diff --git a/clang/lib/Driver/ToolChains/Clang.cpp b/clang/lib/Driver/ToolChains/Clang.cpp
index 837ead86d62026..75bc32916371b5 100644
--- a/clang/lib/Driver/ToolChains/Clang.cpp
+++ b/clang/lib/Driver/ToolChains/Clang.cpp
@@ -4841,6 +4841,14 @@ void Clang::ConstructJob(Compilation &C, const JobAction &JA,
       CmdArgs.push_back("-mabi=vec-default");
   }
 
+  if (Arg *A = Args.getLastArg(options::OPT_mlong_double_128)) {
+    // Emit the unsupported option error until the Clang's library integration
+    // support for 128-bit long double is available for AIX.
+    if (Triple.isOSAIX())
+      D.Diag(diag::err_drv_unsupported_opt_for_target)
+          << A->getSpelling() << RawTriple.str();
+  }
+
   if (Arg *A = Args.getLastArg(options::OPT_Wframe_larger_than_EQ)) {
     StringRef v = A->getValue();
     // FIXME: Validate the argument here so we don't produce meaningless errors
diff --git a/clang/test/Driver/unsupported-option.c b/clang/test/Driver/unsupported-option.c
index 975440352259d0..c263bb0b853c5a 100644
--- a/clang/test/Driver/unsupported-option.c
+++ b/clang/test/Driver/unsupported-option.c
@@ -21,3 +21,11 @@
 // RUN: not %clang -fprofile-generate -flto=thin --target=powerpc64-ibm-aix %s 2>&1 | \
 // RUN: FileCheck %s --check-prefix=AIX-PROFILE-THINLTO
 // AIX-PROFILE-THINLTO: error: invalid argument '-fprofile-generate' only allowed with '-flto'
+
+// RUN: not %clang --target=powerpc-ibm-aix %s -mlong-double-128 2>&1 | \
+// RUN: FileCheck %s --check-prefix=AIX-LONGDOUBLE128-ERR
+// AIX-LONGDOUBLE128-ERR: error: unsupported option '-mlong-double-128' for target 'powerpc-ibm-aix'
+
+// RUN: not %clang --target=powerpc64-ibm-aix %s -mlong-double-128 2>&1 | \
+// RUN: FileCheck %s --check-prefix=AIX64-LONGDOUBLE128-ERR
+// AIX64-LONGDOUBLE128-ERR: error: unsupported option '-mlong-double-128' for target 'powerpc64-ibm-aix'