diff --git a/scripts/phutil_rebuild_map.php b/scripts/phutil_rebuild_map.php
--- a/scripts/phutil_rebuild_map.php
+++ b/scripts/phutil_rebuild_map.php
@@ -61,18 +61,16 @@
 }
 
 if ($args->getArg('show')) {
-  $builder->setDryRun(true);
-}
-
-$library_map = $builder->buildMap();
+  $library_map = $builder->buildMap();
 
-if ($args->getArg('show')) {
   if ($args->getArg('ugly')) {
     echo json_encode($library_map);
   } else {
     $json = new PhutilJSON();
     echo $json->encodeFormatted($library_map);
   }
+} else {
+  $builder->buildAndWriteMap();
 }
 
 exit(0);
diff --git a/src/__tests__/PhutilInfrastructureTestCase.php b/src/__tests__/PhutilInfrastructureTestCase.php
--- a/src/__tests__/PhutilInfrastructureTestCase.php
+++ b/src/__tests__/PhutilInfrastructureTestCase.php
@@ -21,8 +21,6 @@
     $root = phutil_get_library_root($library);
 
     $new_library_map = id(new PhutilLibraryMapBuilder($root))
-      ->setQuiet(true)
-      ->setDryRun(true)
       ->buildMap();
 
     $bootloader = PhutilBootloader::getInstance();
diff --git a/src/moduleutils/PhutilLibraryMapBuilder.php b/src/moduleutils/PhutilLibraryMapBuilder.php
--- a/src/moduleutils/PhutilLibraryMapBuilder.php
+++ b/src/moduleutils/PhutilLibraryMapBuilder.php
@@ -14,7 +14,6 @@
   private $root;
   private $quiet = true;
   private $subprocessLimit = 8;
-  private $dryRun = false;
 
   const LIBRARY_MAP_VERSION_KEY   = '__library_version__';
   const LIBRARY_MAP_VERSION       = 2;
@@ -63,21 +62,7 @@
   }
 
   /**
-   * Control whether the map should be rebuilt, or just shown (printed to
-   * stdout in JSON).
-   *
-   * @param  bool  If true, show map instead of updating.
-   * @return this
-   *
-   * @task map
-   */
-  public function setDryRun($dry_run) {
-    $this->dryRun = $dry_run;
-    return $this;
-  }
-
-  /**
-   * Build or rebuild the library map.
+   * Build the library map.
    *
    * @return dict
    *
@@ -94,7 +79,6 @@
     $this->log("Loading symbol cache...\n");
     $symbol_cache = $this->loadSymbolCache();
 
-
     // Build out the symbol analysis for all the files in the library. For
     // each file, check if it's in cache. If we miss in the cache, do a fresh
     // analysis.
@@ -148,15 +132,19 @@
 
     // Our map is up to date, so either show it on stdout or write it to disk.
     $this->log("Building library map...\n");
-    $library_map = $this->buildLibraryMap($symbol_map);
+    return $this->buildLibraryMap($symbol_map);
+  }
 
-    if (!$this->dryRun) {
-      $this->log("Writing map...\n");
-      $this->writeLibraryMap($library_map);
-    }
+  /**
+   * Build and update the library map.
+   *
+   * @task map
+   */
+  public function buildAndWriteMap() {
+    $library_map = $this->buildMap();
 
-    $this->log("Done.\n");
-    return $library_map;
+    $this->log("Writing map...\n");
+    $this->writeLibraryMap($library_map);
   }
 
   /**