diff --git a/src/__phutil_library_map__.php b/src/__phutil_library_map__.php
index 5262157a91..62047c89da 100644
--- a/src/__phutil_library_map__.php
+++ b/src/__phutil_library_map__.php
@@ -779,6 +779,7 @@ phutil_register_library_map(array(
     'HeraldTranscriptController' => 'applications/herald/controller/HeraldTranscriptController.php',
     'HeraldTranscriptListController' => 'applications/herald/controller/HeraldTranscriptListController.php',
     'HeraldTranscriptQuery' => 'applications/herald/query/HeraldTranscriptQuery.php',
+    'HeraldTranscriptTestCase' => 'applications/herald/storage/__tests__/HeraldTranscriptTestCase.php',
     'Javelin' => 'infrastructure/javelin/Javelin.php',
     'JavelinReactorExample' => 'applications/uiexample/examples/JavelinReactorExample.php',
     'JavelinUIExample' => 'applications/uiexample/examples/JavelinUIExample.php',
@@ -3211,6 +3212,7 @@ phutil_register_library_map(array(
     'HeraldTranscriptController' => 'HeraldController',
     'HeraldTranscriptListController' => 'HeraldController',
     'HeraldTranscriptQuery' => 'PhabricatorCursorPagedPolicyAwareQuery',
+    'HeraldTranscriptTestCase' => 'PhabricatorTestCase',
     'JavelinReactorExample' => 'PhabricatorUIExample',
     'JavelinUIExample' => 'PhabricatorUIExample',
     'JavelinViewExample' => 'PhabricatorUIExample',
diff --git a/src/applications/herald/storage/__tests__/HeraldTranscriptTestCase.php b/src/applications/herald/storage/__tests__/HeraldTranscriptTestCase.php
new file mode 100644
index 0000000000..799c8b9e34
--- /dev/null
+++ b/src/applications/herald/storage/__tests__/HeraldTranscriptTestCase.php
@@ -0,0 +1,47 @@
+<?php
+
+final class HeraldTranscriptTestCase extends PhabricatorTestCase {
+
+  public function testTranscriptTruncation() {
+    $long_string = str_repeat('x', 1024 * 1024);
+    $short_string = str_repeat('x', 4096)."\n<...>";
+
+    $long_array = array(
+      'a' => $long_string,
+      'b' => $long_string,
+    );
+
+    $mixed_array = array(
+      'a' => 'abc',
+      'b' => 'def',
+      'c' => $long_string,
+    );
+
+    $fields = array(
+      'ls' => $long_string,
+      'la' => $long_array,
+      'ma' => $mixed_array,
+    );
+
+    $truncated_fields = id(new HeraldObjectTranscript())
+      ->setFields($fields)
+      ->getFields();
+
+    $this->assertEqual($short_string, $truncated_fields['ls']);
+
+    $this->assertEqual(
+      array('a', '<...>'),
+      array_keys($truncated_fields['la']));
+    $this->assertEqual(
+      $short_string.'!<...>',
+      implode('!', $truncated_fields['la']));
+
+    $this->assertEqual(
+      array('a', 'b', 'c'),
+      array_keys($truncated_fields['ma']));
+    $this->assertEqual(
+      'abc!def!'.substr($short_string, 6),
+      implode('!', $truncated_fields['ma']));
+
+  }
+}
\ No newline at end of file
diff --git a/src/applications/herald/storage/transcript/HeraldObjectTranscript.php b/src/applications/herald/storage/transcript/HeraldObjectTranscript.php
index 701bb132fd..e63dc7d6b2 100644
--- a/src/applications/herald/storage/transcript/HeraldObjectTranscript.php
+++ b/src/applications/herald/storage/transcript/HeraldObjectTranscript.php
@@ -35,6 +35,10 @@ final class HeraldObjectTranscript {
   }
 
   public function setFields(array $fields) {
+    foreach ($fields as $key => $value) {
+      $fields[$key] = self::truncateValue($value, 4096);
+    }
+
     $this->fields = $fields;
     return $this;
   }
@@ -42,4 +46,30 @@ final class HeraldObjectTranscript {
   public function getFields() {
     return $this->fields;
   }
+
+  private static function truncateValue($value, $length) {
+    if (is_string($value)) {
+      if (strlen($value) <= $length) {
+        return $value;
+      } else {
+        // NOTE: phutil_utf8_shorten() has huge runtime for giant strings.
+        return phutil_utf8ize(substr($value, 0, $length)."\n<...>");
+      }
+    } else if (is_array($value)) {
+      foreach ($value as $key => $v) {
+        if ($length <= 0) {
+          $value['<...>'] = '<...>';
+          unset($value[$key]);
+        } else {
+          $v = self::truncateValue($v, $length);
+          $length -= strlen($v);
+          $value[$key] = $v;
+        }
+      }
+      return $value;
+    } else {
+      return $value;
+    }
+  }
+
 }