diff --git a/llvm/lib/Analysis/TargetLibraryInfo.cpp b/llvm/lib/Analysis/TargetLibraryInfo.cpp
index 7ce42447b6308a..592caf2d0e23a0 100644
--- a/llvm/lib/Analysis/TargetLibraryInfo.cpp
+++ b/llvm/lib/Analysis/TargetLibraryInfo.cpp
@@ -882,6 +882,9 @@ static void initializeLibCalls(TargetLibraryInfoImpl &TLI, const Triple &T,
     TLI.setUnavailable(LibFunc_vec_free);
   }
 
+  if (T.isOSAIX())
+    TLI.setUnavailable(LibFunc_memrchr);
+
   TLI.addVectorizableFunctionsFromVecLib(ClVectorLibrary, T);
 }