diff --git a/tools/add-projects-to-main.py b/tools/add-projects-to-main.py
new file mode 100644
index 0000000000..818f04663b
--- /dev/null
+++ b/tools/add-projects-to-main.py
@@ -0,0 +1,126 @@
+#!/usr/bin/env python
+
+# Copyright 2017 Red Hat, Inc.
+#
+# Licensed under the Apache License, Version 2.0 (the "License"); you may
+# not use this file except in compliance with the License. You may obtain
+# a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
+# WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
+# License for the specific language governing permissions and limitations
+# under the License.
+
+import collections
+
+import ruamel.yaml
+
+
+def get_single_key(var):
+    if isinstance(var, str):
+        return var
+    elif isinstance(var, list):
+        return var[0]
+    return list(var.keys())[0]
+
+
+def get_comment_text(token):
+    if token is None:
+        return ''
+    elif isinstance(token, list):
+        text = ''
+        for subtoken in token:
+            if subtoken:
+                text += get_comment_text(subtoken)
+        return text
+    else:
+        return token.value
+
+
+def add_projects():
+    yaml = ruamel.yaml.YAML()
+    yaml.indent(mapping=2, sequence=4, offset=2)
+    all_projects = yaml.load(open('gerrit/projects.yaml', 'r'))
+    zuul_main = yaml.load(open('zuul/main.yaml', 'r'))
+
+    existing_projects = set()
+    gerrit = None
+    for tenant in zuul_main:
+        if tenant['tenant']['name'] == 'openstack':
+            gerrit = tenant['tenant']['source']['gerrit']
+            break
+
+    # Find the point in the list where we want to add things and save the
+    # comment text from it so that we can re-add it
+    sorted_index = None
+    saved_comment = None
+    for idx, token in gerrit['untrusted-projects'].ca.items.items():
+        text = get_comment_text(token)
+        if text.startswith('# After this point'):
+            sorted_index = idx
+            saved_comment = token
+            break
+
+    # Get the list of things above the marker comment
+    for project_type in ('config-projects', 'untrusted-projects'):
+        for idx, project in enumerate(gerrit[project_type]):
+            if idx == sorted_index:
+                break
+            if isinstance(project, dict):
+                project = get_single_key(project)
+            existing_projects.add(project)
+
+    new_projects = []
+    for project in all_projects:
+        name = project['project']
+        # It's in the file, already - it's taken care of
+        if name in existing_projects:
+            continue
+
+        # Skip or remove retired projects
+        is_retired = name.split('/')[0].endswith('-attic')
+        in_attic = project.get('acl-config', '').endswith('/retired.config')
+        if is_retired or in_attic:
+            if name in gerrit['untrusted-projects']:
+                del gerrit['untrusted-projects'][name]
+            continue
+
+        new_projects.append(name)
+
+    # Pop things off the end of the list until we're down at the length
+    # indicated by the saved index position. We have to do this weirdly
+    # with passing the index to pop because it's not a real list
+    for idx in reversed(range(sorted_index,
+                              len(gerrit['untrusted-projects']))):
+        gerrit['untrusted-projects'].pop(idx)
+
+    # Toss in a sorted just to make sure - the source list should be sorted
+    # but why tempt fate right?
+    gerrit['untrusted-projects'].extend(sorted(new_projects))
+    gerrit['untrusted-projects'].ca.items[sorted_index] = saved_comment
+
+    yaml.dump(zuul_main, open('zuul/main.yaml', 'w'))
+
+    # Strip the extra 2 spaces that ruamel.yaml appends because we told it
+    # to indent an extra 2 spaces. Because the top level entry is a list it
+    # applies that indentation at the top. It doesn't indent the comment lines
+    # extra though, so don't do them.
+    with open('zuul/main.yaml', 'r') as main_in:
+        main_content = main_in.readlines()
+    with open('zuul/main.yaml', 'w') as main_out:
+        for line in main_content:
+            if '#' in line:
+                main_out.write(line)
+            else:
+                main_out.write(line[2:])
+
+
+def main():
+    add_projects()
+
+
+if __name__ == '__main__':
+    main()
diff --git a/tox.ini b/tox.ini
index ca14c5455a..8cb46170ea 100644
--- a/tox.ini
+++ b/tox.ini
@@ -115,3 +115,9 @@ commands = env ELEMENTS_DIR=elements dib-lint
 
 [testenv:nodepool]
 commands = nodepool -c {toxinidir}/nodepool/nodepool.yaml config-validate
+
+[testenv:add-projects-to-main]
+basepython = python3
+deps =
+    ruamel.yaml
+commands = python tools/add-projects-to-main.py