=1 -asan-use-after-scope=0 -S | FileCheck %s
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=0 -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=0 -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=1 -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=1 -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=never -asan-use-after-scope=0 -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=never -asan-use-after-scope=0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=runtime -asan-use-after-scope=0 -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=runtime -asan-use-after-scope=0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=always -asan-use-after-scope=0 -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=always -asan-use-after-scope=0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=never -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=never -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=runtime -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=runtime -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=always -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=always -asan-use-after-scope=1 -S | FileCheck %s --check-prefix=CHECK-UAS
 
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 
diff --git a/llvm/test/Instrumentation/AddressSanitizer/localescape.ll b/llvm/test/Instrumentation/AddressSanitizer/localescape.ll
--- a/llvm/test/Instrumentation/AddressSanitizer/localescape.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/localescape.ll
@@ -1,7 +1,15 @@
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return -asan-stack-dynamic-alloca -S | FileCheck %s
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return -asan-stack-dynamic-alloca -S | FileCheck %s
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=0 -asan-stack-dynamic-alloca=0 -S | FileCheck %s
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=0 -asan-stack-dynamic-alloca=0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=never -asan-stack-dynamic-alloca -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=never -asan-stack-dynamic-alloca -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=runtime -asan-stack-dynamic-alloca -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=runtime -asan-stack-dynamic-alloca -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=always -asan-stack-dynamic-alloca -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=always -asan-stack-dynamic-alloca -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=never -asan-stack-dynamic-alloca=0 -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=never -asan-stack-dynamic-alloca=0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=runtime -asan-stack-dynamic-alloca=0 -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=runtime -asan-stack-dynamic-alloca=0 -S | FileCheck %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=always -asan-stack-dynamic-alloca=0 -S | FileCheck %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=always -asan-stack-dynamic-alloca=0 -S | FileCheck %s
 
 target datalayout = "e-m:x-p:32:32-i64:64-f80:32-n8:16:32-a:0:32-S32"
 target triple = "i686-pc-windows-msvc18.0.0"
diff --git a/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll b/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll
--- a/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/stack-poisoning.ll
@@ -1,7 +1,9 @@
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return -S | FileCheck --check-prefix=CHECK-UAR %s
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return -S | FileCheck --check-prefix=CHECK-UAR %s
-; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=0 -S | FileCheck --check-prefix=CHECK-PLAIN %s
-; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=0 -S | FileCheck --check-prefix=CHECK-PLAIN %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=never -S | FileCheck --check-prefix=CHECK-PLAIN %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=never -S | FileCheck --check-prefix=CHECK-PLAIN %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=runtime -S | FileCheck --check-prefixes=CHECK-UAR,CHECK-UAR-RUNTIME %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=runtime -S | FileCheck --check-prefixes=CHECK-UAR,CHECK-UAR-RUNTIME %s
+; RUN: opt < %s -asan -asan-module -enable-new-pm=0 -asan-use-after-return=always -S | FileCheck --check-prefixes=CHECK-UAR,CHECK-UAR-NORUNTIME %s
+; RUN: opt < %s -passes='asan-pipeline' -asan-use-after-return=always -S | FileCheck --check-prefix=CHECK-UAR %s
 target datalayout = "e-i64:64-f80:128-s:64-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
@@ -14,10 +16,12 @@
 ; CHECK-PLAIN: ret void
 
 ; CHECK-UAR-LABEL: Bar
-; CHECK-UAR: load i32, i32* @__asan_option_detect_stack_use_after_return
-; CHECK-UAR: label
+; CHECK-UAR-RUNTIME: load i32, i32* @__asan_option_detect_stack_use_after_return
+; CHECK-UAR-RUNTIME: label
+; CHECK-UAR-NORUNTIME-NOT: load i32, i32* @__asan_option_detect_stack_use_after_return
+; CHECK-UAR-NORUNTIME-NOT: label
 ; CHECK-UAR: call i64 @__asan_stack_malloc_4
-; CHECK-UAR: label
+; CHECK-UAR-RUNTIME: label
 ; Poison red zones.
 ; CHECK-UAR: store i64 -1007680412564983311
 ; CHECK-UAR: store i64 72057598113936114
diff --git a/llvm/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll b/llvm/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll
--- a/llvm/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll
+++ b/llvm/test/Instrumentation/AddressSanitizer/stack_dynamic_alloca.ll
@@ -1,11 +1,15 @@
 ; RUN: opt < %s -asan -asan-module -asan-stack-dynamic-alloca \
-; RUN:       -asan-use-after-return -S -enable-new-pm=0 | FileCheck %s
+; RUN:       -asan-use-after-return=runtime -S -enable-new-pm=0 | FileCheck %s --check-prefixes=CHECK-RUNTIME
 ; RUN: opt < %s -passes='asan-pipeline' -asan-stack-dynamic-alloca \
-; RUN:       -asan-use-after-return -S | FileCheck %s
+; RUN:       -asan-use-after-return=runtime -S | FileCheck %s --check-prefixes=CHECK-RUNTIME
 ; RUN: opt < %s -asan -asan-module -asan-stack-dynamic-alloca -asan-mapping-scale=5 \
-; RUN:       -asan-use-after-return -S -enable-new-pm=0 | FileCheck %s
-; RUN: opt < %s -passes='asan-pipeline' -asan-stack-dynamic-alloca -asan-mapping-scale=5 \
-; RUN:       -asan-use-after-return -S | FileCheck %s
+; RUN:       -asan-use-after-return=runtime -S -enable-new-pm=0 | FileCheck %s --check-prefixes=CHECK-RUNTIME
+; RUN: opt < %s -asan -asan-module -asan-stack-dynamic-alloca \
+; RUN:       -asan-use-after-return=always -S -enable-new-pm=0 | FileCheck %s --check-prefixes=CHECK-NORUNTIME
+; RUN: opt < %s -passes='asan-pipeline' -asan-stack-dynamic-alloca \
+; RUN:       -asan-use-after-return=always -S | FileCheck %s --check-prefixes=CHECK-NORUNTIME
+; RUN: opt < %s -asan -asan-module -asan-stack-dynamic-alloca -asan-mapping-scale=5 \
+; RUN:       -asan-use-after-return=always -S -enable-new-pm=0 | FileCheck %s --check-prefixes=CHECK-NORUNTIME
 target datalayout = "e-p:64:64:64-i1:8:8-i8:8:8-i16:16:16-i32:32:32-i64:64:64-f32:32:32-f64:64:64-v64:64:64-v128:128:128-a0:0:64-s0:64:64-f80:128:128-n8:16:32:64-S128"
 target triple = "x86_64-unknown-linux-gnu"
 
@@ -14,7 +18,8 @@
 ; CHECK-LABEL: Func1
 
 ; CHECK: entry:
-; CHECK: load i32, i32* @__asan_option_detect_stack_use_after_return
+; CHECK-RUNTIME: load i32, i32* @__asan_option_detect_stack_use_after_return
+; CHECK-NORUNTIME-NOT: load i32, i32* @__asan_option_detect_stack_use_after_return
 
 ; CHECK: [[UAR_ENABLED_BB:^[0-9]+]]:
 ; CHECK: [[FAKE_STACK_RT:%[0-9]+]] = call i64 @__asan_stack_malloc_