diff --git a/.gitignore b/.gitignore
index 8cb18f4d7b..948c11f00e 100644
--- a/.gitignore
+++ b/.gitignore
@@ -7,6 +7,8 @@ wp-tests-config.php
 
 # Files and folders related to build/test tools
 /phpunit.xml
+/.phpcs.xml
+/phpcs.xml
 /tests/phpunit/data/plugins/wordpress-importer
 /tests/phpunit/data/.trac-ticket-cache*
 /tests/qunit/compiled.html
diff --git a/composer.json b/composer.json
new file mode 100644
index 0000000000..3c9e021d66
--- /dev/null
+++ b/composer.json
@@ -0,0 +1,20 @@
+{
+	"name": "wordpress/wordpress",
+	"license": "GPL-2.0-or-later",
+	"description": "WordPress is open source software you can use to create a beautiful website, blog, or app.",
+	"homepage": "https://wordpress.org",
+	"keywords": [
+		"blog", "cms", "wordpress", "wp"
+	],
+	"support": {
+		"issues": "https://core.trac.wordpress.org/"
+	},
+	"require-dev": {
+		"dealerdirect/phpcodesniffer-composer-installer": "~0.4.4",
+		"wp-coding-standards/wpcs": "~1.0.0"
+	},
+	"scripts": {
+		"format": "phpcbf --standard=phpcs.xml.dist --report-summary --report-source",
+		"lint": "phpcs --standard=phpcs.xml.dist --report-summary --report-source"
+	}
+}
diff --git a/composer.lock b/composer.lock
new file mode 100644
index 0000000000..73fe1cd7dc
--- /dev/null
+++ b/composer.lock
@@ -0,0 +1,180 @@
+{
+    "_readme": [
+        "This file locks the dependencies of your project to a known state",
+        "Read more about it at https://getcomposer.org/doc/01-basic-usage.md#installing-dependencies",
+        "This file is @generated automatically"
+    ],
+    "content-hash": "525cadb533bc92cc922d79144b33b14a",
+    "packages": [],
+    "packages-dev": [
+        {
+            "name": "dealerdirect/phpcodesniffer-composer-installer",
+            "version": "v0.4.4",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/Dealerdirect/phpcodesniffer-composer-installer.git",
+                "reference": "2e41850d5f7797cbb1af7b030d245b3b24e63a08"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/Dealerdirect/phpcodesniffer-composer-installer/zipball/2e41850d5f7797cbb1af7b030d245b3b24e63a08",
+                "reference": "2e41850d5f7797cbb1af7b030d245b3b24e63a08",
+                "shasum": ""
+            },
+            "require": {
+                "composer-plugin-api": "^1.0",
+                "php": "^5.3|^7",
+                "squizlabs/php_codesniffer": "*"
+            },
+            "require-dev": {
+                "composer/composer": "*",
+                "wimg/php-compatibility": "^8.0"
+            },
+            "suggest": {
+                "dealerdirect/qa-tools": "All the PHP QA tools you'll need"
+            },
+            "type": "composer-plugin",
+            "extra": {
+                "class": "Dealerdirect\\Composer\\Plugin\\Installers\\PHPCodeSniffer\\Plugin"
+            },
+            "autoload": {
+                "psr-4": {
+                    "Dealerdirect\\Composer\\Plugin\\Installers\\PHPCodeSniffer\\": "src/"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Franck Nijhof",
+                    "email": "f.nijhof@dealerdirect.nl",
+                    "homepage": "http://workingatdealerdirect.eu",
+                    "role": "Developer"
+                }
+            ],
+            "description": "PHP_CodeSniffer Standards Composer Installer Plugin",
+            "homepage": "http://workingatdealerdirect.eu",
+            "keywords": [
+                "PHPCodeSniffer",
+                "PHP_CodeSniffer",
+                "code quality",
+                "codesniffer",
+                "composer",
+                "installer",
+                "phpcs",
+                "plugin",
+                "qa",
+                "quality",
+                "standard",
+                "standards",
+                "style guide",
+                "stylecheck",
+                "tests"
+            ],
+            "time": "2017-12-06T16:27:17+00:00"
+        },
+        {
+            "name": "squizlabs/php_codesniffer",
+            "version": "3.3.2",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/squizlabs/PHP_CodeSniffer.git",
+                "reference": "6ad28354c04b364c3c71a34e4a18b629cc3b231e"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/squizlabs/PHP_CodeSniffer/zipball/6ad28354c04b364c3c71a34e4a18b629cc3b231e",
+                "reference": "6ad28354c04b364c3c71a34e4a18b629cc3b231e",
+                "shasum": ""
+            },
+            "require": {
+                "ext-simplexml": "*",
+                "ext-tokenizer": "*",
+                "ext-xmlwriter": "*",
+                "php": ">=5.4.0"
+            },
+            "require-dev": {
+                "phpunit/phpunit": "^4.0 || ^5.0 || ^6.0 || ^7.0"
+            },
+            "bin": [
+                "bin/phpcs",
+                "bin/phpcbf"
+            ],
+            "type": "library",
+            "extra": {
+                "branch-alias": {
+                    "dev-master": "3.x-dev"
+                }
+            },
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "BSD-3-Clause"
+            ],
+            "authors": [
+                {
+                    "name": "Greg Sherwood",
+                    "role": "lead"
+                }
+            ],
+            "description": "PHP_CodeSniffer tokenizes PHP, JavaScript and CSS files and detects violations of a defined set of coding standards.",
+            "homepage": "http://www.squizlabs.com/php-codesniffer",
+            "keywords": [
+                "phpcs",
+                "standards"
+            ],
+            "time": "2018-09-23T23:08:17+00:00"
+        },
+        {
+            "name": "wp-coding-standards/wpcs",
+            "version": "1.0.0",
+            "source": {
+                "type": "git",
+                "url": "https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards.git",
+                "reference": "539c6d74e6207daa22b7ea754d6f103e9abb2755"
+            },
+            "dist": {
+                "type": "zip",
+                "url": "https://api.github.com/repos/WordPress-Coding-Standards/WordPress-Coding-Standards/zipball/539c6d74e6207daa22b7ea754d6f103e9abb2755",
+                "reference": "539c6d74e6207daa22b7ea754d6f103e9abb2755",
+                "shasum": ""
+            },
+            "require": {
+                "php": ">=5.3",
+                "squizlabs/php_codesniffer": "^2.9.0 || ^3.0.2"
+            },
+            "require-dev": {
+                "phpcompatibility/php-compatibility": "*"
+            },
+            "suggest": {
+                "dealerdirect/phpcodesniffer-composer-installer": "^0.4.3 || This Composer plugin will sort out the PHPCS 'installed_paths' automatically."
+            },
+            "type": "phpcodesniffer-standard",
+            "notification-url": "https://packagist.org/downloads/",
+            "license": [
+                "MIT"
+            ],
+            "authors": [
+                {
+                    "name": "Contributors",
+                    "homepage": "https://github.com/WordPress-Coding-Standards/WordPress-Coding-Standards/graphs/contributors"
+                }
+            ],
+            "description": "PHP_CodeSniffer rules (sniffs) to enforce WordPress coding conventions",
+            "keywords": [
+                "phpcs",
+                "standards",
+                "wordpress"
+            ],
+            "time": "2018-07-25T18:10:35+00:00"
+        }
+    ],
+    "aliases": [],
+    "minimum-stability": "stable",
+    "stability-flags": [],
+    "prefer-stable": false,
+    "prefer-lowest": false,
+    "platform": [],
+    "platform-dev": []
+}
diff --git a/phpcs.xml.dist b/phpcs.xml.dist
new file mode 100644
index 0000000000..1bd55b6f4c
--- /dev/null
+++ b/phpcs.xml.dist
@@ -0,0 +1,122 @@
+<?xml version="1.0"?>
+<ruleset name="WordPress Coding Standards">
+	<description>Apply WordPress Coding Standards to all Core files</description>
+
+	<rule ref="WordPress-Core"/>
+	<rule ref="WordPress.CodeAnalysis.EmptyStatement"/>
+
+	<rule ref="PEAR.Functions.FunctionCallSignature">
+		<properties>
+			<property name="allowMultipleArguments" value="false"/>
+		</properties>
+	</rule>
+
+	<arg name="extensions" value="php"/>
+
+	<!-- Strip the filepaths down to the relevant bit. -->
+	<arg name="basepath" value="./"/>
+
+	<!-- Check up to 20 files simultanously. -->
+	<arg name="parallel" value="20"/>
+
+	<!-- Show sniff codes in all reports -->
+	<arg value="ps"/>
+
+	<file>.</file>
+
+	<!-- Exclude the build folder in the current directory, as Travis puts the checkout in a build directory. -->
+	<exclude-pattern type="relative">^build/*</exclude-pattern>
+
+	<!-- Directories and third party library exclusions -->
+	<exclude-pattern>/node_modules/*</exclude-pattern>
+	<exclude-pattern>/vendor/*</exclude-pattern>
+
+	<exclude-pattern>/src/wp-admin/includes/class-ftp*</exclude-pattern>
+	<exclude-pattern>/src/wp-admin/includes/class-pclzip\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-admin/includes/deprecated\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-admin/includes/ms-deprecated\.php</exclude-pattern>
+
+	<exclude-pattern>/src/wp-includes/atomlib\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-IXR\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-json\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-phpass\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-phpmailer\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-pop3\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-requests\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-simplepie\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-smtp\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/class-snoopy\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/deprecated\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/ms-deprecated\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/pluggable-deprecated\.php</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/rss\.php</exclude-pattern>
+
+	<exclude-pattern>/src/wp-includes/ID3/*</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/IXR/*</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/random_compat/*</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/Requests/*</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/SimplePie/*</exclude-pattern>
+	<exclude-pattern>/src/wp-includes/Text/*</exclude-pattern>
+
+	<!-- Test data and fixtures -->
+	<exclude-pattern>/tests/phpunit/build*</exclude-pattern>
+	<exclude-pattern>/tests/phpunit/data/*</exclude-pattern>
+
+	<exclude-pattern>/tools/*</exclude-pattern>
+
+	<!-- Whitelist the WP DB Class and related tests for usage of direct database access functions. -->
+	<rule ref="WordPress.DB.RestrictedFunctions">
+		<exclude-pattern>/src/wp-includes/wp-db\.php</exclude-pattern>
+		<exclude-pattern>/tests/phpunit/tests/db/charset\.php</exclude-pattern>
+	</rule>
+
+	<!-- Whitelist the WP DB related tests for issues with prepared SQL placeholders
+		 (as the handling of those are being tested). -->
+	<rule ref="WordPress.DB.PreparedSQLPlaceholders.UnfinishedPrepare">
+		<exclude-pattern>/tests/phpunit/tests/db\.php</exclude-pattern>
+	</rule>
+	<rule ref="WordPress.DB.PreparedSQLPlaceholders.UnsupportedPlaceholder">
+		<exclude-pattern>/tests/phpunit/tests/db\.php</exclude-pattern>
+	</rule>
+	<rule ref="WordPress.DB.PreparedSQLPlaceholders.UnescapedLiteral">
+		<exclude-pattern>/tests/phpunit/tests/db\.php</exclude-pattern>
+	</rule>
+	<rule ref="WordPress.DB.PreparedSQL.NotPrepared">
+		<exclude-pattern>/tests/phpunit/tests/admin/includesSchema\.php</exclude-pattern>
+		<exclude-pattern>/tests/phpunit/tests/multisite/site\.php</exclude-pattern>
+	</rule>
+
+	<!-- Whitelist the I18n functions file from issues identified by the I18n sniff
+		(such as calling the low-level translate() function). -->
+	<rule ref="WordPress.WP.I18n">
+		<exclude-pattern>/src/wp-includes/l10n\.php</exclude-pattern>
+	</rule>
+
+	<rule ref="Generic.Functions.FunctionCallArgumentSpacing">
+		<exclude-pattern>/wp-config\.php</exclude-pattern>
+		<exclude-pattern>/wp-config-sample\.php</exclude-pattern>
+		<exclude-pattern>/wp-tests-config\.php</exclude-pattern>
+		<exclude-pattern>/wp-tests-config-sample\.php</exclude-pattern>
+	</rule>
+
+	<rule ref="Generic.Files.LineEndings">
+		<exclude-pattern>/wp-config\.php</exclude-pattern>
+		<exclude-pattern>/wp-config-sample\.php</exclude-pattern>
+	</rule>
+
+	<!-- Whitelist test classes for select sniffs. -->
+	<rule ref="WordPress.Files.FileName">
+		<properties>
+			<property name="custom_test_class_whitelist" type="array" value="WP_UnitTestCase,WP_Ajax_UnitTestCase,WP_Canonical_UnitTestCase,WP_Test_REST_TestCase,WP_Test_REST_Controller_Testcase,WP_Test_REST_Post_Type_Controller_Testcase,WP_XMLRPC_UnitTestCase"/>
+		</properties>
+	</rule>
+
+	<!-- Exclude the unit tests from select sniffs. -->
+	<rule ref="WordPress.Files.FileName.NotHyphenatedLowercase">
+		<exclude-pattern>/tests/phpunit/tests/*</exclude-pattern>
+	</rule>
+	<rule ref="PEAR.NamingConventions.ValidClassName.Invalid">
+		<exclude-pattern>/tests/phpunit/tests/*</exclude-pattern>
+	</rule>
+
+</ruleset>