diff --git a/llvm/tools/llvm-ar/llvm-ar.cpp b/llvm/tools/llvm-ar/llvm-ar.cpp
--- a/llvm/tools/llvm-ar/llvm-ar.cpp
+++ b/llvm/tools/llvm-ar/llvm-ar.cpp
@@ -1179,16 +1179,16 @@
   llvm::InitializeAllAsmParsers();
 
   Stem = sys::path::stem(ToolName);
-  if (Stem.contains_lower("dlltool"))
+  if (Stem.endswith_lower("dlltool"))
     return dlltoolDriverMain(makeArrayRef(argv, argc));
 
-  if (Stem.contains_lower("ranlib"))
+  if (Stem.endswith_lower("ranlib"))
     return ranlib_main(argc, argv);
 
-  if (Stem.contains_lower("lib"))
+  if (Stem.endswith_lower("lib"))
     return libDriverMain(makeArrayRef(argv, argc));
 
-  if (Stem.contains_lower("ar"))
+  if (Stem.endswith_lower("ar"))
     return ar_main(argc, argv);
   fail("not ranlib, ar, lib or dlltool");
 }