diff --git a/roles/run-tempest/README.rst b/roles/run-tempest/README.rst
index 71b8e4f..e1787b6 100644
--- a/roles/run-tempest/README.rst
+++ b/roles/run-tempest/README.rst
@@ -56,3 +56,14 @@
                (?x)    # Ignore comments and whitespaces
                # Line with only a comment.
                (tempest.api.identity).*$
+
+.. zuul:rolevar:: tox_extra_args
+   :default: ''
+
+   String of extra command line options to pass to tox.
+
+   Here is an example of running tox with --sitepackages option:
+
+       ::
+           vars:
+             tox_extra_args: --sitepackages
diff --git a/roles/run-tempest/defaults/main.yaml b/roles/run-tempest/defaults/main.yaml
index c89eb93..06918b5 100644
--- a/roles/run-tempest/defaults/main.yaml
+++ b/roles/run-tempest/defaults/main.yaml
@@ -2,3 +2,4 @@
 tempest_test_regex: ''
 tox_envlist: smoke
 tempest_black_regex: ''
+tox_extra_args: ''
diff --git a/roles/run-tempest/tasks/main.yaml b/roles/run-tempest/tasks/main.yaml
index 54ddc71..16086aa 100644
--- a/roles/run-tempest/tasks/main.yaml
+++ b/roles/run-tempest/tasks/main.yaml
@@ -35,7 +35,7 @@
       when: blacklist_stat.stat.exists
 
 - name: Run Tempest
-  command: tox -e {{tox_envlist}} -- {{tempest_test_regex|quote}} {{blacklist_option|default('')}} \
+  command: tox -e {{tox_envlist}} {{tox_extra_args}} -- {{tempest_test_regex|quote}} {{blacklist_option|default('')}} \
             --concurrency={{tempest_concurrency|default(default_concurrency)}} \
             --black-regex={{tempest_black_regex|quote}}
   args: