Index: llvm/tools/llvm-ar/llvm-ar.cpp
===================================================================
--- llvm/tools/llvm-ar/llvm-ar.cpp
+++ llvm/tools/llvm-ar/llvm-ar.cpp
@@ -855,11 +855,11 @@
   llvm::InitializeAllAsmParsers();
 
   StringRef Stem = sys::path::stem(ToolName);
-  if (Stem.find("dlltool") != StringRef::npos)
+  if (Stem.find_lower("dlltool") != StringRef::npos)
     return dlltoolDriverMain(makeArrayRef(argv, argc));
 
-  if (Stem.find("ranlib") == StringRef::npos &&
-      Stem.find("lib") != StringRef::npos)
+  if (Stem.find_lower("ranlib") == StringRef::npos &&
+      Stem.find_lower("lib") != StringRef::npos)
     return libDriverMain(makeArrayRef(argv, argc));
 
   for (int i = 1; i < argc; i++) {
@@ -887,9 +887,9 @@
     "  This program archives bitcode files into single libraries\n"
   );
 
-  if (Stem.find("ranlib") != StringRef::npos)
+  if (Stem.find_lower("ranlib") != StringRef::npos)
     return ranlib_main();
-  if (Stem.find("ar") != StringRef::npos)
+  if (Stem.find_lower("ar") != StringRef::npos)
     return ar_main();
   fail("Not ranlib, ar, lib or dlltool!");
 }