diff --git a/Gruntfile.js b/Gruntfile.js
index 32e56cc4cc..8afa3c7767 100644
--- a/Gruntfile.js
+++ b/Gruntfile.js
@@ -11,7 +11,25 @@ module.exports = function(grunt) {
 		BUILD_DIR = 'build/',
  		BANNER_TEXT = '/*! This file is auto-generated */',
 		autoprefixer = require( 'autoprefixer' ),
-		phpUnitWatchGroup = grunt.option( 'group' );
+		phpUnitWatchGroup = grunt.option( 'group' ),
+		buildFiles = [
+			'*.php',
+			'*.txt',
+			'*.html',
+			'wp-includes/**', // Include everything in wp-includes.
+			'wp-admin/**', // Include everything in wp-admin.
+			'wp-content/index.php',
+			'wp-content/themes/index.php',
+			'wp-content/themes/twenty*/**',
+			'wp-content/plugins/index.php',
+			'wp-content/plugins/hello.php',
+			'wp-content/plugins/akismet/**'
+		],
+		cleanFiles = [];
+
+	buildFiles.forEach( function( buildFile ) {
+		cleanFiles.push( BUILD_DIR + buildFile );
+	} );
 
 	if ( 'watch:phpunit' === grunt.cli.tasks[ 0 ] && ! phpUnitWatchGroup ) {
 		grunt.log.writeln();
@@ -82,7 +100,9 @@ module.exports = function(grunt) {
 			}
 		},
 		clean: {
-			all: [BUILD_DIR],
+			plugins: [BUILD_DIR + 'wp-content/plugins'],
+			themes: [BUILD_DIR + 'wp-content/themes'],
+			all: cleanFiles,
 			js: [BUILD_DIR + 'wp-admin/js/', BUILD_DIR + 'wp-includes/js/'],
 			dynamic: {
 				dot: true,
@@ -111,14 +131,13 @@ module.exports = function(grunt) {
 						dot: true,
 						expand: true,
 						cwd: SOURCE_DIR,
-						src: [
-							'**',
+						src: buildFiles.concat( [
 							'!js/**', // JavaScript is extracted into separate copy tasks.
-							'!**/.{svn,git}/**', // Ignore version control directories.
+							'!.{svn,git}', // Exclude version control folders.
 							'!wp-includes/version.php', // Exclude version.php
 							'!index.php', '!wp-admin/index.php',
 							'!_index.php', '!wp-admin/_index.php'
-						],
+						] ),
 						dest: BUILD_DIR
 					},
 					{