diff --git a/clang/lib/Basic/Targets/ARM.cpp b/clang/lib/Basic/Targets/ARM.cpp
--- a/clang/lib/Basic/Targets/ARM.cpp
+++ b/clang/lib/Basic/Targets/ARM.cpp
@@ -896,6 +896,16 @@
     Builder.defineMacro("__ARM_BF16_FORMAT_ALTERNATIVE", "1");
   }
 
+  if (Opts.BranchTargetEnforcement)
+    Builder.defineMacro("__ARM_FEATURE_BTI_DEFAULT", "1");
+
+  if (Opts.hasSignReturnAddress()) {
+    unsigned Value = Opts.isSignReturnAddressWithAKey() ? 1 : 2;
+    if (Opts.isSignReturnAddressScopeAll())
+      Value |= 1 << 2;
+    Builder.defineMacro("__ARM_FEATURE_PAC_DEFAULT", Twine(Value));
+  }
+
   switch (ArchKind) {
   default:
     break;
diff --git a/clang/test/Preprocessor/arm-target-features.c b/clang/test/Preprocessor/arm-target-features.c
--- a/clang/test/Preprocessor/arm-target-features.c
+++ b/clang/test/Preprocessor/arm-target-features.c
@@ -877,6 +877,25 @@
 // RUN: %clang -target arm-none-none-eabi -march=armv7-m -mfpu=softvfp -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-SOFTVFP %s
 // CHECK-SOFTVFP-NOT: #define __ARM_FP 0x
 
+// Test Armv8.1-M PACBTI
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-NOBTI,CHECK-NOPAC %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=bti -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-BTI,CHECK-NOPAC %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=pac-ret -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC,CHECK-NOBTI %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=pac-ret+b-key -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC-BKEY,CHECK-NOBTI %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=pac-ret+leaf -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC-LEAF,CHECK-NOBTI %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=pac-ret+b-key+leaf -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC-BKEY-LEAF,CHECK-NOBTI %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=bti+pac-ret -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC,CHECK-BTI %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=bti+pac-ret+b-key -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC-BKEY,CHECK-BTI %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=bti+pac-ret+leaf -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC-LEAF,CHECK-BTI %s
+// RUN: %clang -target arm-arm-none-eabi -march=armv8.1-m.main -mbranch-protection=bti+pac-ret+b-key+leaf -x c -E -dM %s -o - | FileCheck --check-prefixes=CHECK-PAC-BKEY-LEAF,CHECK-BTI %s
+// CHECK-NOBTI-NOT: #define __ARM_FEATURE_BTI_DEFAULT
+// CHECK-NOPAC-NOT: #define __ARM_FEATURE_PAC_DEFAULT
+// CHECK-BTI: #define __ARM_FEATURE_BTI_DEFAULT 1
+// CHECK-PAC: #define __ARM_FEATURE_PAC_DEFAULT 1
+// CHECK-PAC-BKEY: #define __ARM_FEATURE_PAC_DEFAULT 2
+// CHECK-PAC-LEAF: #define __ARM_FEATURE_PAC_DEFAULT 5
+// CHECK-PAC-BKEY-LEAF: #define __ARM_FEATURE_PAC_DEFAULT 6
+
 // ================== Check BFloat16 Extensions.
 // RUN: %clang -target arm-arm-none-eabi -march=armv8.6-a+bf16 -x c -E -dM %s -o - 2>&1 | FileCheck -check-prefix=CHECK-BFLOAT %s
 // CHECK-BFLOAT: #define __ARM_BF16_FORMAT_ALTERNATIVE 1