diff --git a/tox.ini b/tox.ini
index 92466fcc..af89ca39 100644
--- a/tox.ini
+++ b/tox.ini
@@ -56,7 +56,7 @@ deps =
   -r{toxinidir}/doc/requirements.txt
 commands =
   rm -fr doc/build
-  sphinx-build -W --keep-going -b html doc/source doc/build/html {posargs}
+  sphinx-build -W --keep-going -b html -j auto doc/source doc/build/html {posargs}
 
 [testenv:mypy]
 commands =
@@ -72,7 +72,7 @@ whitelist_externals =
 deps = {[testenv:docs]deps}
 commands =
   rm -rf releasenotes/build
-  sphinx-build -a -E -W -d releasenotes/build/doctrees --keep-going -b html releasenotes/source releasenotes/build/html
+  sphinx-build -W --keep-going -b html -j auto releasenotes/source releasenotes/build/html {posargs}
 
 [hacking]
 import_exceptions = oslo_config._i18n