diff --git a/resources/celerity/map.php b/resources/celerity/map.php
--- a/resources/celerity/map.php
+++ b/resources/celerity/map.php
@@ -10,7 +10,7 @@
     'conpherence.pkg.css' => '3c8a0668',
     'conpherence.pkg.js' => '020aebcf',
     'core.pkg.css' => '2d4810eb',
-    'core.pkg.js' => 'a568e834',
+    'core.pkg.js' => 'c783d8f6',
     'differential.pkg.css' => '8d8360fb',
     'differential.pkg.js' => '67e02996',
     'diffusion.pkg.css' => '42c75c37',
@@ -518,7 +518,7 @@
     'rsrc/js/phuix/PHUIXActionView.js' => 'aaa08f3b',
     'rsrc/js/phuix/PHUIXAutocomplete.js' => '2fbe234d',
     'rsrc/js/phuix/PHUIXButtonView.js' => '55a24e84',
-    'rsrc/js/phuix/PHUIXDropdownMenu.js' => 'bdce4d78',
+    'rsrc/js/phuix/PHUIXDropdownMenu.js' => '7acfd98b',
     'rsrc/js/phuix/PHUIXExample.js' => 'c2c500a7',
     'rsrc/js/phuix/PHUIXFormControl.js' => '38c1f3fb',
     'rsrc/js/phuix/PHUIXIconView.js' => 'a5257c4e',
@@ -874,7 +874,7 @@
     'phuix-action-view' => 'aaa08f3b',
     'phuix-autocomplete' => '2fbe234d',
     'phuix-button-view' => '55a24e84',
-    'phuix-dropdown-menu' => 'bdce4d78',
+    'phuix-dropdown-menu' => '7acfd98b',
     'phuix-form-control-view' => '38c1f3fb',
     'phuix-icon-view' => 'a5257c4e',
     'policy-css' => 'ceb56a08',
@@ -1563,6 +1563,13 @@
       'javelin-install',
       'javelin-dom',
     ),
+    '7acfd98b' => array(
+      'javelin-install',
+      'javelin-util',
+      'javelin-dom',
+      'javelin-vector',
+      'javelin-stratcom',
+    ),
     '7ad020a5' => array(
       'javelin-behavior',
       'javelin-dom',
@@ -1922,13 +1929,6 @@
       'javelin-uri',
       'phabricator-notification',
     ),
-    'bdce4d78' => array(
-      'javelin-install',
-      'javelin-util',
-      'javelin-dom',
-      'javelin-vector',
-      'javelin-stratcom',
-    ),
     'bde53589' => array(
       'phui-inline-comment-view-css',
     ),
diff --git a/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js b/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js
--- a/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js
+++ b/webroot/rsrc/js/phuix/PHUIXDropdownMenu.js
@@ -198,7 +198,35 @@
       var v = JX.$V(this._node);
       var d = JX.Vector.getDim(this._node);
 
-      switch (this.getAlign()) {
+      var alignments = ['right', 'left'];
+      var disallow = {};
+      var margin = 8;
+
+      // If "right" alignment would leave us with the dropdown near or off the
+      // left side of the screen, disallow it.
+      var x_min = ((v.x + d.x) - m.x);
+      if (x_min < margin) {
+        disallow.right = true;
+      }
+
+      var align = this.getAlign();
+
+      // If the position disallows the configured alignment, try the next
+      // best alignment instead.
+
+      // If no alignment is allowed, we'll stick with the original alignment
+      // and accept that it isn't going to render very nicely. This can happen
+      // if the browser window is very, very small.
+      if (align in disallow) {
+        for (var ii = 0; ii < alignments.length; ii++) {
+          if (!(alignments[ii] in disallow)) {
+            align = alignments[ii];
+            break;
+          }
+        }
+      }
+
+      switch (align) {
         case 'right':
           v = v.add(d)
                .add(JX.$V(-m.x, 0));