diff --git a/src/applications/conduit/method/differential/getcommitmessage/ConduitAPI_differential_getcommitmessage_Method.php b/src/applications/conduit/method/differential/getcommitmessage/ConduitAPI_differential_getcommitmessage_Method.php
index 4f3f15ae11..a1ef109a95 100644
--- a/src/applications/conduit/method/differential/getcommitmessage/ConduitAPI_differential_getcommitmessage_Method.php
+++ b/src/applications/conduit/method/differential/getcommitmessage/ConduitAPI_differential_getcommitmessage_Method.php
@@ -1,7 +1,7 @@
 <?php
 
 /*
- * Copyright 2011 Facebook, Inc.
+ * Copyright 2012 Facebook, Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
@@ -29,7 +29,7 @@ class ConduitAPI_differential_getcommitmessage_Method extends ConduitAPIMethod {
     return array(
       'revision_id' => 'optional revision_id',
       'fields' => 'optional dict<string, wild>',
-      'edit' => 'optional bool',
+      'edit' => 'optional enum<"edit", "create">',
     );
   }
 
@@ -58,6 +58,7 @@ class ConduitAPI_differential_getcommitmessage_Method extends ConduitAPIMethod {
     $revision->loadRelationships();
 
     $is_edit = $request->getValue('edit');
+    $is_create = ($is_edit == 'create');
 
     $aux_fields = DifferentialFieldSelector::newSelector()
       ->getFieldSpecifications();
@@ -88,7 +89,8 @@ class ConduitAPI_differential_getcommitmessage_Method extends ConduitAPIMethod {
             "correspond to any configured field.");
         }
 
-        if ($aux_field->shouldOverwriteWhenCommitMessageIsEdited()) {
+        if ($is_create ||
+            $aux_field->shouldOverwriteWhenCommitMessageIsEdited()) {
           $aux_field->setValueFromParsedCommitMessage($value);
         }
       }
diff --git a/src/applications/conduit/method/differential/parsecommitmessage/ConduitAPI_differential_parsecommitmessage_Method.php b/src/applications/conduit/method/differential/parsecommitmessage/ConduitAPI_differential_parsecommitmessage_Method.php
index 02f5ca5f12..547f1922ec 100644
--- a/src/applications/conduit/method/differential/parsecommitmessage/ConduitAPI_differential_parsecommitmessage_Method.php
+++ b/src/applications/conduit/method/differential/parsecommitmessage/ConduitAPI_differential_parsecommitmessage_Method.php
@@ -28,7 +28,8 @@ class ConduitAPI_differential_parsecommitmessage_Method
 
   public function defineParamTypes() {
     return array(
-      'corpus' => 'required string',
+      'corpus'  => 'required string',
+      'partial' => 'optional bool',
     );
   }
 
@@ -43,6 +44,7 @@ class ConduitAPI_differential_parsecommitmessage_Method
 
   protected function execute(ConduitAPIRequest $request) {
     $corpus = $request->getValue('corpus');
+    $is_partial = $request->getValue('partial');
 
     $aux_fields = DifferentialFieldSelector::newSelector()
       ->getFieldSpecifications();
@@ -74,14 +76,16 @@ class ConduitAPI_differential_parsecommitmessage_Method
       }
     }
 
-    foreach ($aux_fields as $field_key => $aux_field) {
-      try {
-        $aux_field->validateField();
-      } catch (DifferentialFieldValidationException $ex) {
-        $field_label = $aux_field->renderLabelForCommitMessage();
-        $errors[] =
-          "Invalid or missing field '{$field_label}': ".
-          $ex->getMessage();
+    if (!$is_partial) {
+      foreach ($aux_fields as $field_key => $aux_field) {
+        try {
+          $aux_field->validateField();
+        } catch (DifferentialFieldValidationException $ex) {
+          $field_label = $aux_field->renderLabelForCommitMessage();
+          $errors[] =
+            "Invalid or missing field '{$field_label}': ".
+            $ex->getMessage();
+        }
       }
     }