diff --git a/scripts/celerity/install_merge.sh b/scripts/celerity/install_merge.sh
new file mode 100755
index 0000000000..e6d99e3c7c
--- /dev/null
+++ b/scripts/celerity/install_merge.sh
@@ -0,0 +1,9 @@
+#!/bin/sh
+
+echo "src/__celerity_resource_map__.php merge=celerity" \
+  >> `dirname "$0"`/../../.git/info/attributes
+
+git config merge.celerity.name "Celerity Mapper"
+
+git config merge.celerity.driver \
+  '$GIT_DIR/../scripts/celerity_mapper.php $GIT_DIR/../webroot'
diff --git a/src/docs/developer/adding_new_css_and_js.diviner b/src/docs/developer/adding_new_css_and_js.diviner
index 5f583eca63..5bb5f5914f 100644
--- a/src/docs/developer/adding_new_css_and_js.diviner
+++ b/src/docs/developer/adding_new_css_and_js.diviner
@@ -58,6 +58,15 @@ If you've only changed file content things will generally work even if you
 don't, but they might start not working as well in the future if you skip this
 step.
 
+The generated file `src/__celerity_resource_map__.php` causes merge conflicts
+quite often. They can be resolved by running the Celerity mapper. You can
+automate this process by running:
+
+  phabricator/ $ ./scripts/celerity/install_merge.sh
+
+This will install Git merge driver which will run when a conflict in this file
+occurs.
+
 = Including a File =
 
 To include a CSS or JS file in a page, use