diff --git a/src/parser/xhpast/bin/xhpast_parse.php b/src/parser/xhpast/bin/xhpast_parse.php
--- a/src/parser/xhpast/bin/xhpast_parse.php
+++ b/src/parser/xhpast/bin/xhpast_parse.php
@@ -54,10 +54,24 @@
  */
 function xhpast_get_parser_future($data) {
   if (!xhpast_is_available()) {
-    throw new Exception(xhpast_get_build_instructions());
+    try {
+      // Try to build XHPAST automatically. If we can't then just ask the user
+      // to build it themselves.
+      xhpast_build();
+    } catch (CommandException $e) {
+      throw new Exception(xhpast_get_build_instructions());
+    }
   }
   $future = new ExecFuture('%s', xhpast_get_binary_path());
   $future->write($data);
 
   return $future;
 }
+
+/**
+ * @group xhpast
+ */
+function xhpast_build() {
+  $root = phutil_get_library_root('phutil');
+  execx('%s', $root.'/../scripts/build_xhpast.sh');
+}