diff --git a/readthedocs/doc_builder/backends/sphinx.py b/readthedocs/doc_builder/backends/sphinx.py
index 8a4323fc3ae..d73010ec495 100644
--- a/readthedocs/doc_builder/backends/sphinx.py
+++ b/readthedocs/doc_builder/backends/sphinx.py
@@ -139,6 +139,9 @@ def get_config_params(self):
             'generate_json_artifacts': self.project.has_feature(
                 Feature.BUILD_JSON_ARTIFACTS_WITH_HTML
             ),
+            'dont_overwrite_sphinx_context': self.project.has_feature(
+                Feature.DONT_OVERWRITE_SPHINX_CONTEXT
+            ),
         }
 
         finalize_sphinx_context_data.send(
diff --git a/readthedocs/doc_builder/templates/doc_builder/conf.py.tmpl b/readthedocs/doc_builder/templates/doc_builder/conf.py.tmpl
index d6eb89ecaa8..1eff1d4a69a 100644
--- a/readthedocs/doc_builder/templates/doc_builder/conf.py.tmpl
+++ b/readthedocs/doc_builder/templates/doc_builder/conf.py.tmpl
@@ -128,7 +128,13 @@ context = {
 {% block extra_context %}{% endblock %}
 
 if 'html_context' in globals():
+    {% if dont_overwrite_sphinx_context %}
+    for key in context:
+        if key not in html_context:
+            html_context[key] = context[key]
+    {% else %}
     html_context.update(context)
+    {% endif %}
 else:
     html_context = context
 
diff --git a/readthedocs/projects/models.py b/readthedocs/projects/models.py
index 61155948021..1d278b1f8ba 100644
--- a/readthedocs/projects/models.py
+++ b/readthedocs/projects/models.py
@@ -1021,6 +1021,7 @@ def add_features(sender, **kwargs):
     PIP_ALWAYS_UPGRADE = 'pip_always_upgrade'
     SKIP_SUBMODULES = 'skip_submodules'
     BUILD_JSON_ARTIFACTS_WITH_HTML = 'build_json_artifacts_with_html'
+    DONT_OVERWRITE_SPHINX_CONTEXT = 'dont_overwrite_sphinx_context'
 
     FEATURES = (
         (USE_SPHINX_LATEST, _('Use latest version of Sphinx')),
@@ -1030,6 +1031,8 @@ def add_features(sender, **kwargs):
         (SKIP_SUBMODULES, _('Skip git submodule checkout')),
         (BUILD_JSON_ARTIFACTS_WITH_HTML, _(
             'Build the json artifacts with the html build step')),
+        (DONT_OVERWRITE_SPHINX_CONTEXT, _(
+            'Do not overwrite context vars in conf.py with Read the Docs context',)),
     )
 
     projects = models.ManyToManyField(