Index: src/applications/differential/controller/DifferentialRevisionViewController.php
===================================================================
--- src/applications/differential/controller/DifferentialRevisionViewController.php
+++ src/applications/differential/controller/DifferentialRevisionViewController.php
@@ -260,6 +260,8 @@
 
     $comment_view = $this->buildTransactions(
       $revision,
+      $diff_vs ? $diffs[$diff_vs] : $target,
+      $target,
       $all_changesets);
 
     $wrap_id = celerity_generate_unique_node_id();
@@ -931,6 +933,8 @@
 
   private function buildTransactions(
     DifferentialRevision $revision,
+    DifferentialDiff $left_diff,
+    DifferentialDiff $right_diff,
     array $changesets) {
     $viewer = $this->getRequest()->getUser();
 
@@ -947,6 +951,9 @@
       ->setUser($viewer)
       ->setObjectPHID($revision->getPHID())
       ->setChangesets($changesets)
+      ->setRevision($revision)
+      ->setLeftDiff($left_diff)
+      ->setRightDiff($right_diff)
       ->setTransactions($xactions);
 
     // TODO: Make this work and restore edit links. We need to copy
Index: src/applications/differential/editor/DifferentialRevisionEditor.php
===================================================================
--- src/applications/differential/editor/DifferentialRevisionEditor.php
+++ src/applications/differential/editor/DifferentialRevisionEditor.php
@@ -701,10 +701,18 @@
     $template = id(new DifferentialComment())
       ->setAuthorPHID($this->getActorPHID())
       ->setRevision($this->revision);
+
     if ($this->contentSource) {
-      $template->setContentSource($this->contentSource);
+      $content_source = $this->contentSource;
+    } else {
+      $content_source = PhabricatorContentSource::newForSource(
+        PhabricatorContentSource::SOURCE_LEGACY,
+        array());
     }
 
+    $template->setContentSource($content_source);
+
+
     // Write the "update active diff" transaction.
     id(clone $template)
       ->setAction(DifferentialAction::ACTION_UPDATE)
Index: src/applications/differential/view/DifferentialTransactionView.php
===================================================================
--- src/applications/differential/view/DifferentialTransactionView.php
+++ src/applications/differential/view/DifferentialTransactionView.php
@@ -4,6 +4,36 @@
   extends PhabricatorApplicationTransactionView {
 
   private $changesets;
+  private $revision;
+  private $rightDiff;
+  private $leftDiff;
+
+  public function setLeftDiff(DifferentialDiff $left_diff) {
+    $this->leftDiff = $left_diff;
+    return $this;
+  }
+
+  public function getLeftDiff() {
+    return $this->leftDiff;
+  }
+
+  public function setRightDiff(DifferentialDiff $right_diff) {
+    $this->rightDiff = $right_diff;
+    return $this;
+  }
+
+  public function getRightDiff() {
+    return $this->rightDiff;
+  }
+
+  public function setRevision(DifferentialRevision $revision) {
+    $this->revision = $revision;
+    return $this;
+  }
+
+  public function getRevision() {
+    return $this->revision;
+  }
 
   public function setChangesets(array $changesets) {
     assert_instances_of($changesets, 'DifferentialChangeset');
@@ -100,8 +130,8 @@
         $by_line = array();
         foreach ($group as $inline) {
           $by_line[] = array(
-            'line' => $inline->getComment()->getLineNumber().','.
-                      $inline->getComment()->getLineLength(),
+            'line' => ((int)$inline->getComment()->getLineNumber() << 16) +
+                      ((int)$inline->getComment()->getLineLength()),
             'inline' => $inline,
           );
         }
@@ -119,7 +149,31 @@
             'content' => parent::renderTransactionContent($inline),
           );
 
-          // TODO: Fix the where/href stuff for nonlocal inlines.
+          $changeset_diff_id = $changeset->getDiffID();
+          if ($comment->getIsNewFile()) {
+            $visible_diff_id = $this->getRightDiff()->getID();
+          } else {
+            $visible_diff_id = $this->getLeftDiff()->getID();
+          }
+
+          // TODO: We still get one edge case wrong here, when we have a
+          // versus diff and the file didn't exist in the old version. The
+          // comment is visible because we show the left side of the target
+          // diff when there's no corresponding file in the versus diff, but
+          // we incorrectly link it off-page.
+
+          $is_visible = ($changeset_diff_id == $visible_diff_id);
+          if (!$is_visible) {
+            $item['where'] = pht('(On Diff #%d)', $changeset_diff_id);
+
+            $revision_id = $this->getRevision()->getID();
+            $comment_id = $comment->getID();
+
+            $item['href'] =
+              "/D".$revision_id.
+              "?id=".$changeset_diff_id.
+              "#inline-".$comment_id;
+          }
 
           $items[] = $item;
         }