diff --git a/src/repository/hookapi/base/ArcanistHookAPI.php b/src/repository/hookapi/base/ArcanistHookAPI.php
index e79e5e0c..3696dc66 100644
--- a/src/repository/hookapi/base/ArcanistHookAPI.php
+++ b/src/repository/hookapi/base/ArcanistHookAPI.php
@@ -21,4 +21,5 @@
  */
 abstract class ArcanistHookAPI {
   abstract public function getCurrentFileData($path);
+  abstract public function getUpstreamFileData($path);
 }
diff --git a/src/repository/hookapi/subversion/ArcanistSubversionHookAPI.php b/src/repository/hookapi/subversion/ArcanistSubversionHookAPI.php
index ca0255c4..da5d337f 100644
--- a/src/repository/hookapi/subversion/ArcanistSubversionHookAPI.php
+++ b/src/repository/hookapi/subversion/ArcanistSubversionHookAPI.php
@@ -40,4 +40,12 @@ final class ArcanistSubversionHookAPI extends ArcanistHookAPI {
 
     return ($err? null : $file);
   }
+
+  public function getUpstreamFileData($path) {
+    list($err, $file) = exec_manual(
+      'svnlook cat %s %s',
+      $this->repository,
+      $this->root."/$path");
+    return ($err ? null : $file);
+  }
 }