Standardize shortname
diff --git a/tools/run_tests/run_tests.py b/tools/run_tests/run_tests.py
index 4c4deb4..4c3db14 100755
--- a/tools/run_tests/run_tests.py
+++ b/tools/run_tests/run_tests.py
@@ -345,7 +345,7 @@
               if not test: continue
               cmdline = [binary, '--benchmark_filter=%s$' % test] + target['args']
               out.append(self.config.job_spec(cmdline,
-                                              shortname='%s:%s %s' % (binary, test, shortname_ext),
+                                              shortname='%s %s' % (' '.join(cmdline), shortname_ext),
                                               cpu_cost=cpu_cost,
                                               timeout_seconds=_DEFAULT_TIMEOUT_SECONDS * timeout_scaling,
                                               environ=env))