Index: llvm/tools/llvm-ar/llvm-ar.cpp
--- llvm/tools/llvm-ar/llvm-ar.cpp.orig
+++ llvm/tools/llvm-ar/llvm-ar.cpp
@@ -1463,8 +1463,12 @@ static int ranlib_main(int argc, char **argv) {
                  " option not supported on non AIX OS");
           }
           break;
+        } else if (arg.front() == 't') {
+          // GNU ranlib also supports a -t flag, but does nothing
+          // because it just returns true without touching the
+          // timestamp, so simulate the same behaviour.
+          return 0;
         } else {
-          // TODO: GNU ranlib also supports a -t flag
           fail("Invalid option: '-" + arg + "'");
         }
         arg = arg.drop_front(1);
