--- a/services/sync/tps/extensions/mozmill/install.rdf
+++ b/services/sync/tps/extensions/mozmill/install.rdf
@@ -15,10 +15,11 @@
 
      <em:targetApplication>
        <Description>
          <em:id>toolkit@mozilla.org</em:id>
          <em:minVersion>10.0</em:minVersion>
          <em:maxVersion>38.*</em:maxVersion>
        </Description>
      </em:targetApplication>
+     <em:multiprocessCompatible>true</em:multiprocessCompatible>
    </Description>
 </RDF>

--- a/services/sync/tps/extensions/tps/components/tps-cmdline.js
+++ b/services/sync/tps/extensions/tps/components/tps-cmdline.js
@@ -15,16 +15,17 @@ const nsICategoryManager             = C
 const nsICmdLineHandler              = Components.interfaces.nsICmdLineHandler;
 const nsICommandLine                 = Components.interfaces.nsICommandLine;
 const nsICommandLineHandler          = Components.interfaces.nsICommandLineHandler;
 const nsIComponentRegistrar          = Components.interfaces.nsIComponentRegistrar;
 const nsISupportsString              = Components.interfaces.nsISupportsString;
 const nsIWindowWatcher               = Components.interfaces.nsIWindowWatcher;
 
 Components.utils.import("resource://gre/modules/XPCOMUtils.jsm");
+Components.utils.import("resource://gre/modules/Services.jsm");
 
 function TPSCmdLineHandler() {}
 
 TPSCmdLineHandler.prototype = {
   classDescription: "TPSCmdLineHandler",
   classID: TPS_CMDLINE_CLSID,
   contractID: TPS_CMDLINE_CONTRACTID,
 
@@ -51,30 +52,30 @@ TPSCmdLineHandler.prototype = {
     if (phase == null)
         throw Error("must specify --tpsphase with --tps");
     let logfile = cmdLine.handleFlagWithParam("tpslogfile", false);
     if (logfile == null)
         logfile = "";
 
     options.ignoreUnusedEngines = cmdLine.handleFlag("ignore-unused-engines",
                                                      false);
-
+    let uri = cmdLine.resolveURI(uristr).spec;
 
-    /* Ignore the platform's online/offline status while running tests. */
-    var ios = Components.classes["@mozilla.org/network/io-service;1"]
-              .getService(Components.interfaces.nsIIOService2);
-    ios.manageOfflineStatus = false;
-    ios.offline = false;
-
-    Components.utils.import("resource://tps/tps.jsm");
-    Components.utils.import("resource://tps/quit.js", TPS);
-    let uri = cmdLine.resolveURI(uristr).spec;
-    TPS.RunTestPhase(uri, phase, logfile, options);
-
-    // cmdLine.preventDefault = true;
+    const onStartupFinished = () => {
+      Services.obs.removeObserver(onStartupFinished, "browser-delayed-startup-finished");
+      /* Ignore the platform's online/offline status while running tests. */
+      var ios = Components.classes["@mozilla.org/network/io-service;1"]
+                .getService(Components.interfaces.nsIIOService2);
+      ios.manageOfflineStatus = false;
+      ios.offline = false;
+      Components.utils.import("resource://tps/tps.jsm");
+      Components.utils.import("resource://tps/quit.js", TPS);
+      TPS.RunTestPhase(uri, phase, logfile, options);
+    };
+    Services.obs.addObserver(onStartupFinished, "browser-delayed-startup-finished");
   },
 
   helpInfo: "  --tps <file>              Run TPS tests with the given test file.\n" +
             "  --tpsphase <phase>        Run the specified phase in the TPS test.\n" +
             "  --tpslogfile <file>       Logfile for TPS output.\n" +
             "  --ignore-unused-engines   Don't load engines not used in tests.\n",
 };
 

--- a/services/sync/tps/extensions/tps/install.rdf
+++ b/services/sync/tps/extensions/tps/install.rdf
@@ -19,10 +19,11 @@
     </em:targetApplication>
 
     <!-- front-end metadata -->
     <em:name>TPS</em:name>
     <em:description>Sync test extension</em:description>
     <em:creator>Jonathan Griffin</em:creator>
     <em:contributor>Henrik Skupin</em:contributor>
     <em:homepageURL>https://developer.mozilla.org/en-US/docs/TPS</em:homepageURL>
+    <em:multiprocessCompatible>true</em:multiprocessCompatible>
   </Description>
 </RDF>

--- a/services/sync/tps/extensions/tps/resource/tps.jsm
+++ b/services/sync/tps/extensions/tps/resource/tps.jsm
@@ -895,20 +895,19 @@ var TPS = {
    * This is called by RunTestPhase() after the environment is validated.
    */
   _executeTestPhase: function _executeTestPhase(file, phase, settings) {
     try {
       this.config = JSON.parse(prefs.getCharPref("tps.config"));
       // parse the test file
       Services.scriptloader.loadSubScript(file, this);
       this._currentPhase = phase;
+      // cleanup phases are in the format `cleanup-${profileName}`.
       if (this._currentPhase.startsWith("cleanup-")) {
-        let profileToClean = Cc["@mozilla.org/toolkit/profile-service;1"]
-                             .getService(Ci.nsIToolkitProfileService)
-                             .selectedProfile.name;
+        let profileToClean = this._currentPhase.slice("cleanup-".length);
         this.phases[this._currentPhase] = profileToClean;
         this.Phase(this._currentPhase, [[this.Cleanup]]);
       } else {
         // Don't bother doing this for cleanup phases.
         this._tryLoadPingSchema(file);
       }
       let this_phase = this._phaselist[this._currentPhase];
 

--- a/testing/tps/tps/testrunner.py
+++ b/testing/tps/tps/testrunner.py
@@ -72,16 +72,17 @@ class TPSTestRunner(object):
         # Don't open a dialog to show available add-on updates
         'extensions.update.notifyUser': False,
         'services.sync.firstSync': 'notReady',
         'services.sync.lastversion': '1.0',
         'toolkit.startup.max_resumed_crashes': -1,
         # hrm - not sure what the release/beta channels will do?
         'xpinstall.signatures.required': False,
         'services.sync.testing.tps': True,
+        'engine.bookmarks.repair.enabled': False,
     }
 
     debug_preferences = {
         'services.sync.log.appender.console': 'Trace',
         'services.sync.log.appender.dump': 'Trace',
         'services.sync.log.appender.file.level': 'Trace',
         'services.sync.log.appender.file.logOnSuccess': True,
         'services.sync.log.rootLogger': 'Trace',