diff --git a/clang/include/clang/Basic/LangOptions.h b/clang/include/clang/Basic/LangOptions.h
--- a/clang/include/clang/Basic/LangOptions.h
+++ b/clang/include/clang/Basic/LangOptions.h
@@ -367,6 +367,21 @@
 
   /// Return the OpenCL C or C++ version as a VersionTuple.
   VersionTuple getOpenCLVersionTuple() const;
+
+  /// Check if return address signing is enabled.
+  bool hasSignReturnAddress() const {
+    return getSignReturnAddressScope() != SignReturnAddressScopeKind::None;
+  }
+
+  /// Check if return address signing uses AKey.
+  bool isSignReturnAddressWithAKey() const {
+    return getSignReturnAddressKey() == SignReturnAddressKeyKind::AKey;
+  }
+
+  /// Check if leaf functions are also signed.
+  bool isSignReturnAddressScopeAll() const {
+    return getSignReturnAddressScope() == SignReturnAddressScopeKind::All;
+  }
 };
 
 /// Floating point control options
diff --git a/clang/lib/Basic/Targets/AArch64.cpp b/clang/lib/Basic/Targets/AArch64.cpp
--- a/clang/lib/Basic/Targets/AArch64.cpp
+++ b/clang/lib/Basic/Targets/AArch64.cpp
@@ -283,6 +283,27 @@
   if ((FPU & NeonMode) && HasFP16FML)
     Builder.defineMacro("__ARM_FEATURE_FP16FML", "1");
 
+  if (Opts.hasSignReturnAddress()) {
+    // Bitmask:
+    // 0: Protection using the A key
+    // 1: Protection using the B key
+    // 2: Protection including leaf functions
+    unsigned Value = 0;
+
+    if (Opts.isSignReturnAddressWithAKey())
+      Value |= (1 << 0);
+    else
+      Value |= (1 << 1);
+
+    if (Opts.isSignReturnAddressScopeAll())
+      Value |= (1 << 2);
+
+    Builder.defineMacro("__ARM_FEATURE_PAC_DEFAULT", std::to_string(Value));
+  }
+
+  if (Opts.BranchTargetEnforcement)
+    Builder.defineMacro("__ARM_FEATURE_BTI_DEFAULT", "1");
+
   switch (ArchKind) {
   default:
     break;
diff --git a/clang/test/Preprocessor/aarch64-target-features.c b/clang/test/Preprocessor/aarch64-target-features.c
--- a/clang/test/Preprocessor/aarch64-target-features.c
+++ b/clang/test/Preprocessor/aarch64-target-features.c
@@ -39,6 +39,8 @@
 // CHECK-NOT: __ARM_SIZEOF_WCHAR_T 2
 // CHECK-NOT: __ARM_FEATURE_SVE
 // CHECK-NOT: __ARM_FEATURE_DOTPROD
+// CHECK-NOT: __ARM_FEATURE_PAC_DEFAULT
+// CHECK-NOT: __ARM_FEATURE_BTI_DEFAULT
 
 // RUN: %clang -target aarch64-none-linux-gnu -march=armv8-a+crypto -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-CRYPTO %s
 // RUN: %clang -target arm64-none-linux-gnu -march=armv8-a+crypto -x c -E -dM %s -o - | FileCheck --check-prefix=CHECK-CRYPTO %s
@@ -334,3 +336,33 @@
 // ================== Check Memory Tagging Extensions (MTE).
 // RUN: %clang -target arm64-none-linux-gnu -march=armv8.5-a+memtag -x c -E -dM %s -o - 2>&1 | FileCheck -check-prefix=CHECK-MEMTAG %s
 // CHECK-MEMTAG: __ARM_FEATURE_MEMORY_TAGGING 1
+
+// ================== Check Pointer Authentication Extension (PAuth).
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8.5-a -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=none -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=bti -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=standard -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret+b-key -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH-BKEY %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret+leaf -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH-ALL %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret+leaf+b-key -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-PAUTH-BKEY-ALL %s
+// CHECK-PAUTH-OFF-NOT:  __ARM_FEATURE_PAC_DEFAULT
+// CHECK-PAUTH:          #define __ARM_FEATURE_PAC_DEFAULT 1
+// CHECK-PAUTH-BKEY:     #define __ARM_FEATURE_PAC_DEFAULT 2
+// CHECK-PAUTH-ALL:      #define __ARM_FEATURE_PAC_DEFAULT 5
+// CHECK-PAUTH-BKEY-ALL: #define __ARM_FEATURE_PAC_DEFAULT 6
+
+// ================== Check Branch Target Identification (BTI).
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8.5-a -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=none -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret+leaf -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret+b-key -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret+leaf+b-key -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI-OFF %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=standard -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=bti -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI %s
+// RUN: %clang -target arm64-none-linux-gnu -march=armv8-a -mbranch-protection=pac-ret+bti -x c -E -dM %s -o - | FileCheck -check-prefix=CHECK-BTI %s
+// CHECK-BTI-OFF-NOT: __ARM_FEATURE_BTI_DEFAULT
+// CHECK-BTI:         #define __ARM_FEATURE_BTI_DEFAULT 1