--- a/taskcluster/taskgraph/actions/registry.py
+++ b/taskcluster/taskgraph/actions/registry.py
@@ -8,17 +8,17 @@ from __future__ import absolute_import, 
 
 import json
 import os
 import re
 import yaml
 from slugid import nice as slugid
 from types import FunctionType
 from collections import namedtuple
-from taskgraph import create, GECKO
+from taskgraph import create
 from taskgraph.config import load_graph_config
 from taskgraph.util import taskcluster
 from taskgraph.parameters import Parameters
 
 
 actions = []
 callbacks = {}
 
@@ -182,22 +182,17 @@ def register_callback_action(name, title
             match = re.match(r'https://(hg.mozilla.org)/(.*?)/?$', parameters[repo_param])
             if not match:
                 raise Exception('Unrecognized {}'.format(repo_param))
             repo_scope = 'assume:repo:{}/{}:branch:default'.format(
                 match.group(1), match.group(2))
 
             task_group_id = os.environ.get('TASK_ID', slugid())
 
-            # FIXME: https://bugzilla.mozilla.org/show_bug.cgi?id=1454034
-            # trust-domain works, but isn't semantically correct here.
-            if graph_config['trust-domain'] == 'comm':
-                template = os.path.join(GECKO, 'comm', '.taskcluster.yml')
-            else:
-                template = os.path.join(GECKO, '.taskcluster.yml')
+            template = graph_config.taskcluster_yml
 
             with open(template, 'r') as f:
                 taskcluster_yml = yaml.safe_load(f)
                 if taskcluster_yml['version'] != 1:
                     raise Exception('actions.json must be updated to work with .taskcluster.yml')
                 if not isinstance(taskcluster_yml['tasks'], list):
                     raise Exception('.taskcluster.yml "tasks" must be a list for action tasks')
 

--- a/taskcluster/taskgraph/config.py
+++ b/taskcluster/taskgraph/config.py
@@ -3,16 +3,17 @@
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
 from __future__ import absolute_import, print_function, unicode_literals
 
 import os
 import logging
 import attr
 import yaml
+from mozpack import path
 
 from .util.schema import validate_schema, Schema
 from voluptuous import Required, Optional
 
 logger = logging.getLogger(__name__)
 
 graph_config_schema = Schema({
     # The trust-domain for this graph.
@@ -64,16 +65,28 @@ graph_config_schema = Schema({
 @attr.s(frozen=True)
 class GraphConfig(object):
     _config = attr.ib()
     root_dir = attr.ib()
 
     def __getitem__(self, name):
         return self._config[name]
 
+    @property
+    def taskcluster_yml(self):
+        if path.split(self.root_dir)[-2:] != ['taskcluster', 'ci']:
+            raise Exception(
+                "Not guessing path to `.taskcluster.yml`. "
+                "Graph config in non-standard location."
+            )
+        return os.path.join(
+            os.path.dirname(os.path.dirname(self.root_dir)),
+            ".taskcluster.yml",
+        )
+
 
 def validate_graph_config(config):
     return validate_schema(graph_config_schema, config, "Invalid graph configuration:")
 
 
 def load_graph_config(root_dir):
     config_yml = os.path.join(root_dir, "config.yml")
     if not os.path.exists(config_yml):