diff --git a/testing/config/mozharness/b2g_emulator_config.py b/testing/config/mozharness/b2g_emulator_config.py
index d93827c6ef8..40aa6b008db 100644
--- a/testing/config/mozharness/b2g_emulator_config.py
+++ b/testing/config/mozharness/b2g_emulator_config.py
@@ -72,7 +72,7 @@ config = {
                 "--quiet",
                 "--log-raw=%(raw_log_file)s",
                 "--certificate-path=%(certificate_path)s",
-                "--test-path=%(test_path)s"
+                "%(test_path)s"
             ],
             "run_filename": "runtestsb2g.py",
             "testsdir": "mochitest"
@@ -93,7 +93,7 @@ config = {
                 "--chrome",
                 "--log-raw=%(raw_log_file)s",
                 "--certificate-path=%(certificate_path)s",
-                "--test-path=%(test_path)s"
+                "%(test_path)s"
             ],
             "run_filename": "runtestsb2g.py",
             "testsdir": "mochitest"
diff --git a/testing/mochitest/bisection.py b/testing/mochitest/bisection.py
index 5ffd2771922..9c6d69d2b51 100644
--- a/testing/mochitest/bisection.py
+++ b/testing/mochitest/bisection.py
@@ -10,8 +10,6 @@ class Bisect(object):
         super(Bisect, self).__init__()
         self.summary = []
         self.contents = {}
-        self.testRoot = harness.testRoot
-        self.testRootAbs = harness.testRootAbs
         self.repeat = 10
         self.failcount = 0
         self.max_failures = 3
diff --git a/testing/mochitest/browser-harness.xul b/testing/mochitest/browser-harness.xul
index 388cb5810e7..cbf8d18b6ee 100644
--- a/testing/mochitest/browser-harness.xul
+++ b/testing/mochitest/browser-harness.xul
@@ -100,14 +100,7 @@
     function TestStart() {
       gConfig = readConfig();
 
-      // If MochiTest was started with the --test-path flag specifying a subset
-      // of tests to run, put that path in the label of the "Run Tests" button
-      // so the tester knows which tests will run when they press that button.
-      if (gConfig.testPath)
-        document.getElementById("runTestsButton").label =
-          "Run " + gConfig.testPath + " tests";
-
-      // Similarly, update the title for --start-at and --end-at.
+      // Update the title for --start-at and --end-at.
       if (gConfig.startAt || gConfig.endAt)
         document.getElementById("runTestsButton").label =
           "Run subset of tests";
diff --git a/testing/mochitest/browser-test.js b/testing/mochitest/browser-test.js
index 48dd88f1db6..edac456e0f3 100644
--- a/testing/mochitest/browser-test.js
+++ b/testing/mochitest/browser-test.js
@@ -350,7 +350,7 @@ Tester.prototype = {
         this.dumper.structuredLogger.testEnd("browser-test.js",
                                              "FAIL",
                                              "PASS",
-                                             "No tests to run. Did you pass an invalid --test-path?");
+                                             "No tests to run. Did you pass invalid test_paths?");
       }
       this.dumper.structuredLogger.info("*** End BrowserChrome Test Results ***");
 
diff --git a/testing/mochitest/chrome-harness.js b/testing/mochitest/chrome-harness.js
index 83e8c5c67ec..569fa2ce608 100644
--- a/testing/mochitest/chrome-harness.js
+++ b/testing/mochitest/chrome-harness.js
@@ -57,62 +57,6 @@ function getChromeDir(resolvedURI) {
   return chromeDir.parent.QueryInterface(Components.interfaces.nsILocalFile);
 }
 
-/**
- * basePath: the URL base path to search from such as chrome://mochikit/content/a11y
- * testPath: the optional testPath passed into the test such as dom/tests/mochitest
- * dir: the test dir to append to the uri after getting a directory interface
- * srvScope: loaded javascript to server.js so we have aComponents.classesess to the list() function
- *
- * return value:
- *  single test: [json object, path to test]
- *  list of tests: [json object, null] <- directory [heirarchy]
- */
-function getFileListing(basePath, testPath, dir, srvScope)
-{
-  var uri = getResolvedURI(basePath);
-  var chromeDir = getChromeDir(uri);
-  chromeDir.appendRelativePath(dir);
-  basePath += '/' + dir.replace(/\\/g, '/');
-
-  if (testPath == "false" || testPath == false) {
-    testPath = "";
-  }
-  testPath = testPath.replace(/\\\\/g, '\\').replace(/\\/g, '/');
-
-  var ioSvc = Components.classes["@mozilla.org/network/io-service;1"].
-              getService(Components.interfaces.nsIIOService);
-  var testsDirURI = ioSvc.newFileURI(chromeDir);
-  var testsDir = ioSvc.newURI(testPath, null, testsDirURI)
-                  .QueryInterface(Components.interfaces.nsIFileURL).file;
-
-  if (testPath != undefined) {
-    var extraPath = testPath;
-
-    var fileNameRegexp = /(browser|test)_.+\.(xul|html|js)$/;
-
-    // Invalid testPath...
-    if (!testsDir.exists())
-      return null;
-
-    if (testsDir.isFile()) {
-      if (fileNameRegexp.test(testsDir.leafName)) {
-        var singlePath = basePath + '/' + testPath;
-        var links = {};
-        links[singlePath] = true;
-        return links;
-      }
-      // We were passed a file that's not a test...
-      return null;
-    }
-
-    // otherwise, we were passed a directory of tests
-    basePath += "/" + testPath;
-  }
-  var [links, count] = srvScope.list(basePath, testsDir, true);
-  return links;
-}
-
-
 //used by tests to determine their directory based off window.location.path
 function getRootDirectory(path, chromeURI) {
   if (chromeURI === undefined)
@@ -313,19 +257,6 @@ function getTestList(params, callback) {
     }
   }
   params = config;
-  if (params.manifestFile) {
-    getTestManifest("http://mochi.test:8888/" + params.manifestFile, params, callback);
-    return;
-  }
-
-  var links = {};
-  // load server.js in so we can share template functions
-  var scriptLoader = Cc["@mozilla.org/moz/jssubscript-loader;1"].
-                       getService(Ci.mozIJSSubScriptLoader);
-  var srvScope = {};
-  scriptLoader.loadSubScript('chrome://mochikit/content/server.js',
-                             srvScope);
-
-  links = getFileListing(baseurl, params.testPath, params.testRoot, srvScope);
-  callback(links);
+  getTestManifest("http://mochi.test:8888/" + params.manifestFile, params, callback);
+  return;
 }
diff --git a/testing/mochitest/jetpack-addon-harness.js b/testing/mochitest/jetpack-addon-harness.js
index 6f9db61ddf4..47f5a157617 100644
--- a/testing/mochitest/jetpack-addon-harness.js
+++ b/testing/mochitest/jetpack-addon-harness.js
@@ -197,7 +197,7 @@ function testInit() {
       function finish() {
         if (passed + failed == 0) {
           dump("TEST-UNEXPECTED-FAIL | jetpack-addon-harness.js | " +
-               "No tests to run. Did you pass an invalid --test-path?\n");
+               "No tests to run. Did you pass invalid test_paths?\n");
         }
         else {
           dump("Jetpack Addon Test Summary\n");
diff --git a/testing/mochitest/jetpack-package-harness.js b/testing/mochitest/jetpack-package-harness.js
index ee93fdeb90e..70867a72313 100644
--- a/testing/mochitest/jetpack-package-harness.js
+++ b/testing/mochitest/jetpack-package-harness.js
@@ -218,7 +218,7 @@ function testInit() {
         function finish() {
           if (passed + failed == 0) {
             dump("TEST-UNEXPECTED-FAIL | jetpack-package-harness.js | " +
-                 "No tests to run. Did you pass an invalid --test-path?\n");
+                 "No tests to run. Did you pass invalid test_paths?\n");
           }
           else {
             dump("Jetpack Package Test Summary\n");
diff --git a/testing/mochitest/mach_commands.py b/testing/mochitest/mach_commands.py
index eedb5970042..8735111101f 100644
--- a/testing/mochitest/mach_commands.py
+++ b/testing/mochitest/mach_commands.py
@@ -236,10 +236,6 @@ class MochitestRunner(MozbuildObject):
         if test_objects:
             return test_objects
 
-        # Ensure test paths are relative to topobjdir or topsrcdir.
-        test_paths = test_paths or []
-        test_paths = [self._wrap_path_argument(tp).relpath() for tp in test_paths]
-
         from mozbuild.testing import TestResolver
         resolver = self._spawn(TestResolver)
         tests = list(resolver.resolve_tests(paths=test_paths, cwd=cwd))
@@ -440,12 +436,7 @@ class MachCommands(MachCommandBase):
                      metavar='{{{}}}'.format(', '.join(CANONICAL_FLAVORS)),
                      choices=SUPPORTED_FLAVORS,
                      help='Only run tests of this flavor.')
-    @CommandArgument('test_paths', nargs='*', metavar='TEST', default=None,
-                     help='Test to run. Can be a single test file or a directory of tests '
-                          '(to run recursively). If omitted, the entire suite is run.')
-    def run_mochitest_general(self, test_paths, flavor=None, test_objects=None,
-                              **kwargs):
-
+    def run_mochitest_general(self, flavor=None, test_objects=None, **kwargs):
         buildapp = None
         for app in SUPPORTED_APPS:
             if is_buildapp_in(app)(self):
@@ -469,19 +460,22 @@ class MachCommands(MachCommandBase):
         driver = self._spawn(BuildDriver)
         driver.install_tests(remove=False)
 
+        test_paths = kwargs['test_paths']
+        kwargs['test_paths'] = []
+
         if test_paths and buildapp == 'b2g':
             # In B2G there is often a 'gecko' directory, though topsrcdir is actually
             # elsewhere. This little hack makes test paths like 'gecko/dom' work, even if
             # GECKO_PATH is set in the .userconfig
             gecko_path = mozpath.abspath(mozpath.join(kwargs['b2gPath'], 'gecko'))
             if gecko_path != self.topsrcdir:
-                old_paths = test_paths[:]
-                test_paths = []
-                for tp in old_paths:
+                new_paths = []
+                for tp in test_paths:
                     if mozpath.abspath(tp).startswith(gecko_path):
-                        test_paths.append(mozpath.relpath(tp, gecko_path))
+                        new_paths.append(mozpath.relpath(tp, gecko_path))
                     else:
-                        test_paths.append(tp)
+                        new_paths.append(tp)
+                test_paths = new_paths
 
         mochitest = self._spawn(MochitestRunner)
         tests = mochitest.resolve_tests(test_paths, test_objects, cwd=self._mach_context.cwd)
@@ -576,14 +570,10 @@ class RobocopCommands(MachCommandBase):
              conditions=[conditions.is_android],
              description='Run a Robocop test.',
              parser=setup_argument_parser)
-    @CommandArgument('test_paths', nargs='*', metavar='TEST', default=None,
-                     help='Test to run. Can be a single Robocop test file (like "testLoad.java") '
-                          ' or a directory of tests '
-                          '(to run recursively). If omitted, the entire Robocop suite is run.')
     @CommandArgument('--serve', default=False, action='store_true',
         help='Run no tests but start the mochi.test web server and launch '
              'Fennec with a test profile.')
-    def run_robocop(self, test_paths, serve=False, **kwargs):
+    def run_robocop(self, serve=False, **kwargs):
         if serve:
             kwargs['autorun'] = False
 
@@ -601,6 +591,9 @@ class RobocopCommands(MachCommandBase):
         driver = self._spawn(BuildDriver)
         driver.install_tests(remove=False)
 
+        test_paths = kwargs['test_paths']
+        kwargs['test_paths'] = []
+
         from mozbuild.testing import TestResolver
         resolver = self._spawn(TestResolver)
         tests = list(resolver.resolve_tests(paths=test_paths, cwd=self._mach_context.cwd,
diff --git a/testing/mochitest/mochitest_options.py b/testing/mochitest/mochitest_options.py
index 0e9487a23d1..28eafc031e4 100644
--- a/testing/mochitest/mochitest_options.py
+++ b/testing/mochitest/mochitest_options.py
@@ -58,6 +58,13 @@ class MochitestArguments(ArgumentContainer):
     LEVEL_STRING = ", ".join(LOG_LEVELS)
 
     args = [
+        [["test_paths"],
+         {"nargs": "*",
+          "metavar": "TEST",
+          "default": [],
+          "help": "Test to run. Can be a single test file or a directory of tests "
+                  "(to run recursively). If omitted, the entire suite is run.",
+          }],
         [["--keep-open"],
          {"action": "store_false",
           "dest": "closeWhenDone",
@@ -158,13 +165,6 @@ class MochitestArguments(ArgumentContainer):
           "default": False,
           "suppress": True,
           }],
-        [["--test-path"],
-         {"dest": "testPath",
-          "default": "",
-          "help": "Run the given test or recursively run the given directory of tests.",
-          # if running from mach, a test_paths arg is exposed instead
-          "suppress": build_obj is not None,
-          }],
         [["--bisect-chunk"],
          {"dest": "bisectChunk",
           "default": None,
@@ -552,6 +552,9 @@ class MochitestArguments(ArgumentContainer):
             options.gmp_path = os.pathsep.join(
                 os.path.join(build_obj.bindir, *p) for p in gmp_modules)
 
+        if options.ipcplugins:
+            options.test_paths.append('dom/plugins/test/mochitest')
+
         if options.totalChunks is not None and options.thisChunk is None:
             parser.error(
                 "thisChunk must be specified when totalChunks is specified")
@@ -728,6 +731,15 @@ class MochitestArguments(ArgumentContainer):
         if mozinfo.isWin:
             options.ignoreMissingLeaks.append("tab")
 
+        # XXX We can't normalize test_paths in the non build_obj case here,
+        # because testRoot depends on the flavor, which is determined by the
+        # mach command and therefore not finalized yet. Conversely, test paths
+        # need to be normalized here for the mach case.
+        if options.test_paths and build_obj:
+            # Normalize test paths so they are relative to test root
+            options.test_paths = [build_obj._wrap_path_argument(p).relpath()
+                for p in options.test_paths]
+
         return options
 
 
diff --git a/testing/mochitest/runtests.py b/testing/mochitest/runtests.py
index 30556124ca6..bce7d649877 100644
--- a/testing/mochitest/runtests.py
+++ b/testing/mochitest/runtests.py
@@ -13,7 +13,6 @@ SCRIPT_DIR = os.path.abspath(os.path.realpath(os.path.dirname(__file__)))
 sys.path.insert(0, SCRIPT_DIR)
 
 from argparse import Namespace
-from urlparse import urlparse
 import ctypes
 import glob
 import json
@@ -51,10 +50,11 @@ from manifestparser.filters import (
     chunk_by_dir,
     chunk_by_runtime,
     chunk_by_slice,
+    pathprefix,
     subsuite,
     tags,
 )
-from mochitest_options import MochitestArgumentParser
+from mochitest_options import MochitestArgumentParser, build_obj
 from mozprofile import Profile, Preferences
 from mozprofile.permissions import ServerLocations
 from urllib import quote_plus as encodeURIComponent
@@ -63,12 +63,6 @@ from mozlog.structured import commandline
 
 here = os.path.abspath(os.path.dirname(__file__))
 
-try:
-    from mozbuild.base import MozbuildObject
-    build_obj = MozbuildObject.from_environment(cwd=here)
-except ImportError:
-    build_obj = None
-
 
 ###########################
 # Option for NSPR logging #
@@ -638,14 +632,14 @@ class MochitestUtilsMixin(object):
                 self.urlOpts.append("runUntilFailure=1")
             if options.repeat:
                 self.urlOpts.append("repeat=%d" % options.repeat)
-            if os.path.isfile(
+            if len(options.test_paths) == 1 and options.repeat > 0 and os.path.isfile(
                 os.path.join(
                     self.oldcwd,
                     os.path.dirname(__file__),
                     self.TEST_PATH,
-                    options.testPath)) and options.repeat > 0:
-                self.urlOpts.append("testname=%s" %
-                                    ("/").join([self.TEST_PATH, options.testPath]))
+                    options.test_paths[0])):
+                self.urlOpts.append("testname=%s" % "/".join(
+                    [self.TEST_PATH, options.test_paths[0]]))
             if options.manifestFile:
                 self.urlOpts.append("manifestFile=%s" % options.manifestFile)
             if options.failureFile:
@@ -716,50 +710,43 @@ class MochitestUtilsMixin(object):
         return (testPattern.match(pathPieces[-1]) and
                 not re.search(r'\^headers\^$', filename))
 
-    def getTestPath(self, options):
-        if options.ipcplugins:
-            return "dom/plugins/test/mochitest"
-        else:
-            return options.testPath
-
     def setTestRoot(self, options):
-        if hasattr(self, "testRoot"):
-            return self.testRoot, self.testRootAbs
-        else:
-            if options.browserChrome:
-                if options.immersiveMode:
-                    self.testRoot = 'metro'
-                else:
-                    self.testRoot = 'browser'
-            elif options.jetpackPackage:
-                self.testRoot = 'jetpack-package'
-            elif options.jetpackAddon:
-                self.testRoot = 'jetpack-addon'
-            elif options.a11y:
-                self.testRoot = 'a11y'
-            elif options.webapprtChrome:
-                self.testRoot = 'webapprtChrome'
-            elif options.webapprtContent:
-                self.testRoot = 'webapprtContent'
-            elif options.chrome:
-                self.testRoot = 'chrome'
+        if options.browserChrome:
+            if options.immersiveMode:
+                self.testRoot = 'metro'
             else:
-                self.testRoot = self.TEST_PATH
-            self.testRootAbs = os.path.join(SCRIPT_DIR, self.testRoot)
+                self.testRoot = 'browser'
+        elif options.jetpackPackage:
+            self.testRoot = 'jetpack-package'
+        elif options.jetpackAddon:
+            self.testRoot = 'jetpack-addon'
+        elif options.a11y:
+            self.testRoot = 'a11y'
+        elif options.webapprtChrome:
+            self.testRoot = 'webapprtChrome'
+        elif options.webapprtContent:
+            self.testRoot = 'webapprtContent'
+        elif options.chrome:
+            self.testRoot = 'chrome'
+        else:
+            self.testRoot = self.TEST_PATH
+        self.testRootAbs = os.path.join(SCRIPT_DIR, self.testRoot)
 
     def buildTestURL(self, options):
         testHost = "http://mochi.test:8888"
-        testPath = self.getTestPath(options)
-        testURL = "/".join([testHost, self.TEST_PATH, testPath])
-        if os.path.isfile(
-            os.path.join(
-                self.oldcwd,
-                os.path.dirname(__file__),
-                self.TEST_PATH,
-                testPath)) and options.repeat > 0:
-            testURL = "/".join([testHost,
-                                self.TEST_PATH,
-                                os.path.dirname(testPath)])
+        testURL = "/".join([testHost, self.TEST_PATH])
+
+        if len(options.test_paths) == 1 :
+            if options.repeat > 0 and os.path.isfile(
+                os.path.join(
+                    self.oldcwd,
+                    os.path.dirname(__file__),
+                    self.TEST_PATH,
+                    options.test_paths[0])):
+                testURL = "/".join([testURL, os.path.dirname(options.test_paths[0])])
+            else:
+                testURL = "/".join([testURL, options.test_paths[0]])
+
         if options.chrome or options.a11y:
             testURL = "/".join([testHost, self.CHROME_PATH])
         elif options.browserChrome or options.jetpackPackage or options.jetpackAddon:
@@ -1698,7 +1685,6 @@ class Mochitest(MochitestUtilsMixin):
                onLaunch=None,
                detectShutdownLeaks=False,
                screenshotOnFail=False,
-               testPath=None,
                bisectChunk=None,
                quiet=False):
         """
@@ -1775,8 +1761,7 @@ class Mochitest(MochitestUtilsMixin):
                     proc,
                     utilityPath,
                     debuggerInfo,
-                    browserProcessId,
-                    testPath)
+                    browserProcessId)
             kp_kwargs = {'kill_on_timeout': False,
                          'cwd': SCRIPT_DIR,
                          'onTimeout': [timeoutHandler]}
@@ -1896,6 +1881,16 @@ class Mochitest(MochitestUtilsMixin):
         return os.path.join(data_dir, '{}-{}.runtimes.json'.format(
             base, flavor))
 
+    def normalize_paths(self, paths):
+        # Normalize test paths so they are relative to test root
+        norm_paths = []
+        for p in paths:
+            abspath = os.path.abspath(os.path.join(self.oldcwd, p))
+            if abspath.startswith(self.testRootAbs):
+                norm_paths.append(os.path.relpath(abspath, self.testRootAbs))
+            else:
+                norm_paths.append(p)
+        return norm_paths
 
     def getActiveTests(self, options, disabled=True):
         """
@@ -1904,87 +1899,73 @@ class Mochitest(MochitestUtilsMixin):
         if self._active_tests:
             return self._active_tests
 
-        self.setTestRoot(options)
         manifest = self.getTestManifest(options)
         if manifest:
             info = mozinfo.info
 
-            # Bug 883858 - return all tests including disabled tests
-            testPath = self.getTestPath(options)
-            testPath = testPath.replace('\\', '/')
-            if testPath.endswith('.html') or \
-               testPath.endswith('.xhtml') or \
-               testPath.endswith('.xul') or \
-               testPath.endswith('.js'):
-                # In the case where we have a single file, we don't want to
-                # filter based on options such as subsuite.
-                tests = manifest.active_tests(
-                    exists=False, disabled=disabled, **info)
-                for test in tests:
-                    if 'disabled' in test:
-                        del test['disabled']
+            # Bug 1089034 - imptest failure expectations are encoded as
+            # test manifests, even though they aren't tests. This gross
+            # hack causes several problems in automation including
+            # throwing off the chunking numbers. Remove them manually
+            # until bug 1089034 is fixed.
+            def remove_imptest_failure_expectations(tests, values):
+                return (t for t in tests
+                        if 'imptests/failures' not in t['path'])
 
-            else:
-                # Bug 1089034 - imptest failure expectations are encoded as
-                # test manifests, even though they aren't tests. This gross
-                # hack causes several problems in automation including
-                # throwing off the chunking numbers. Remove them manually
-                # until bug 1089034 is fixed.
-                def remove_imptest_failure_expectations(tests, values):
-                    return (t for t in tests
-                            if 'imptests/failures' not in t['path'])
+            filters = [
+                remove_imptest_failure_expectations,
+                subsuite(options.subsuite),
+            ]
 
-                filters = [
-                    remove_imptest_failure_expectations,
-                    subsuite(options.subsuite),
-                ]
+            if options.test_tags:
+                filters.append(tags(options.test_tags))
 
-                # Add chunking filters if specified
-                if options.totalChunks:
-                    if options.chunkByRuntime:
-                        runtime_file = self.resolve_runtime_file(options, info)
-                        if not os.path.exists(runtime_file):
-                            self.log.warning("runtime file %s not found; defaulting to chunk-by-dir" %
-                                             runtime_file)
-                            options.chunkByRuntime = None
-                            flavor = self.getTestFlavor(options)
-                            if flavor in ('browser-chrome', 'devtools-chrome'):
-                                # these values match current mozharness configs
-                                options.chunkbyDir = 5
-                            else:
-                                options.chunkByDir = 4
+            if options.test_paths:
+                options.test_paths = self.normalize_paths(options.test_paths)
+                filters.append(pathprefix(options.test_paths))
 
-                    if options.chunkByDir:
-                        filters.append(chunk_by_dir(options.thisChunk,
-                                                    options.totalChunks,
-                                                    options.chunkByDir))
-                    elif options.chunkByRuntime:
-                        with open(runtime_file, 'r') as f:
-                            runtime_data = json.loads(f.read())
-                        runtimes = runtime_data['runtimes']
-                        default = runtime_data['excluded_test_average']
-                        filters.append(
-                            chunk_by_runtime(options.thisChunk,
-                                             options.totalChunks,
-                                             runtimes,
-                                             default_runtime=default))
-                    else:
-                        filters.append(chunk_by_slice(options.thisChunk,
-                                                      options.totalChunks))
+            # Add chunking filters if specified
+            if options.totalChunks:
+                if options.chunkByRuntime:
+                    runtime_file = self.resolve_runtime_file(options, info)
+                    if not os.path.exists(runtime_file):
+                        self.log.warning("runtime file %s not found; defaulting to chunk-by-dir" %
+                                         runtime_file)
+                        options.chunkByRuntime = None
+                        flavor = self.getTestFlavor(options)
+                        if flavor in ('browser-chrome', 'devtools-chrome'):
+                            # these values match current mozharness configs
+                            options.chunkbyDir = 5
+                        else:
+                            options.chunkByDir = 4
 
-                if options.test_tags:
-                    filters.append(tags(options.test_tags))
+                if options.chunkByDir:
+                    filters.append(chunk_by_dir(options.thisChunk,
+                                                options.totalChunks,
+                                                options.chunkByDir))
+                elif options.chunkByRuntime:
+                    with open(runtime_file, 'r') as f:
+                        runtime_data = json.loads(f.read())
+                    runtimes = runtime_data['runtimes']
+                    default = runtime_data['excluded_test_average']
+                    filters.append(
+                        chunk_by_runtime(options.thisChunk,
+                                         options.totalChunks,
+                                         runtimes,
+                                         default_runtime=default))
+                else:
+                    filters.append(chunk_by_slice(options.thisChunk,
+                                                  options.totalChunks))
 
-                tests = manifest.active_tests(
-                    exists=False, disabled=disabled, filters=filters, **info)
+            tests = manifest.active_tests(
+                exists=False, disabled=disabled, filters=filters, **info)
 
-                if len(tests) == 0:
-                    self.log.error("no tests to run using specified "
-                                   "combination of filters: {}".format(
-                                        manifest.fmt_filters()))
+            if len(tests) == 0:
+                self.log.error("no tests to run using specified "
+                               "combination of filters: {}".format(
+                                    manifest.fmt_filters()))
 
         paths = []
-
         for test in tests:
             if len(tests) == 1 and 'disabled' in test:
                 del test['disabled']
@@ -1993,10 +1974,6 @@ class Mochitest(MochitestUtilsMixin):
             assert pathAbs.startswith(self.testRootAbs)
             tp = pathAbs[len(self.testRootAbs):].replace('\\', '/').strip('/')
 
-            # Filter out tests if we are using --test-path
-            if testPath and not tp.startswith(testPath):
-                continue
-
             if not self.isTest(options, tp):
                 self.log.warning(
                     'Warning: %s from manifest %s is not a valid test' %
@@ -2132,11 +2109,7 @@ class Mochitest(MochitestUtilsMixin):
         dirs = self.getDirectories(options)
 
         result = 1  # default value, if no tests are run.
-        inputTestPath = self.getTestPath(options)
         for d in dirs:
-            if inputTestPath and not inputTestPath.startswith(d):
-                continue
-
             print "dir: %s" % d
             tests_in_dir = [t for t in testsToRun if os.path.dirname(t) == d]
 
@@ -2296,7 +2269,6 @@ class Mochitest(MochitestUtilsMixin):
                                      onLaunch=onLaunch,
                                      detectShutdownLeaks=detectShutdownLeaks,
                                      screenshotOnFail=options.screenshotOnFail,
-                                     testPath=options.testPath,
                                      bisectChunk=options.bisectChunk,
                                      quiet=options.quiet
                                      )
@@ -2337,17 +2309,12 @@ class Mochitest(MochitestUtilsMixin):
             proc,
             utilityPath,
             debuggerInfo,
-            browserProcessId,
-            testPath=None):
+            browserProcessId):
         """handle process output timeout"""
         # TODO: bug 913975 : _processOutput should call self.processOutputLine
         # one more time one timeout (I think)
-        if testPath:
-            error_message = "TEST-UNEXPECTED-TIMEOUT | %s | application timed out after %d seconds with no output on %s" % (
-                self.lastTestSeen, int(timeout), testPath)
-        else:
-            error_message = "TEST-UNEXPECTED-TIMEOUT | %s | application timed out after %d seconds with no output" % (
-                self.lastTestSeen, int(timeout))
+        error_message = "TEST-UNEXPECTED-TIMEOUT | %s | application timed out after %d seconds with no output" % (
+            self.lastTestSeen, int(timeout))
 
         self.message_logger.dump_buffered()
         self.message_logger.buffering = False
@@ -2563,7 +2530,6 @@ class Mochitest(MochitestUtilsMixin):
     def makeTestConfig(self, options):
         "Creates a test configuration file for customizing test execution."
         options.logFile = options.logFile.replace("\\", "\\\\")
-        options.testPath = options.testPath.replace("\\", "\\\\")
 
         if "MOZ_HIDE_RESULTS_TABLE" in os.environ and os.environ[
                 "MOZ_HIDE_RESULTS_TABLE"] == "1":
diff --git a/testing/mochitest/runtestsb2g.py b/testing/mochitest/runtestsb2g.py
index 788dcd79f5f..75d89bbd8a5 100644
--- a/testing/mochitest/runtestsb2g.py
+++ b/testing/mochitest/runtestsb2g.py
@@ -121,6 +121,8 @@ class B2GMochitest(MochitestUtilsMixin):
     def run_tests(self, options):
         """ Prepare, configure, run tests and cleanup """
 
+        self.setTestRoot(options)
+
         manifest = self.build_profile(options)
         self.logPreamble(self.getActiveTests(options))
 
diff --git a/testing/mochitest/runtestsremote.py b/testing/mochitest/runtestsremote.py
index 562acfb7844..3ad1b014850 100644
--- a/testing/mochitest/runtestsremote.py
+++ b/testing/mochitest/runtestsremote.py
@@ -547,13 +547,13 @@ def run_test_harness(options):
         if not options.autorun:
             # Force a single loop iteration. The iteration will start Fennec and
             # the httpd server, but not actually run a test.
-            options.testPath = robocop_tests[0]['name']
+            options.test_paths = [robocop_tests[0]['name']]
 
         retVal = None
         # Filtering tests
         active_tests = []
         for test in robocop_tests:
-            if options.testPath and options.testPath != test['name']:
+            if options.test_paths and test['name'] not in options.test_paths:
                 continue
 
             if 'disabled' in test:
diff --git a/testing/mozbase/manifestparser/manifestparser/filters.py b/testing/mozbase/manifestparser/manifestparser/filters.py
index b0d64e37bcc..d24aa5c0768 100644
--- a/testing/mozbase/manifestparser/manifestparser/filters.py
+++ b/testing/mozbase/manifestparser/manifestparser/filters.py
@@ -339,6 +339,34 @@ class tags(InstanceFilter):
                 yield test
 
 
+class pathprefix(InstanceFilter):
+    """
+    Removes tests that don't start with any of the given test paths.
+
+    :param paths: A list of test paths to filter on
+    """
+
+    def __init__(self, paths):
+        InstanceFilter.__init__(self, paths)
+        if isinstance(paths, basestring):
+            paths = [paths]
+        self.paths = paths
+
+    def __call__(self, tests, values):
+        for test in tests:
+            for tp in self.paths:
+                tp = os.path.normpath(tp)
+                if not os.path.normpath(test['relpath']).startswith(tp):
+                    continue
+
+                # any test path that points to a single file will be run no
+                # matter what, even if it's disabled
+                if 'disabled' in test and os.path.normpath(test['relpath']) == tp:
+                    del test['disabled']
+                yield test
+                break
+
+
 # filter container
 
 DEFAULT_FILTERS = (
diff --git a/testing/taskcluster/tasks/tests/b2g_emulator_mochitest_media.yml b/testing/taskcluster/tasks/tests/b2g_emulator_mochitest_media.yml
index 5437721a8f6..8d5b34c76e3 100644
--- a/testing/taskcluster/tasks/tests/b2g_emulator_mochitest_media.yml
+++ b/testing/taskcluster/tasks/tests/b2g_emulator_mochitest_media.yml
@@ -18,10 +18,10 @@ task:
         --config-file ./mozharness_configs/remove_executables.py
         --download-symbols ondemand
         --test-suite mochitest
-        --test-path dom/media/tests/
         --installer-url {{build_url}}
         --test-url {{tests_url}}
         --xre-url https://queue.taskcluster.net/v1/task/wXAHAaxDQpqxoWF1iljJjg/runs/0/artifacts/public/cache/xulrunner-sdk-40.zip
+        dom/media/tests
     artifacts:
       'public/build':
         type: directory
diff --git a/testing/testsuite-targets.mk b/testing/testsuite-targets.mk
index 98f3871aaa6..249c1984f2b 100644
--- a/testing/testsuite-targets.mk
+++ b/testing/testsuite-targets.mk
@@ -3,14 +3,13 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 
-# Shortcut for mochitest* and xpcshell-tests targets,
-# replaces 'EXTRA_TEST_ARGS=--test-path=...'.
+# Shortcut for mochitest* and xpcshell-tests targets
 ifdef TEST_PATH
-TEST_PATH_ARG := --test-path='$(TEST_PATH)'
-IPCPLUGINS_PATH_ARG := --test-path='$(TEST_PATH)'
+TEST_PATH_ARG := '$(TEST_PATH)'
+IPCPLUGINS_PATH_ARG := '$(TEST_PATH)'
 else
 TEST_PATH_ARG :=
-IPCPLUGINS_PATH_ARG := --test-path=dom/plugins/test
+IPCPLUGINS_PATH_ARG := dom/plugins/test
 endif
 
 # include automation-build.mk to get the path to the binary
@@ -33,7 +32,7 @@ RUN_MOCHITEST_B2G_DESKTOP = \
     --log-tbpl=./$@.log \
     --desktop --profile ${GAIA_PROFILE_DIR} \
     --failure-file=$(abspath _tests/testing/mochitest/makefailures.json) \
-    $(TEST_PATH_ARG) $(EXTRA_TEST_ARGS)
+    $(EXTRA_TEST_ARGS) $(TEST_PATH_ARG)
 
 RUN_MOCHITEST = \
   rm -f ./$@.log && \
@@ -41,7 +40,7 @@ RUN_MOCHITEST = \
     --log-tbpl=./$@.log \
     --failure-file=$(abspath _tests/testing/mochitest/makefailures.json) \
     --testing-modules-dir=$(abspath _tests/modules) \
-    $(SYMBOLS_PATH) $(TEST_PATH_ARG) $(EXTRA_TEST_ARGS)
+    $(SYMBOLS_PATH) $(EXTRA_TEST_ARGS) $(TEST_PATH_ARG)
 
 RERUN_MOCHITEST = \
   rm -f ./$@.log && \
@@ -49,7 +48,7 @@ RERUN_MOCHITEST = \
     --log-tbpl=./$@.log \
     --run-only-tests=makefailures.json \
     --testing-modules-dir=$(abspath _tests/modules) \
-    $(SYMBOLS_PATH) $(TEST_PATH_ARG) $(EXTRA_TEST_ARGS)
+    $(SYMBOLS_PATH) $(EXTRA_TEST_ARGS) $(TEST_PATH_ARG)
 
 RUN_MOCHITEST_REMOTE = \
   rm -f ./$@.log && \
@@ -57,7 +56,7 @@ RUN_MOCHITEST_REMOTE = \
     --log-tbpl=./$@.log $(DM_FLAGS) --dm_trans=$(DM_TRANS) \
     --app=$(TEST_PACKAGE_NAME) --deviceIP=${TEST_DEVICE} --xre-path=${MOZ_HOST_BIN} \
     --testing-modules-dir=$(abspath _tests/modules) \
-    $(SYMBOLS_PATH) $(TEST_PATH_ARG) $(EXTRA_TEST_ARGS)
+    $(SYMBOLS_PATH) $(EXTRA_TEST_ARGS) $(TEST_PATH_ARG)
 
 RUN_MOCHITEST_ROBOCOP = \
   rm -f ./$@.log && \
@@ -67,7 +66,7 @@ RUN_MOCHITEST_ROBOCOP = \
     --robocop-ini=_tests/testing/mochitest/robocop.ini \
     --log-tbpl=./$@.log $(DM_FLAGS) --dm_trans=$(DM_TRANS) \
     --app=$(TEST_PACKAGE_NAME) --deviceIP=${TEST_DEVICE} --xre-path=${MOZ_HOST_BIN} \
-    $(SYMBOLS_PATH) $(TEST_PATH_ARG) $(EXTRA_TEST_ARGS)
+    $(SYMBOLS_PATH) $(EXTRA_TEST_ARGS) $(TEST_PATH_ARG)
 
 ifndef NO_FAIL_ON_TEST_ERRORS
 define check_test_error_internal
@@ -162,7 +161,7 @@ ifeq (powerpc,$(TARGET_CPU))
 	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled.ppc.test.plugin=false $(IPCPLUGINS_PATH_ARG)
 endif
 else
-	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled=false --test-path=dom/plugins/test
+	$(RUN_MOCHITEST) --setpref=dom.ipc.plugins.enabled=false dom/plugins/test
 endif
 	$(CHECK_TEST_ERROR)