diff --git a/clang/include/clang/Basic/DiagnosticDriverKinds.td b/clang/include/clang/Basic/DiagnosticDriverKinds.td
--- a/clang/include/clang/Basic/DiagnosticDriverKinds.td
+++ b/clang/include/clang/Basic/DiagnosticDriverKinds.td
@@ -428,8 +428,6 @@
   "invalid branch protection option '%0' in '%1'">;
 def warn_unsupported_branch_protection: Warning <
   "invalid branch protection option '%0' in '%1'">, InGroup<BranchProtection>;
-def err_invalid_sls_hardening : Error<
-  "invalid sls hardening option '%0' in '%1'">;
 def err_sls_hardening_arm_not_supported : Error<
   "-mharden-sls is only supported on armv7-a or later">;
 
diff --git a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
--- a/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/AArch64.cpp
@@ -324,8 +324,8 @@
           DisableComdat = true;
           continue;
         }
-        D.Diag(diag::err_invalid_sls_hardening)
-            << Scope << A->getAsString(Args);
+        D.Diag(diag::err_drv_unsupported_option_argument)
+            << A->getOption().getName() << Scope;
         break;
       }
     }
diff --git a/clang/lib/Driver/ToolChains/Arch/ARM.cpp b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
--- a/clang/lib/Driver/ToolChains/Arch/ARM.cpp
+++ b/clang/lib/Driver/ToolChains/Arch/ARM.cpp
@@ -868,8 +868,8 @@
           DisableComdat = true;
           continue;
         }
-        D.Diag(diag::err_invalid_sls_hardening)
-            << Scope << A->getAsString(Args);
+        D.Diag(diag::err_drv_unsupported_option_argument)
+            << A->getOption().getName() << Scope;
         break;
       }
     }
diff --git a/clang/test/Driver/sls-hardening-options.c b/clang/test/Driver/sls-hardening-options.c
--- a/clang/test/Driver/sls-hardening-options.c
+++ b/clang/test/Driver/sls-hardening-options.c
@@ -99,7 +99,7 @@
 // NOCOMDAT-OFF-NOT: "harden-sls-nocomdat"
 // NOCOMDAT: "+harden-sls-nocomdat"
 
-// BAD-SLS-SPEC: invalid sls hardening option '{{[^']+}}' in '-mharden-sls=
+// BAD-SLS-SPEC: unsupported argument '{{[^']+}}' to option '-mharden-sls='
 
 // RUN: %clang -target armv6a--none-eabi -c %s -### -mharden-sls=all 2>&1 | \
 // RUN: FileCheck %s --check-prefix=SLS-NOT-SUPPORTED