diff --git a/docs/manifest-format.txt b/docs/manifest-format.txt
index 0e6cbe3..56bdf14 100644
--- a/docs/manifest-format.txt
+++ b/docs/manifest-format.txt
@@ -86,6 +86,7 @@
     <!ATTLIST extend-project name CDATA #REQUIRED>
     <!ATTLIST extend-project path CDATA #IMPLIED>
     <!ATTLIST extend-project groups CDATA #IMPLIED>
+    <!ATTLIST extend-project revision CDATA #IMPLIED>
 
     <!ELEMENT remove-project EMPTY>
     <!ATTLIST remove-project name  CDATA #REQUIRED>
@@ -300,6 +301,9 @@
 Attribute `groups`: List of additional groups to which this project
 belongs.  Same syntax as the corresponding element of `project`.
 
+Attribute `revision`: If specified, overrides the revision of the original
+project.  Same syntax as the corresponding element of `project`.
+
 Element annotation
 ------------------
 
diff --git a/manifest_xml.py b/manifest_xml.py
index 0654222..60d6116 100644
--- a/manifest_xml.py
+++ b/manifest_xml.py
@@ -571,12 +571,15 @@
         groups = node.getAttribute('groups')
         if groups:
           groups = self._ParseGroups(groups)
+        revision = node.getAttribute('revision')
 
         for p in self._projects[name]:
           if path and p.relpath != path:
             continue
           if groups:
             p.groups.extend(groups)
+          if revision:
+            p.revisionExpr = revision
       if node.nodeName == 'repo-hooks':
         # Get the name of the project and the (space-separated) list of enabled.
         repo_hooks_project = self._reqatt(node, 'in-project')