diff --git a/build/pgo/profileserver.py.in b/build/pgo/profileserver.py.in
index e4f8886aace..3270fbb873a 100644
--- a/build/pgo/profileserver.py.in
+++ b/build/pgo/profileserver.py.in
@@ -70,6 +70,9 @@ if __name__ == '__main__':
   appPath = os.path.join(SCRIPT_DIR, automation.DEFAULT_APP)
   status = automation.runApp(url, browserEnv, appPath, PROFILE_DIRECTORY, {},
                              # the profiling HTML doesn't output anything,
-                             # so let's just ignore this for now.
-                             timeout = None)
+                             # so let's just set this really high for now.
+                             #FIXME: the POSIX codepath accepts None
+                             # as "no timeout", the Windows codepath
+                             # should too.
+                             timeout = 1800.0)
   sys.exit(status)
diff --git a/testing/mochitest/runtests.py.in b/testing/mochitest/runtests.py.in
index e15b8d4f0d1..16a9d6ae6ff 100644
--- a/testing/mochitest/runtests.py.in
+++ b/testing/mochitest/runtests.py.in
@@ -456,10 +456,13 @@ Are you executing $objdir/_tests/testing/mochitest/runtests.py?"""
     os.remove(LEAK_REPORT_FILE)
 
   # then again to actually run mochitest
-  # don't use a timeout if we're not auto-running
-  #XXX: use the value from --timeout when bug 521130 lands, for now
-  # use the Mochitest JS harness's timeout + 30 seconds
-  timeout = options.autorun and 330.0 or None
+  if options.timeout:
+      timeout = options.timeout + 30
+  elif options.autorun:
+      #FIXME: need to support None for timeout values on Win32
+      timeout = 1000000
+  else:
+      timeout = 330.0 # default JS harness timeout is 300 seconds
   automation.log.info("INFO | runtests.py | Running tests: start.\n")
   status = automation.runApp(testURL, browserEnv, options.app,
                              PROFILE_DIRECTORY, options.browserArgs,