Index: clang/lib/Driver/Driver.cpp
===================================================================
--- clang/lib/Driver/Driver.cpp
+++ clang/lib/Driver/Driver.cpp
@@ -3998,10 +3998,13 @@
   }
 
   const llvm::Triple &RawTriple = C.getDefaultToolChain().getTriple();
-  if (RawTriple.isOSAIX())
+  if (RawTriple.isOSAIX()) {
     if (Arg *A = C.getArgs().getLastArg(options::OPT_G))
       Diag(diag::err_drv_unsupported_opt_for_target)
           << A->getSpelling() << RawTriple.str();
+    if (LTOMode == LTOK_Thin)
+      Diag(diag::err_drv_clang_unsupported) << "thinLTO on AIX";
+  }
 
   // Collect the list of architectures.
   llvm::StringSet<> ArchNames;
Index: clang/test/Driver/aix-err-options.c
===================================================================
--- clang/test/Driver/aix-err-options.c
+++ clang/test/Driver/aix-err-options.c
@@ -26,3 +26,10 @@
 
 // CHECK32: error: unsupported option '-G' for target 'powerpc-ibm-aix-xcoff'
 // CHECK64: error: unsupported option '-G' for target 'powerpc64-ibm-aix-xcoff'
+
+// RUN: %clang -target powerpc-ibm-aix-xcoff -### -flto=thin 2>&1 %s | \
+// RUN:   FileCheck --check-prefix=CHECKTHINLTO %s
+// RUN: %clang -target powerpc64-ibm-aix-xcoff -### -flto=thin 2>&1 %s | \
+// RUN:   FileCheck --check-prefix=CHECKTHINLTO %s
+
+// CHECKTHINLTO: error: the clang compiler does not support 'thinLTO on AIX'