--- a/tools/tryselect/tasks.py
+++ b/tools/tryselect/tasks.py
@@ -3,80 +3,125 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 from __future__ import absolute_import, print_function, unicode_literals
 
 import json
 import os
 import sys
 
+import requests
 from mozboot.util import get_state_dir
 from mozbuild.base import MozbuildObject
 from mozpack.files import FileFinder
+from mozversioncontrol import get_repository_object
 
 from taskgraph.generator import TaskGraphGenerator
 from taskgraph.parameters import (
     ParameterMismatch,
     load_parameters_file,
 )
 from taskgraph.taskgraph import TaskGraph
+from taskgraph.util.taskcluster import (
+    get_artifact,
+    find_task_id,
+)
 
 here = os.path.abspath(os.path.dirname(__file__))
 build = MozbuildObject.from_environment(cwd=here)
 
 
 PARAMETER_MISMATCH = """
 ERROR - The parameters being used to generate tasks differ from those defined
 in your working copy:
 
     {}
 
 To fix this, either rebase onto the latest mozilla-central or pass in
 -p/--parameters. For more information on how to define parameters, see:
 https://firefox-source-docs.mozilla.org/taskcluster/taskcluster/mach.html#parameters
 """
 
+PARAMETER_DEFAULT = "project=mozilla-central"
+
 
 def invalidate(cache):
     if not os.path.isfile(cache):
         return
 
     tc_dir = os.path.join(build.topsrcdir, 'taskcluster')
     tmod = max(os.path.getmtime(os.path.join(tc_dir, p)) for p, _ in FileFinder(tc_dir))
     cmod = os.path.getmtime(cache)
 
     if tmod > cmod:
         os.remove(cache)
 
 
-def get_taskgraph(params=None, full=False):
-    params = params or "project=mozilla-central"
-    cache_dir = os.path.join(get_state_dir()[0], 'cache', 'taskgraph')
-    attr = 'full_task_graph' if full else 'target_task_graph'
-    cache = os.path.join(cache_dir, attr)
+def get_taskgraph_from_artifact(attr):
+    vcs = get_repository_object(build.topsrcdir)
+
+    # If files under /taskcluster are modified locally, then any downloaded
+    # taskgraph artifact will be invalid and there's no point in continuing.
+    if any(f.startswith('taskcluster') for f in vcs.get_outgoing_files()):
+        return
+
+    print("downloading {}".format(attr.replace('_', ' ')))
+    index = "gecko.v2.mozilla-central.revision.{}.firefox.decision".format(vcs.base_ref)
+    task_id = find_task_id(index)
 
-    invalidate(cache)
-    if os.path.isfile(cache):
-        with open(cache, 'r') as fh:
-            return TaskGraph.from_json(json.load(fh))[1]
+    step = attr.split('_')[0]
+    try:
+        response = get_artifact(task_id, 'public/{}-task-graph.json'.format(step))
+    except requests.HTTPError as e:
+        print("Bad response: {}.. ".format(e.response.status_code), end="")
+        sys.stdout.flush()
+        return
+    return TaskGraph.from_json(response)[1]
 
-    if not os.path.isdir(cache_dir):
-        os.makedirs(cache_dir)
 
-    print("Task configuration changed, generating {}".format(attr.replace('_', ' ')))
+def get_taskgraph_from_generator(attr, params):
+    print("generating {}".format(attr.replace('_', ' ')))
     try:
         params = load_parameters_file(params, strict=False)
         params.check()
     except ParameterMismatch as e:
         print(PARAMETER_MISMATCH.format(e.args[0]))
         sys.exit(1)
 
     cwd = os.getcwd()
     os.chdir(build.topsrcdir)
 
     root = os.path.join(build.topsrcdir, 'taskcluster', 'ci')
     tg = getattr(TaskGraphGenerator(root_dir=root, parameters=params), attr)
 
     os.chdir(cwd)
+    return tg
+
+
+def get_taskgraph(params=None, full=False):
+    params = params or PARAMETER_DEFAULT
+    cache_dir = os.path.join(get_state_dir()[0], 'cache', 'taskgraph')
+    attr = 'full_task_graph' if full else 'target_task_graph'
+    cache = os.path.join(cache_dir, attr)
+
+    invalidate(cache)
+    if os.path.isfile(cache):
+        with open(cache, 'r') as fh:
+            return TaskGraph.from_json(json.load(fh))[1]
+
+    if not os.path.isdir(cache_dir):
+        os.makedirs(cache_dir)
+
+    # First attempt to download a taskgraph from a mozilla-central decision
+    # task artifact as it is faster. If that fails or if taskcluster was
+    # modified locally, fallback to generating the taskgraph.
+    print("Task configuration changed.. ", end="")
+    sys.stdout.flush()
+    tg = None
+    if params == PARAMETER_DEFAULT:
+        tg = get_taskgraph_from_artifact(attr)
+    if not tg:
+        tg = get_taskgraph_from_generator(attr, params)
 
     with open(cache, 'w') as fh:
         json.dump(tg.to_json(), fh)
+
     return tg