diff --git a/taskcluster/scripts/run-task b/taskcluster/scripts/run-task
index 8f4ea64797af..342e9a2b736f 100755
--- a/taskcluster/scripts/run-task
+++ b/taskcluster/scripts/run-task
@@ -92,6 +92,7 @@ or added to the task's docker image then added to the PATH.
 EXIT_PURGE_CACHE = 72
 
 
+IS_MACOSX = sys.platform == 'darwin'
 IS_POSIX = os.name == 'posix'
 IS_WINDOWS = os.name == 'nt'
 
@@ -402,7 +403,9 @@ def vcs_checkout(source_repo, dest, store_path,
         print('revision is not specified for checkout')
         sys.exit(1)
 
-    if IS_POSIX:
+    if IS_MACOSX:
+        hg_bin = '/tools/python27-mercurial/bin/hg'
+    elif IS_POSIX:
         hg_bin = 'hg'
     elif IS_WINDOWS:
         # This is where OCC installs it in the AMIs.
@@ -411,6 +414,7 @@ def vcs_checkout(source_repo, dest, store_path,
             print('could not find Mercurial executable: %s' % hg_bin)
             sys.exit(1)
 
+    store_path = os.path.abspath(store_path)
     args = [
         hg_bin,
         'robustcheckout',
diff --git a/taskcluster/taskgraph/transforms/job/common.py b/taskcluster/taskgraph/transforms/job/common.py
index c01f4cc7bb7a..92393d726d9f 100644
--- a/taskcluster/taskgraph/transforms/job/common.py
+++ b/taskcluster/taskgraph/transforms/job/common.py
@@ -64,12 +64,20 @@ def support_vcs_checkout(config, job, taskdesc, sparse=False):
     This can only be used with ``run-task`` tasks, as the cache name is
     reserved for ``run-task`` tasks.
     """
-    is_win = job['worker']['os'] == 'windows'
+    worker = job['worker']
+    is_mac = worker['os'] == 'macosx'
+    is_win = worker['os'] == 'windows'
+    is_linux = worker['os'] == 'linux'
+    assert is_mac or is_win or is_linux
 
     if is_win:
         checkoutdir = './build'
         geckodir = '{}/src'.format(checkoutdir)
         hgstore = 'y:/hg-shared'
+    elif is_mac:
+        checkoutdir = './checkouts'
+        geckodir = '{}/gecko'.format(checkoutdir)
+        hgstore = '{}/hg-shared'.format(checkoutdir)
     else:
         checkoutdir = '{workdir}/checkouts'.format(**job['run'])
         geckodir = '{}/gecko'.format(checkoutdir)
@@ -78,7 +86,7 @@ def support_vcs_checkout(config, job, taskdesc, sparse=False):
     level = config.params['level']
     # native-engine and generic-worker do not support caches (yet), so we just
     # do a full clone every time :(
-    if job['worker']['implementation'] in ('docker-worker', 'docker-engine'):
+    if worker['implementation'] in ('docker-worker', 'docker-engine'):
         name = 'level-%s-checkouts' % level
 
         # comm-central checkouts need their own cache, because clobber won't
diff --git a/taskcluster/taskgraph/transforms/job/run_task.py b/taskcluster/taskgraph/transforms/job/run_task.py
index 800355414fba..cc87da414a23 100644
--- a/taskcluster/taskgraph/transforms/job/run_task.py
+++ b/taskcluster/taskgraph/transforms/job/run_task.py
@@ -20,7 +20,7 @@ run_task_schema = Schema({
     # tend to hide their caches.  This cache is never added for level-1 jobs.
     Required('cache-dotcache'): bool,
 
-    # if true (the default), perform a checkout in {workdir}/checkouts/gecko
+    # if true (the default), perform a checkout of gecko on the worker
     Required('checkout'): bool,
 
     # The sparse checkout profile to use. Value is the filename relative to the
@@ -41,12 +41,12 @@ run_task_schema = Schema({
 })
 
 
-def common_setup(config, job, taskdesc, command, geckodir):
+def common_setup(config, job, taskdesc, command):
     run = job['run']
     if run['checkout']:
         support_vcs_checkout(config, job, taskdesc,
                              sparse=bool(run['sparse-profile']))
-        command.append('--vcs-checkout={}'.format(geckodir))
+        command.append('--vcs-checkout={}'.format(taskdesc['worker']['env']['GECKO_PATH']))
 
     if run['sparse-profile']:
         command.append('--sparse-profile=build/sparse-profiles/%s' %
@@ -73,8 +73,7 @@ def docker_worker_run_task(config, job, taskdesc):
     run = job['run']
     worker = taskdesc['worker'] = job['worker']
     command = ['/builds/worker/bin/run-task']
-    common_setup(config, job, taskdesc, command,
-                 geckodir='{workdir}/checkouts/gecko'.format(**run))
+    common_setup(config, job, taskdesc, command)
 
     if run.get('cache-dotcache'):
         worker['caches'].append({
@@ -101,8 +100,7 @@ def native_engine_run_task(config, job, taskdesc):
     run = job['run']
     worker = taskdesc['worker'] = job['worker']
     command = ['./run-task']
-    common_setup(config, job, taskdesc, command,
-                 geckodir='{workdir}/checkouts/gecko'.format(**run))
+    common_setup(config, job, taskdesc, command)
 
     worker['context'] = run_task_url(config)
 
@@ -122,15 +120,16 @@ def generic_worker_run_task(config, job, taskdesc):
     run = job['run']
     worker = taskdesc['worker'] = job['worker']
     is_win = worker['os'] == 'windows'
+    is_mac = worker['os'] == 'macosx'
 
     if is_win:
         command = ['C:/mozilla-build/python3/python3.exe', 'run-task']
-        geckodir = './build/src'
+    elif is_mac:
+        command = ['/tools/python36/bin/python3.6', 'run-task']
     else:
         command = ['./run-task']
-        geckodir = '{workdir}/checkouts/gecko'.format(**run)
 
-    common_setup(config, job, taskdesc, command, geckodir=geckodir)
+    common_setup(config, job, taskdesc, command)
 
     worker.setdefault('mounts', [])
     if run.get('cache-dotcache'):