Index: include/clang/Driver/Options.td
===================================================================
--- include/clang/Driver/Options.td
+++ include/clang/Driver/Options.td
@@ -2045,9 +2045,9 @@
 def ffixed_x20 : Flag<["-"], "ffixed-x20">, Group<m_aarch64_Features_Group>,
   HelpText<"Reserve the x20 register (AArch64 only)">;
 
-def msign_return_address : Joined<["-"], "msign-return-address=">,
-  Flags<[CC1Option]>, Group<m_Group>,
-  HelpText<"Select return address signing scope">, Values<"none,all,non-leaf">;
+def msign_return_address_EQ : Joined<["-"], "msign-return-address=">,
+  Flags<[CC1Option]>, Group<m_Group>, Values<"none,all,non-leaf[+a_key,b_key]">,
+  HelpText<"Select return address signing scope">;
 
 def msimd128 : Flag<["-"], "msimd128">, Group<m_wasm_Features_Group>;
 def mno_simd128 : Flag<["-"], "mno-simd128">, Group<m_wasm_Features_Group>;
Index: include/clang/Frontend/CodeGenOptions.h
===================================================================
--- include/clang/Frontend/CodeGenOptions.h
+++ include/clang/Frontend/CodeGenOptions.h
@@ -114,6 +114,8 @@
     All      // Sign the return address of all functions
   };
 
+  enum SignReturnAddressKeyValue { AKey, BKey };
+
   /// The code model to use (-mcmodel).
   std::string CodeModel;
 
Index: include/clang/Frontend/CodeGenOptions.def
===================================================================
--- include/clang/Frontend/CodeGenOptions.def
+++ include/clang/Frontend/CodeGenOptions.def
@@ -340,6 +340,7 @@
 CODEGENOPT(Addrsig, 1, 0)
 
 ENUM_CODEGENOPT(SignReturnAddress, SignReturnAddressScope, 2, None)
+ENUM_CODEGENOPT(SignReturnAddressKey, SignReturnAddressKeyValue, 1, AKey)
 
 /// Whether to emit unused static constants.
 CODEGENOPT(KeepStaticConsts, 1, 0)
Index: lib/CodeGen/TargetInfo.cpp
===================================================================
--- lib/CodeGen/TargetInfo.cpp
+++ lib/CodeGen/TargetInfo.cpp
@@ -4985,6 +4985,12 @@
                   Kind == CodeGenOptions::SignReturnAddressScope::All
                       ? "all"
                       : "non-leaf");
+
+    auto Key = CGM.getCodeGenOpts().getSignReturnAddressKey();
+    Fn->addFnAttr("sign-return-address-key",
+                  Key == CodeGenOptions::SignReturnAddressKeyValue::AKey
+                      ? "a_key"
+                      : "b_key");
   }
 };
 
Index: lib/Driver/ToolChains/Clang.cpp
===================================================================
--- lib/Driver/ToolChains/Clang.cpp
+++ lib/Driver/ToolChains/Clang.cpp
@@ -1456,7 +1456,7 @@
       CmdArgs.push_back("-aarch64-enable-global-merge=true");
   }
 
-  if (Arg *A = Args.getLastArg(options::OPT_msign_return_address)) {
+  if (Arg *A = Args.getLastArg(options::OPT_msign_return_address_EQ)) {
     CmdArgs.push_back(
         Args.MakeArgString(Twine("-msign-return-address=") + A->getValue()));
   }
Index: lib/Frontend/CompilerInvocation.cpp
===================================================================
--- lib/Frontend/CompilerInvocation.cpp
+++ lib/Frontend/CompilerInvocation.cpp
@@ -1131,8 +1131,11 @@
 
   Opts.Addrsig = Args.hasArg(OPT_faddrsig);
 
-  if (Arg *A = Args.getLastArg(OPT_msign_return_address)) {
-    StringRef SignScope = A->getValue();
+  if (Arg *A = Args.getLastArg(OPT_msign_return_address_EQ)) {
+    const auto SignScopeKey = StringRef(A->getValue()).split('+');
+    StringRef SignScope = SignScopeKey.first;
+    StringRef SignKey = SignScopeKey.second;
+
     if (SignScope.equals_lower("none"))
       Opts.setSignReturnAddress(CodeGenOptions::SignReturnAddressScope::None);
     else if (SignScope.equals_lower("all"))
@@ -1142,7 +1145,17 @@
           CodeGenOptions::SignReturnAddressScope::NonLeaf);
     else
       Diags.Report(diag::err_drv_invalid_value)
-          << A->getAsString(Args) << A->getValue();
+          << A->getAsString(Args) << SignScope;
+
+    if (!SignScope.empty() && !SignKey.empty()) {
+      if (SignKey.equals_lower("a_key"))
+        Opts.setSignReturnAddressKey(CodeGenOptions::SignReturnAddressKeyValue::AKey);
+      else if (SignKey.equals_lower("b_key"))
+        Opts.setSignReturnAddressKey(CodeGenOptions::SignReturnAddressKeyValue::BKey);
+      else
+        Diags.Report(diag::err_drv_invalid_value) << A->getAsString(Args)
+                                                  << SignKey;
+    }
   }
 
   Opts.KeepStaticConsts = Args.hasArg(OPT_fkeep_static_consts);
Index: test/CodeGen/aarch64-sign-return-address.c
===================================================================
--- test/CodeGen/aarch64-sign-return-address.c
+++ test/CodeGen/aarch64-sign-return-address.c
@@ -1,6 +1,8 @@
 // RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=none  %s | FileCheck %s --check-prefix=CHECK-NONE
 // RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=non-leaf %s | FileCheck %s --check-prefix=CHECK-PARTIAL
 // RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=all %s | FileCheck %s --check-prefix=CHECK-ALL
+// RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=all+a_key %s | FileCheck %s --check-prefix=CHECK-A-KEY
+// RUN: %clang -target aarch64-arm-none-eabi -S -emit-llvm -o - -msign-return-address=all+b_key %s | FileCheck %s --check-prefix=CHECK-B-KEY
 
 // CHECK-NONE: @foo() #[[ATTR:[0-9]*]]
 // CHECK-NONE-NOT: attributes #[[ATTR]] = { {{.*}} "sign-return-address"={{.*}} }}
@@ -11,4 +13,10 @@
 // CHECK-ALL: @foo() #[[ATTR:[0-9]*]]
 // CHECK-ALL: attributes #[[ATTR]] = { {{.*}} "sign-return-address"="all" {{.*}} }
 
+// CHECK-A-KEY: @foo() #[[ATTR:[0-9]*]]
+// CHECK-A-KEY: attributes #[[ATTR]] = { {{.*}} "sign-return-address"="all" "sign-return-address-key"="a_key" {{.*}} }
+
+// CHECK-B-KEY: @foo() #[[ATTR:[0-9]*]]
+// CHECK-B-KEY: attributes #[[ATTR]] = { {{.*}} "sign-return-address"="all" "sign-return-address-key"="b_key" {{.*}} }
+
 void foo() {}