diff --git a/lld/COFF/Driver.cpp b/lld/COFF/Driver.cpp
--- a/lld/COFF/Driver.cpp
+++ b/lld/COFF/Driver.cpp
@@ -473,7 +473,7 @@
   }
 
   if (path.endswith_insensitive(".lib"))
-    visitedLibs.insert(std::string(sys::path::filename(path)));
+    visitedLibs.insert(std::string(sys::path::filename(path).lower()));
   return path;
 }