diff --git a/taskcluster/taskgraph/transforms/job/__init__.py b/taskcluster/taskgraph/transforms/job/__init__.py
index 1ccd3d0a3718..6b9466234187 100644
--- a/taskcluster/taskgraph/transforms/job/__init__.py
+++ b/taskcluster/taskgraph/transforms/job/__init__.py
@@ -350,8 +350,8 @@ def make_task_description(config, jobs):
     import_sibling_modules(exceptions=('common.py',))
 
     for job in jobs:
-        # always-optimized tasks never execute, so have no workdir
-        if job['run']['using'] != 'always-optimized':
+        # only docker-worker uses a fixed absolute path to find directories
+        if job['worker']['implementation'] == 'docker-worker':
             job['run'].setdefault('workdir', '/builds/worker')
 
         taskdesc = copy.deepcopy(job)
diff --git a/taskcluster/taskgraph/transforms/job/common.py b/taskcluster/taskgraph/transforms/job/common.py
index 4de97faae077..b2381994a097 100644
--- a/taskcluster/taskgraph/transforms/job/common.py
+++ b/taskcluster/taskgraph/transforms/job/common.py
@@ -82,20 +82,21 @@ def support_vcs_checkout(config, job, taskdesc, sparse=False):
     is_mac = worker['os'] == 'macosx'
     is_win = worker['os'] == 'windows'
     is_linux = worker['os'] == 'linux' or 'linux-bitbar'
+    is_docker = worker['implementation'] == 'docker-worker'
     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:
+    elif is_docker:
         checkoutdir = '{workdir}/checkouts'.format(**job['run'])
         geckodir = '{}/gecko'.format(checkoutdir)
         hgstore = '{}/hg-store'.format(checkoutdir)
+    else:
+        checkoutdir = './checkouts'
+        geckodir = '{}/gecko'.format(checkoutdir)
+        hgstore = '{}/hg-shared'.format(checkoutdir)
 
     cache_name = 'checkouts'
 
diff --git a/taskcluster/taskgraph/transforms/job/hazard.py b/taskcluster/taskgraph/transforms/job/hazard.py
index b1bff519f0de..4e959e934286 100644
--- a/taskcluster/taskgraph/transforms/job/hazard.py
+++ b/taskcluster/taskgraph/transforms/job/hazard.py
@@ -38,7 +38,7 @@ haz_run_schema = Schema({
     Optional('secrets'): Any(bool, [text_type]),
 
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 })
 
 
diff --git a/taskcluster/taskgraph/transforms/job/mach.py b/taskcluster/taskgraph/transforms/job/mach.py
index 64360c3adae4..36267a845335 100644
--- a/taskcluster/taskgraph/transforms/job/mach.py
+++ b/taskcluster/taskgraph/transforms/job/mach.py
@@ -30,7 +30,7 @@ mach_schema = Schema({
     Required('comm-checkout'): bool,
 
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 })
 
 
diff --git a/taskcluster/taskgraph/transforms/job/mozharness.py b/taskcluster/taskgraph/transforms/job/mozharness.py
index fed92de1626c..62fc5702c7ca 100644
--- a/taskcluster/taskgraph/transforms/job/mozharness.py
+++ b/taskcluster/taskgraph/transforms/job/mozharness.py
@@ -116,7 +116,7 @@ mozharness_run_schema = Schema({
     Required('comm-checkout'): bool,
 
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 })
 
 
diff --git a/taskcluster/taskgraph/transforms/job/mozharness_test.py b/taskcluster/taskgraph/transforms/job/mozharness_test.py
index 5c7ea7b5a695..e28698da5864 100644
--- a/taskcluster/taskgraph/transforms/job/mozharness_test.py
+++ b/taskcluster/taskgraph/transforms/job/mozharness_test.py
@@ -10,7 +10,7 @@ import re
 
 import six
 from six import text_type
-from voluptuous import Required
+from voluptuous import Required, Optional
 
 from taskgraph.util.taskcluster import get_artifact_url
 from taskgraph.transforms.job import (
@@ -50,7 +50,7 @@ mozharness_test_run_schema = Schema({
     Required('using'): 'mozharness-test',
     Required('test'): test_description_schema,
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 })
 
 
@@ -215,7 +215,6 @@ def mozharness_test_on_docker(config, job, taskdesc):
 
 @run_job_using('generic-worker', 'mozharness-test', schema=mozharness_test_run_schema)
 def mozharness_test_on_generic_worker(config, job, taskdesc):
-    run = job['run']
     test = taskdesc['run']['test']
     mozharness = test['mozharness']
     worker = taskdesc['worker'] = job['worker']
@@ -406,7 +405,6 @@ def mozharness_test_on_generic_worker(config, job, taskdesc):
         }]
 
     job['run'] = {
-        'workdir': run['workdir'],
         'tooltool-downloads': mozharness['tooltool-downloads'],
         'checkout': test['checkout'],
         'command': mh_command,
diff --git a/taskcluster/taskgraph/transforms/job/python_test.py b/taskcluster/taskgraph/transforms/job/python_test.py
index adde3ba6b059..b84bfa107486 100644
--- a/taskcluster/taskgraph/transforms/job/python_test.py
+++ b/taskcluster/taskgraph/transforms/job/python_test.py
@@ -10,7 +10,7 @@ from __future__ import absolute_import, print_function, unicode_literals
 from six import text_type
 from taskgraph.transforms.job import run_job_using, configure_taskdesc_for_run
 from taskgraph.util.schema import Schema
-from voluptuous import Required
+from voluptuous import Required, Optional
 
 python_test_schema = Schema({
     Required('using'): 'python-test',
@@ -22,7 +22,7 @@ python_test_schema = Schema({
     Required('subsuite'): text_type,
 
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 })
 
 
diff --git a/taskcluster/taskgraph/transforms/job/run_task.py b/taskcluster/taskgraph/transforms/job/run_task.py
index 5a9cd953fbe1..1fea81e2c64f 100644
--- a/taskcluster/taskgraph/transforms/job/run_task.py
+++ b/taskcluster/taskgraph/transforms/job/run_task.py
@@ -54,7 +54,7 @@ run_task_schema = Schema({
     Required('command'): Any([taskref_or_string], taskref_or_string),
 
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 
     # If not false, tooltool downloads will be enabled via relengAPIProxy
     # for either just public files, or all files. Only supported on
diff --git a/taskcluster/taskgraph/transforms/job/spidermonkey.py b/taskcluster/taskgraph/transforms/job/spidermonkey.py
index 8b007e7381e7..310c211941ce 100644
--- a/taskcluster/taskgraph/transforms/job/spidermonkey.py
+++ b/taskcluster/taskgraph/transforms/job/spidermonkey.py
@@ -29,7 +29,7 @@ sm_run_schema = Schema({
     Optional('spidermonkey-platform'): text_type,
 
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 
     Required('tooltool-downloads'): Any(
         False,
diff --git a/taskcluster/taskgraph/transforms/job/toolchain.py b/taskcluster/taskgraph/transforms/job/toolchain.py
index 42ac824a8cb8..abd9b53e099b 100644
--- a/taskcluster/taskgraph/transforms/job/toolchain.py
+++ b/taskcluster/taskgraph/transforms/job/toolchain.py
@@ -68,7 +68,7 @@ toolchain_run_schema = Schema({
     ): text_type,
 
     # Base work directory used to set up the task.
-    Required('workdir'): text_type,
+    Optional('workdir'): text_type,
 })