diff --git a/build/pgo/automation.py.in b/build/pgo/automation.py.in
index 58dc21600c7d..a934775427d7 100644
--- a/build/pgo/automation.py.in
+++ b/build/pgo/automation.py.in
@@ -247,7 +247,7 @@ user_pref("network.proxy.autoconfig_url", "%(pacURL)s");
 # RUN THE APP         #
 #######################
 
-def runApp(testURL, env, app, profileDir):
+def runApp(testURL, env, app, profileDir, extraArgs):
   "Run the app, returning the time at which it was started."
   # mark the start
   start = datetime.now()
@@ -268,6 +268,7 @@ def runApp(testURL, env, app, profileDir):
     profileDirectory = profileDir + "/"
 
   args.extend(("-no-remote", "-profile", profileDirectory, testURL))
+  args.extend(extraArgs)
   proc = Process(cmd, args, env = env)
   print "Application pid: " + str(proc.pid)
   status = proc.wait()
diff --git a/build/pgo/profileserver.py.in b/build/pgo/profileserver.py.in
index 5c008a51f3f4..152c1caf08e1 100644
--- a/build/pgo/profileserver.py.in
+++ b/build/pgo/profileserver.py.in
@@ -74,4 +74,5 @@ if __name__ == '__main__':
     browserEnv["MOZILLA_FIVE_HOME"] = os.path.join(SCRIPT_DIR, automation.DIST_BIN)
 
   automation.runApp("http://localhost:%d/index.html" % PORT, browserEnv,
-                    os.path.join(SCRIPT_DIR, automation.DEFAULT_APP), PROFILE_DIRECTORY)
+                    os.path.join(SCRIPT_DIR, automation.DEFAULT_APP),
+                    PROFILE_DIRECTORY, ())
diff --git a/testing/mochitest/runtests.py.in b/testing/mochitest/runtests.py.in
index fed850d025c5..2eb1d90056b0 100644
--- a/testing/mochitest/runtests.py.in
+++ b/testing/mochitest/runtests.py.in
@@ -162,7 +162,7 @@ class MochitestOptions(optparse.OptionParser):
                            "refcounted objects (or bytes in classes with "
                            "MOZ_COUNT_CTOR and MOZ_COUNT_DTOR) is greater "
                            "than the given number")
-    defaults["leakThreshold"] = -1
+    defaults["leakThreshold"] = 0
 
     # -h, --help are automatically handled by OptionParser
 
@@ -326,7 +326,8 @@ Are you executing $objdir/_tests/testing/mochitest/runtests.py?"""
   if options.leakThreshold >= 0:
     browserEnv["XPCOM_MEM_BLOAT_LOG"] = LEAK_REPORT_FILE
 
-  start = automation.runApp(testURL, browserEnv, options.app, PROFILE_DIRECTORY)
+  start = automation.runApp(testURL, browserEnv, options.app, PROFILE_DIRECTORY,
+                            options.browserArgs)
 
   server.stop()