--- a/testing/mochitest/mochitest_options.py
+++ b/testing/mochitest/mochitest_options.py
@@ -724,17 +724,16 @@ class MochitestArguments(ArgumentContain
             options.symbolsPath = os.path.join(build_obj.distdir, 'crashreporter-symbols')
 
         if options.jsdebugger:
             options.extraPrefs += [
                 "devtools.debugger.remote-enabled=true",
                 "devtools.chrome.enabled=true",
                 "devtools.debugger.prompt-connection=false"
             ]
-            options.autorun = False
 
         if options.debugOnFailure and not options.jsdebugger:
             parser.error(
                 "--debug-on-failure requires --jsdebugger.")
 
         if options.debuggerArgs and not options.debugger:
             parser.error(
                 "--debugger-args requires --debugger.")

--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -2414,17 +2414,17 @@ toolbar#nav-bar {
         try:
             self.startServers(options, debuggerInfo)
 
             if options.immersiveMode:
                 options.browserArgs.extend(('-firefoxpath', options.app))
                 options.app = self.immersiveHelperPath
 
             if options.jsdebugger:
-                options.browserArgs.extend(['-jsdebugger'])
+                options.browserArgs.extend(['-jsdebugger', '-wait-for-jsdebugger'])
 
             # Remove the leak detection file so it can't "leak" to the tests run.
             # The file is not there if leak logging was not enabled in the
             # application build.
             if os.path.exists(self.leak_report_file):
                 os.remove(self.leak_report_file)
 
             # then again to actually run mochitest