diff --git a/packages/create-subscription/package.json b/packages/create-subscription/package.json
index b28cd18dd83..31f4c2b7d80 100644
--- a/packages/create-subscription/package.json
+++ b/packages/create-subscription/package.json
@@ -6,6 +6,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs/"
   ],
diff --git a/packages/eslint-plugin-react-hooks/package.json b/packages/eslint-plugin-react-hooks/package.json
index 598758798fa..efac100e7ed 100644
--- a/packages/eslint-plugin-react-hooks/package.json
+++ b/packages/eslint-plugin-react-hooks/package.json
@@ -7,6 +7,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs"
   ],
diff --git a/packages/jest-react/package.json b/packages/jest-react/package.json
index dc5cf76d0d7..d0604366855 100644
--- a/packages/jest-react/package.json
+++ b/packages/jest-react/package.json
@@ -22,6 +22,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs/"
   ]
diff --git a/packages/react-art/package.json b/packages/react-art/package.json
index 02a60854633..32db7ca7637 100644
--- a/packages/react-art/package.json
+++ b/packages/react-art/package.json
@@ -31,6 +31,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs/",
     "umd/",
diff --git a/packages/react-cache/package.json b/packages/react-cache/package.json
index b608fb31286..d31f140c42c 100644
--- a/packages/react-cache/package.json
+++ b/packages/react-cache/package.json
@@ -7,6 +7,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs/",
     "umd/"
diff --git a/packages/react-debug-tools/package.json b/packages/react-debug-tools/package.json
index ea013d1aba2..405705dde59 100644
--- a/packages/react-debug-tools/package.json
+++ b/packages/react-debug-tools/package.json
@@ -12,6 +12,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs/"
   ],
diff --git a/packages/react-dom/package.json b/packages/react-dom/package.json
index 0900718323f..d92c95f7d3b 100644
--- a/packages/react-dom/package.json
+++ b/packages/react-dom/package.json
@@ -24,6 +24,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "profiling.js",
     "server.js",
diff --git a/packages/react-is/package.json b/packages/react-is/package.json
index 5ff1d680295..70db5a95add 100644
--- a/packages/react-is/package.json
+++ b/packages/react-is/package.json
@@ -15,6 +15,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs/",
     "umd/"
diff --git a/packages/react-noop-renderer/package.json b/packages/react-noop-renderer/package.json
index 22f5d5d8f9e..51b668a366b 100644
--- a/packages/react-noop-renderer/package.json
+++ b/packages/react-noop-renderer/package.json
@@ -18,6 +18,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "persistent.js",
     "cjs/"
diff --git a/packages/react-reconciler/package.json b/packages/react-reconciler/package.json
index 1d4bbe9416b..906a58ed400 100644
--- a/packages/react-reconciler/package.json
+++ b/packages/react-reconciler/package.json
@@ -11,6 +11,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "persistent.js",
     "reflection.js",
diff --git a/packages/react-test-renderer/package.json b/packages/react-test-renderer/package.json
index 2525b17a430..6012653435e 100644
--- a/packages/react-test-renderer/package.json
+++ b/packages/react-test-renderer/package.json
@@ -26,6 +26,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "shallow.js",
     "cjs/",
diff --git a/packages/react/package.json b/packages/react/package.json
index 7c599040629..623b1d18081 100644
--- a/packages/react/package.json
+++ b/packages/react/package.json
@@ -11,6 +11,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "cjs/",
     "umd/"
diff --git a/packages/scheduler/package.json b/packages/scheduler/package.json
index 380a3c8e92a..cbba2e88796 100644
--- a/packages/scheduler/package.json
+++ b/packages/scheduler/package.json
@@ -19,6 +19,7 @@
   "files": [
     "LICENSE",
     "README.md",
+    "build-info.json",
     "index.js",
     "tracing.js",
     "tracing-profiling.js",
diff --git a/scripts/circleci/add_build_info_json.sh b/scripts/circleci/add_build_info_json.sh
new file mode 100755
index 00000000000..122d859535b
--- /dev/null
+++ b/scripts/circleci/add_build_info_json.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+
+set -e
+
+node ./scripts/release/ci-add-build-info-json.js
diff --git a/scripts/circleci/test_entry_point.sh b/scripts/circleci/test_entry_point.sh
index c452eebc00c..5b46ec45d3b 100755
--- a/scripts/circleci/test_entry_point.sh
+++ b/scripts/circleci/test_entry_point.sh
@@ -25,6 +25,8 @@ if [ $((1 % CIRCLE_NODE_TOTAL)) -eq "$CIRCLE_NODE_INDEX" ]; then
 fi
 
 if [ $((2 % CIRCLE_NODE_TOTAL)) -eq "$CIRCLE_NODE_INDEX" ]; then
+  COMMANDS_TO_RUN+=('./scripts/circleci/add_build_info_json.sh')
+  COMMANDS_TO_RUN+=('./scripts/circleci/update_package_versions.sh')
   COMMANDS_TO_RUN+=('./scripts/circleci/build.sh')
   COMMANDS_TO_RUN+=('yarn test-build --maxWorkers=2')
   COMMANDS_TO_RUN+=('yarn test-build-prod --maxWorkers=2')
diff --git a/scripts/circleci/update_package_versions.sh b/scripts/circleci/update_package_versions.sh
new file mode 100755
index 00000000000..3661e80cdef
--- /dev/null
+++ b/scripts/circleci/update_package_versions.sh
@@ -0,0 +1,5 @@
+#!/bin/bash
+
+set -e
+
+node ./scripts/release/ci-update-package-versions.js
diff --git a/scripts/release/build-commands/build-artifacts.js b/scripts/release/build-commands/build-artifacts.js
deleted file mode 100644
index 8687c90d401..00000000000
--- a/scripts/release/build-commands/build-artifacts.js
+++ /dev/null
@@ -1,32 +0,0 @@
-#!/usr/bin/env node
-
-'use strict';
-
-const {exec} = require('child-process-promise');
-const {execRead, execUnlessDry, logPromise} = require('../utils');
-
-const run = async ({cwd, dry, version}) => {
-  await exec('yarn build -- --extract-errors', {cwd});
-
-  const modifiedFiles = await execRead('git ls-files -m', {cwd});
-
-  if (modifiedFiles.includes('scripts/error-codes/codes.json')) {
-    await execUnlessDry('git add scripts/error-codes/codes.json', {cwd, dry});
-    await execUnlessDry(
-      `git commit -m "Update error codes for ${version} release"`,
-      {cwd, dry}
-    );
-  }
-
-  if (modifiedFiles.includes('scripts/rollup/results.json')) {
-    await execUnlessDry('git add scripts/rollup/results.json', {cwd, dry});
-    await execUnlessDry(
-      `git commit -m "Update bundle sizes for ${version} release"`,
-      {cwd, dry}
-    );
-  }
-};
-
-module.exports = async params => {
-  return logPromise(run(params), 'Building artifacts', true);
-};
diff --git a/scripts/release/build-commands/print-post-build-summary.js b/scripts/release/build-commands/print-post-build-summary.js
index a9c660d0c58..688159c19b6 100644
--- a/scripts/release/build-commands/print-post-build-summary.js
+++ b/scripts/release/build-commands/print-post-build-summary.js
@@ -43,9 +43,9 @@ module.exports = ({cwd, dry, path, version}) => {
     1. Open {yellow.bold ${standaloneFixturePath}} in the browser.
     2. It should say {italic "Hello world!"}
     3. Next go to {yellow.bold ${packagingFixturesPath}} and run {bold node build-all.js}
-    4. Install the "serve" module ({bold npm install -g serve})
-    5. Go to the repo root and {bold serve -s .}
-    6. Open {blue.bold http://localhost:5000/fixtures/packaging}
+    4. Install the "pushstate-server" module ({bold npm install -g pushstate-server})
+    5. Go to the repo root and {bold pushstate-server -s .}
+    6. Open {blue.bold http://localhost:9000/fixtures/packaging}
     7. Verify every iframe shows {italic "Hello world!"}
 
     After completing the above steps, resume the release process by running:
diff --git a/scripts/release/build.js b/scripts/release/build.js
index 9288af14bf2..721770778a2 100755
--- a/scripts/release/build.js
+++ b/scripts/release/build.js
@@ -6,14 +6,12 @@ const {exec} = require('child_process');
 
 // Follows the steps outlined in github.com/facebook/react/issues/10620
 const run = async () => {
-  const chalk = require('chalk');
-  const logUpdate = require('log-update');
-  const {getPublicPackages, getPackages} = require('./utils');
+  const {getPublicPackages, getPackages, handleError} = require('./utils');
 
   const addGitTag = require('./build-commands/add-git-tag');
-  const buildArtifacts = require('./build-commands/build-artifacts');
+  const buildArtifacts = require('./create-release-commands/build-artifacts');
   const checkCircleCiStatus = require('./build-commands/check-circle-ci-status');
-  const checkEnvironmentVariables = require('./build-commands/check-environment-variables');
+  const checkEnvironmentVariables = require('./shared-commands/check-environment-variables');
   const checkNpmPermissions = require('./build-commands/check-npm-permissions');
   const checkPackageDependencies = require('./build-commands/check-package-dependencies');
   const checkUncommittedChanges = require('./build-commands/check-uncommitted-changes');
@@ -55,18 +53,7 @@ const run = async () => {
     await addGitTag(params);
     await printPostBuildSummary(params);
   } catch (error) {
-    logUpdate.clear();
-
-    const message = error.message.trim().replace(/\n +/g, '\n');
-    const stack = error.stack.replace(error.message, '');
-
-    console.log(
-      `${chalk.bgRed.white(' ERROR ')} ${chalk.red(message)}\n\n${chalk.gray(
-        stack
-      )}`
-    );
-
-    process.exit(1);
+    handleError(error);
   }
 };
 
diff --git a/scripts/release/ci-add-build-info-json.js b/scripts/release/ci-add-build-info-json.js
new file mode 100755
index 00000000000..53444d2ecba
--- /dev/null
+++ b/scripts/release/ci-add-build-info-json.js
@@ -0,0 +1,48 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const {exec} = require('child_process');
+const {existsSync} = require('fs');
+const {join} = require('path');
+
+const run = async () => {
+  const {writeJson} = require('fs-extra');
+  const {getBuildInfo, getPackages} = require('./utils');
+
+  const cwd = join(__dirname, '..', '..');
+
+  const {checksum, commit, branch} = await getBuildInfo();
+
+  const packages = getPackages(join(cwd, 'packages'));
+  const packagesDir = join(cwd, 'packages');
+
+  const buildInfoJSON = {
+    branch,
+    checksum,
+    commit,
+    environment: 'ci',
+  };
+
+  for (let i = 0; i < packages.length; i++) {
+    const packageName = packages[i];
+    const packagePath = join(packagesDir, packageName);
+
+    // Add build info JSON to package
+    if (existsSync(join(packagePath, 'npm'))) {
+      const buildInfoJSONPath = join(packagePath, 'npm', 'build-info.json');
+      await writeJson(buildInfoJSONPath, buildInfoJSON, {spaces: 2});
+    }
+  }
+};
+
+// Install (or update) release script dependencies before proceeding.
+// This needs to be done before we require() the first NPM module.
+exec('yarn install', {cwd: __dirname}, (error, stdout, stderr) => {
+  if (error) {
+    console.error(error);
+    process.exit(1);
+  } else {
+    run();
+  }
+});
diff --git a/scripts/release/ci-update-package-versions.js b/scripts/release/ci-update-package-versions.js
new file mode 100755
index 00000000000..b4441f3f39c
--- /dev/null
+++ b/scripts/release/ci-update-package-versions.js
@@ -0,0 +1,27 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const {exec} = require('child_process');
+const {join} = require('path');
+
+const run = async () => {
+  const {getBuildInfo, updateVersionsForCanary} = require('./utils');
+
+  const cwd = join(__dirname, '..', '..');
+
+  const {version} = await getBuildInfo();
+
+  await updateVersionsForCanary(cwd, version);
+};
+
+// Install (or update) release script dependencies before proceeding.
+// This needs to be done before we require() the first NPM module.
+exec('yarn install', {cwd: __dirname}, (error, stdout, stderr) => {
+  if (error) {
+    console.error(error);
+    process.exit(1);
+  } else {
+    run();
+  }
+});
diff --git a/scripts/release/create-build-commands/add-build-info-json.js b/scripts/release/create-build-commands/add-build-info-json.js
new file mode 100644
index 00000000000..816b2a146eb
--- /dev/null
+++ b/scripts/release/create-build-commands/add-build-info-json.js
@@ -0,0 +1,35 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const {existsSync} = require('fs');
+const {writeJson} = require('fs-extra');
+const {join} = require('path');
+const {getPackages, logPromise} = require('../utils');
+
+const run = async ({branch, checksum, commit, tempDirectory}) => {
+  const packages = getPackages(join(tempDirectory, 'packages'));
+  const packagesDir = join(tempDirectory, 'packages');
+
+  const buildInfoJSON = {
+    branch,
+    checksum,
+    commit,
+    environment: 'local',
+  };
+
+  for (let i = 0; i < packages.length; i++) {
+    const packageName = packages[i];
+    const packagePath = join(packagesDir, packageName);
+
+    // Add build info JSON to package
+    if (existsSync(join(packagePath, 'npm'))) {
+      const buildInfoJSONPath = join(packagePath, 'npm', 'build-info.json');
+      await writeJson(buildInfoJSONPath, buildInfoJSON, {spaces: 2});
+    }
+  }
+};
+
+module.exports = async params => {
+  return logPromise(run(params), 'Adding build metadata to packages');
+};
diff --git a/scripts/release/create-build-commands/build-artifacts.js b/scripts/release/create-build-commands/build-artifacts.js
new file mode 100644
index 00000000000..3435a625b58
--- /dev/null
+++ b/scripts/release/create-build-commands/build-artifacts.js
@@ -0,0 +1,25 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const {exec} = require('child-process-promise');
+const {join} = require('path');
+const {logPromise} = require('../utils');
+
+const run = async ({cwd, dry, tempDirectory}) => {
+  const defaultOptions = {
+    cwd: tempDirectory,
+  };
+
+  await exec('yarn install', defaultOptions);
+  await exec('yarn build -- --extract-errors', defaultOptions);
+
+  const tempNodeModulesPath = join(tempDirectory, 'build', 'node_modules');
+  const buildPath = join(cwd, 'build');
+
+  await exec(`cp -r ${tempNodeModulesPath} ${buildPath}`);
+};
+
+module.exports = async params => {
+  return logPromise(run(params), 'Building artifacts', true);
+};
diff --git a/scripts/release/create-build-commands/copy-repo-to-temp-directory.js b/scripts/release/create-build-commands/copy-repo-to-temp-directory.js
new file mode 100644
index 00000000000..0490efbe67d
--- /dev/null
+++ b/scripts/release/create-build-commands/copy-repo-to-temp-directory.js
@@ -0,0 +1,34 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const chalk = require('chalk');
+const {exec} = require('child-process-promise');
+const {join} = require('path');
+const {tmpdir} = require('os');
+const {logPromise} = require('../utils');
+
+const run = async ({commit, cwd, tempDirectory}) => {
+  const directory = `react-${commit}`;
+  const temp = tmpdir();
+
+  if (tempDirectory !== join(tmpdir(), directory)) {
+    throw Error(`Unexpected temporary directory "${tempDirectory}"`);
+  }
+
+  await exec(`rm -rf ${directory}`, {cwd: temp});
+  await exec(`git archive --format=tar --output=${temp}/react.tgz ${commit}`, {
+    cwd,
+  });
+  await exec(`mkdir ${directory}`, {cwd: temp});
+  await exec(`tar -xf ./react.tgz -C ./${directory}`, {cwd: temp});
+};
+
+module.exports = async params => {
+  return logPromise(
+    run(params),
+    `Copying React repo to temporary directory (${chalk.gray(
+      params.tempDirectory
+    )})`
+  );
+};
diff --git a/scripts/release/create-build-commands/npm-pack-and-unpack.js b/scripts/release/create-build-commands/npm-pack-and-unpack.js
new file mode 100644
index 00000000000..76f3cf85cf8
--- /dev/null
+++ b/scripts/release/create-build-commands/npm-pack-and-unpack.js
@@ -0,0 +1,54 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const {join} = require('path');
+const {exec} = require('child-process-promise');
+const {readdirSync} = require('fs');
+const {readJsonSync} = require('fs-extra');
+const {logPromise} = require('../utils');
+
+const run = async ({cwd, dry, tempDirectory}) => {
+  // Cleanup from previous build.
+  await exec(`rm -rf ${cwd}/build`);
+
+  // NPM pack all built packages.
+  // We do this to ensure that the package.json files array is correct.
+  const builtPackages = readdirSync(join(tempDirectory, 'build/node_modules/'));
+  for (let i = 0; i < builtPackages.length; i++) {
+    await exec(`npm pack ./${builtPackages[i]}`, {
+      cwd: `${tempDirectory}/build/node_modules/`,
+    });
+  }
+
+  await exec('mkdir build');
+  await exec('mkdir build/node_modules');
+  await exec(
+    `cp -r ${tempDirectory}/build/node_modules/*.tgz ${cwd}/build/node_modules/`
+  );
+
+  // Unpack packages and parepare to publish.
+  const compressedPackages = readdirSync('build/node_modules/');
+  for (let i = 0; i < compressedPackages.length; i++) {
+    await exec(
+      `tar -zxvf ${cwd}/build/node_modules/${
+        compressedPackages[i]
+      } -C ${cwd}/build/node_modules/`
+    );
+    const packageJSON = readJsonSync(
+      `${cwd}/build/node_modules/package/package.json`
+    );
+    await exec(
+      `mv ${cwd}/build/node_modules/package ${cwd}/build/node_modules/${
+        packageJSON.name
+      }`
+    );
+  }
+
+  // Cleanup.
+  await exec(`rm ${cwd}/build/node_modules/*.tgz`);
+};
+
+module.exports = async params => {
+  return logPromise(run(params), 'Packing artifacts');
+};
diff --git a/scripts/release/create-build-commands/update-version-numbers.js b/scripts/release/create-build-commands/update-version-numbers.js
new file mode 100644
index 00000000000..f0adc9ae772
--- /dev/null
+++ b/scripts/release/create-build-commands/update-version-numbers.js
@@ -0,0 +1,13 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const chalk = require('chalk');
+const {logPromise, updateVersionsForCanary} = require('../utils');
+
+module.exports = async ({tempDirectory, version}) => {
+  return logPromise(
+    updateVersionsForCanary(tempDirectory, version),
+    `Updating version numbers (${chalk.yellow.bold(version)})`
+  );
+};
diff --git a/scripts/release/create-canary.js b/scripts/release/create-canary.js
new file mode 100755
index 00000000000..0c9652d84fa
--- /dev/null
+++ b/scripts/release/create-canary.js
@@ -0,0 +1,40 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const {tmpdir} = require('os');
+const {join} = require('path');
+const {getBuildInfo, handleError} = require('./utils');
+
+// This local build script exists for special case, manual builds.
+// The typical suggesgted release process is to create a canary from a CI artifact.
+// This build script is optimized for speed and simplicity.
+// It doesn't run all of the tests that the CI environment runs.
+// You're expected to run those manually before publishing a release.
+
+const addBuildInfoJSON = require('./create-build-commands/add-build-info-json');
+const buildArtifacts = require('./create-build-commands/build-artifacts');
+const copyRepoToTempDirectory = require('./create-build-commands/copy-repo-to-temp-directory');
+const npmPackAndUnpack = require('./create-build-commands/npm-pack-and-unpack');
+const printCanarySummary = require('./shared-commands/print-canary-summary');
+const updateVersionNumbers = require('./create-build-commands/update-version-numbers');
+
+const run = async () => {
+  try {
+    const cwd = join(__dirname, '..', '..');
+    const {branch, checksum, commit, version} = await getBuildInfo();
+    const tempDirectory = join(tmpdir(), `react-${commit}`);
+    const params = {branch, checksum, commit, cwd, tempDirectory, version};
+
+    await copyRepoToTempDirectory(params);
+    await updateVersionNumbers(params);
+    await addBuildInfoJSON(params);
+    await buildArtifacts(params);
+    await npmPackAndUnpack(params);
+    await printCanarySummary(params);
+  } catch (error) {
+    handleError(error);
+  }
+};
+
+run();
diff --git a/scripts/release/package.json b/scripts/release/package.json
index c5f9f99af32..21e2d3b2ddc 100644
--- a/scripts/release/package.json
+++ b/scripts/release/package.json
@@ -11,6 +11,7 @@
     "command-line-args": "^4.0.7",
     "command-line-usage": "^4.0.1",
     "figlet": "^1.2.0",
+    "folder-hash": "^2.1.2",
     "fs-extra": "^4.0.2",
     "log-update": "^2.1.0",
     "prompt-promise": "^1.0.3",
diff --git a/scripts/release/prepare-canary-commands/download-build-artifacts.js b/scripts/release/prepare-canary-commands/download-build-artifacts.js
new file mode 100644
index 00000000000..e047b597325
--- /dev/null
+++ b/scripts/release/prepare-canary-commands/download-build-artifacts.js
@@ -0,0 +1,60 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const chalk = require('chalk');
+const http = require('request-promise-json');
+const {exec} = require('child-process-promise');
+const {readdirSync} = require('fs');
+const {readJsonSync} = require('fs-extra');
+const {logPromise} = require('../utils');
+
+const run = async ({build, cwd}) => {
+  // https://circleci.com/docs/2.0/artifacts/#downloading-all-artifacts-for-a-build-on-circleci
+  const metadataURL = `https://circleci.com/api/v1.1/project/github/facebook/react/${build}/artifacts?circle-token=${
+    process.env.CIRCLE_CI_API_TOKEN
+  }`;
+  const metadata = await http.get(metadataURL, true);
+  const nodeModulesURL = metadata.find(
+    entry => entry.path === 'home/circleci/project/node_modules.tgz'
+  ).url;
+
+  // Download and extract artifact
+  await exec(`rm -rf ${cwd}/build/node_modules*`);
+  await exec(`curl ${nodeModulesURL} --output ${cwd}/build/node_modules.tgz`);
+  await exec(`mkdir ${cwd}/build/node_modules`);
+  await exec(
+    `tar zxvf ${cwd}/build/node_modules.tgz -C ${cwd}/build/node_modules/`
+  );
+
+  // Unpack packages and parepare to publish
+  const compressedPackages = readdirSync('build/node_modules/');
+  for (let i = 0; i < compressedPackages.length; i++) {
+    await exec(
+      `tar zxvf ${cwd}/build/node_modules/${
+        compressedPackages[i]
+      } -C ${cwd}/build/node_modules/`
+    );
+    const packageJSON = readJsonSync(
+      `${cwd}/build/node_modules/package/package.json`
+    );
+    await exec(
+      `mv ${cwd}/build/node_modules/package ${cwd}/build/node_modules/${
+        packageJSON.name
+      }`
+    );
+  }
+
+  // Cleanup
+  await exec(`rm ${cwd}/build/node_modules.tgz`);
+  await exec(`rm ${cwd}/build/node_modules/*.tgz`);
+};
+
+module.exports = async ({build, cwd}) => {
+  return logPromise(
+    run({build, cwd}),
+    `Downloading artifacts from Circle CI for build ${chalk.yellow.bold(
+      `${build}`
+    )}`
+  );
+};
diff --git a/scripts/release/prepare-canary-commands/parse-params.js b/scripts/release/prepare-canary-commands/parse-params.js
new file mode 100644
index 00000000000..1e27fe95dd3
--- /dev/null
+++ b/scripts/release/prepare-canary-commands/parse-params.js
@@ -0,0 +1,65 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const chalk = require('chalk');
+const commandLineArgs = require('command-line-args');
+const commandLineUsage = require('command-line-usage');
+const figlet = require('figlet');
+
+const paramDefinitions = [
+  {
+    name: 'build',
+    type: Number,
+    description:
+      'Circle CI build identifier (e.g. https://circleci.com/gh/facebook/react/<build>)',
+    defaultValue: false,
+  },
+  {
+    name: 'path',
+    type: String,
+    alias: 'p',
+    description:
+      'Location of React repository to release; defaults to [bold]{cwd}',
+    defaultValue: '.',
+  },
+];
+
+module.exports = () => {
+  const params = commandLineArgs(paramDefinitions);
+
+  if (!params.build) {
+    const usage = commandLineUsage([
+      {
+        content: chalk
+          .hex('#61dafb')
+          .bold(figlet.textSync('react', {font: 'Graffiti'})),
+        raw: true,
+      },
+      {
+        content:
+          'Prepare a Circle CI build to be published to NPM as a canary.',
+      },
+      {
+        header: 'Options',
+        optionList: paramDefinitions,
+      },
+      {
+        header: 'Examples',
+        content: [
+          {
+            desc: 'Example:',
+            example: '$ ./prepare-canary.js [bold]{--build=}[underline]{12639}',
+          },
+        ],
+      },
+    ]);
+    console.log(usage);
+    process.exit(1);
+  }
+
+  return {
+    ...params,
+    cwd: params.path, // For script convenience
+  };
+};
diff --git a/scripts/release/prepare-canary.js b/scripts/release/prepare-canary.js
new file mode 100755
index 00000000000..2a459722d36
--- /dev/null
+++ b/scripts/release/prepare-canary.js
@@ -0,0 +1,24 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const {handleError} = require('./utils');
+
+const checkEnvironmentVariables = require('./shared-commands/check-environment-variables');
+const downloadBuildArtifacts = require('./prepare-canary-commands/download-build-artifacts');
+const parseParams = require('./prepare-canary-commands/parse-params');
+const printCanarySummary = require('./shared-commands/print-canary-summary');
+
+const run = async () => {
+  try {
+    const params = parseParams();
+
+    await checkEnvironmentVariables(params);
+    await downloadBuildArtifacts(params);
+    await printCanarySummary(params);
+  } catch (error) {
+    handleError(error);
+  }
+};
+
+run();
diff --git a/scripts/release/publish.js b/scripts/release/publish.js
index c3d980b0f24..4f242041488 100755
--- a/scripts/release/publish.js
+++ b/scripts/release/publish.js
@@ -2,9 +2,7 @@
 
 'use strict';
 
-const chalk = require('chalk');
-const logUpdate = require('log-update');
-const {getPublicPackages} = require('./utils');
+const {getPublicPackages, handleError} = require('./utils');
 
 const checkBuildStatus = require('./publish-commands/check-build-status');
 const commitChangelog = require('./publish-commands/commit-changelog');
@@ -27,18 +25,7 @@ const run = async () => {
     await publishToNpm(params);
     await printPostPublishSummary(params);
   } catch (error) {
-    logUpdate.clear();
-
-    const message = error.message.trim().replace(/\n +/g, '\n');
-    const stack = error.stack.replace(error.message, '');
-
-    console.log(
-      `${chalk.bgRed.white(' ERROR ')} ${chalk.red(message)}\n\n${chalk.gray(
-        stack
-      )}`
-    );
-
-    process.exit(1);
+    handleError(error);
   }
 };
 
diff --git a/scripts/release/build-commands/check-environment-variables.js b/scripts/release/shared-commands/check-environment-variables.js
similarity index 100%
rename from scripts/release/build-commands/check-environment-variables.js
rename to scripts/release/shared-commands/check-environment-variables.js
diff --git a/scripts/release/shared-commands/print-canary-summary.js b/scripts/release/shared-commands/print-canary-summary.js
new file mode 100644
index 00000000000..950f2e1a300
--- /dev/null
+++ b/scripts/release/shared-commands/print-canary-summary.js
@@ -0,0 +1,40 @@
+#!/usr/bin/env node
+
+'use strict';
+
+const chalk = require('chalk');
+const {join, relative} = require('path');
+
+module.exports = ({cwd, build, path}) => {
+  const publishPath = relative(
+    process.env.PWD,
+    join(__dirname, '../publish.js')
+  );
+  const command = `${publishPath}` + (path ? ` -p ${path}` : '');
+
+  const packagingFixturesPath = join(cwd, 'fixtures/packaging');
+  const standaloneFixturePath = join(
+    cwd,
+    'fixtures/packaging/babel-standalone/dev.html'
+  );
+
+  console.log(
+    chalk`
+    {green.bold A potential canary has been prepared!}
+    Next there are a couple of manual steps:
+
+    {bold.underline Smoke test the packages}
+
+    1. Open {yellow.bold ${standaloneFixturePath}} in the browser.
+    2. It should say {italic "Hello world!"}
+    3. Next go to {yellow.bold ${packagingFixturesPath}} and run {bold node build-all.js}
+    4. Install the "pushstate-server" module ({bold npm install -g pushstate-server})
+    5. Go to the repo root and {bold pushstate-server -s .}
+    6. Open {blue.bold http://localhost:9000/fixtures/packaging}
+    7. Verify every iframe shows {italic "Hello world!"}
+
+    After completing the above steps, you can publish this canary by running:
+    {yellow.bold ${command}}
+  `.replace(/\n +/g, '\n')
+  );
+};
diff --git a/scripts/release/utils.js b/scripts/release/utils.js
index 2a9ecff5e89..c909c8679b8 100644
--- a/scripts/release/utils.js
+++ b/scripts/release/utils.js
@@ -2,8 +2,10 @@
 
 const chalk = require('chalk');
 const {dots} = require('cli-spinners');
-const {exec} = require('child-process-promise');
-const {readdirSync, readFileSync, statSync} = require('fs');
+const {exec, spawn} = require('child-process-promise');
+const {hashElement} = require('folder-hash');
+const {readdirSync, readFileSync, statSync, writeFileSync} = require('fs');
+const {readJson, writeJson} = require('fs-extra');
 const logUpdate = require('log-update');
 const {join} = require('path');
 
@@ -23,9 +25,31 @@ const execUnlessDry = async (command, {cwd, dry}) => {
   }
 };
 
-const getPackages = () => {
-  const packagesRoot = join(__dirname, '..', '..', 'packages');
+const getBuildInfo = async () => {
+  const cwd = join(__dirname, '..', '..');
+
+  const branch = await execRead('git branch | grep \\* | cut -d " " -f2', {
+    cwd,
+  });
+  const commit = await execRead('git show -s --format=%h', {cwd});
+  const checksum = await getChecksumForCurrentRevision(cwd);
+  const version = `0.0.0-${commit}`;
 
+  return {branch, checksum, commit, version};
+};
+
+const getChecksumForCurrentRevision = async cwd => {
+  const packagesDir = join(cwd, 'packages');
+  const hashedPackages = await hashElement(packagesDir, {
+    encoding: 'hex',
+    files: {exclude: ['.DS_Store']},
+  });
+  return hashedPackages.hash.slice(0, 7);
+};
+
+const getPackages = (
+  packagesRoot = join(__dirname, '..', '..', 'packages')
+) => {
   return readdirSync(packagesRoot).filter(dir => {
     const packagePath = join(packagesRoot, dir, 'package.json');
 
@@ -67,6 +91,21 @@ const getUnexecutedCommands = () => {
   }
 };
 
+const handleError = error => {
+  logUpdate.clear();
+
+  const message = error.message.trim().replace(/\n +/g, '\n');
+  const stack = error.stack.replace(error.message, '');
+
+  console.log(
+    `${chalk.bgRed.white(' ERROR ')} ${chalk.red(message)}\n\n${chalk.gray(
+      stack
+    )}`
+  );
+
+  process.exit(1);
+};
+
 const logPromise = async (promise, text, isLongRunningTask = false) => {
   const {frames, interval} = dots;
 
@@ -113,12 +152,77 @@ const runYarnTask = async (cwd, task, errorMessage) => {
   }
 };
 
+const spawnCommand = (command, options) =>
+  spawn(command, {
+    cwd: join(__dirname, '..', '..'),
+    encoding: 'utf-8',
+    env: process.env,
+    shell: true,
+    stdio: [process.stdin, process.stdout, process.stderr],
+    ...options,
+  });
+
+const updateVersionsForCanary = async (cwd, version) => {
+  const packages = getPackages(join(cwd, 'packages'));
+  const packagesDir = join(cwd, 'packages');
+
+  // Update the shared React version source file.
+  // This is bundled into built renderers.
+  // The promote script will replace this with a final version later.
+  const reactVersionPath = join(cwd, 'packages/shared/ReactVersion.js');
+  const reactVersion = readFileSync(reactVersionPath, 'utf8').replace(
+    /module\.exports = '[^']+';/,
+    `module.exports = '${version}';`
+  );
+  writeFileSync(reactVersionPath, reactVersion);
+
+  // Update the root package.json.
+  // This is required to pass a later version check script.
+  {
+    const packageJSONPath = join(cwd, 'package.json');
+    const packageJSON = await readJson(packageJSONPath);
+    packageJSON.version = version;
+    await writeJson(packageJSONPath, packageJSON, {spaces: 2});
+  }
+
+  for (let i = 0; i < packages.length; i++) {
+    const packageName = packages[i];
+    const packagePath = join(packagesDir, packageName);
+
+    // Update version numbers in package JSONs
+    const packageJSONPath = join(packagePath, 'package.json');
+    const packageJSON = await readJson(packageJSONPath);
+    packageJSON.version = version;
+
+    // Also update inter-package dependencies.
+    // Canary releases always have exact version matches.
+    // The promote script may later relax these (e.g. "^x.x.x") based on source package JSONs.
+    const {dependencies, peerDependencies} = packageJSON;
+    for (let j = 0; j < packages.length; j++) {
+      const dependencyName = packages[j];
+      if (dependencies && dependencies[dependencyName]) {
+        dependencies[dependencyName] = version;
+      }
+      if (peerDependencies && peerDependencies[dependencyName]) {
+        peerDependencies[dependencyName] = version;
+      }
+    }
+
+    await writeJson(packageJSONPath, packageJSON, {spaces: 2});
+  }
+};
+
 module.exports = {
   execRead,
   execUnlessDry,
+  getBuildInfo,
+  getChecksumForCurrentRevision,
   getPackages,
   getPublicPackages,
   getUnexecutedCommands,
+  handleError,
   logPromise,
   runYarnTask,
+  spawnCommand,
+  updateVersionsForCanary,
 };
diff --git a/scripts/release/yarn.lock b/scripts/release/yarn.lock
index 44ea4e5703a..240210db6c7 100644
--- a/scripts/release/yarn.lock
+++ b/scripts/release/yarn.lock
@@ -63,6 +63,11 @@ aws4@^1.6.0:
   version "1.6.0"
   resolved "https://registry.yarnpkg.com/aws4/-/aws4-1.6.0.tgz#83ef5ca860b2b32e4a0deedee8c771b9db57471e"
 
+balanced-match@^1.0.0:
+  version "1.0.0"
+  resolved "https://registry.yarnpkg.com/balanced-match/-/balanced-match-1.0.0.tgz#89b4d199ab2bee49de164ea02b89ce462d71b767"
+  integrity sha1-ibTRmasr7kneFk6gK4nORi1xt2c=
+
 bcrypt-pbkdf@^1.0.0:
   version "1.0.1"
   resolved "https://registry.yarnpkg.com/bcrypt-pbkdf/-/bcrypt-pbkdf-1.0.1.tgz#63bc5dcb61331b92bc05fd528953c33462a06f8d"
@@ -81,6 +86,14 @@ boom@5.x.x:
   dependencies:
     hoek "4.x.x"
 
+brace-expansion@^1.1.7:
+  version "1.1.11"
+  resolved "https://registry.yarnpkg.com/brace-expansion/-/brace-expansion-1.1.11.tgz#3c7fcbf529d87226f3d2f52b966ff5271eb441dd"
+  integrity sha512-iCuPHDFgrHX7H2vEI/5xpz07zSHB00TpugqhmYtVmMO6518mCuRMoOYFldEBl0g187ufozdaHgWKcYFb61qGiA==
+  dependencies:
+    balanced-match "^1.0.0"
+    concat-map "0.0.1"
+
 caseless@~0.12.0:
   version "0.12.0"
   resolved "https://registry.yarnpkg.com/caseless/-/caseless-0.12.0.tgz#1b681c21ff84033c826543090689420d187151dc"
@@ -148,6 +161,11 @@ command-line-usage@^4.0.1:
     table-layout "^0.4.1"
     typical "^2.6.1"
 
+concat-map@0.0.1:
+  version "0.0.1"
+  resolved "https://registry.yarnpkg.com/concat-map/-/concat-map-0.0.1.tgz#d8a96bd77fd68df7793a73036a3ba0d5405d477b"
+  integrity sha1-2Klr13/Wjfd5OnMDajug1UBdR3s=
+
 core-util-is@1.0.2:
   version "1.0.2"
   resolved "https://registry.yarnpkg.com/core-util-is/-/core-util-is-1.0.2.tgz#b5fd54220aa2bc5ab57aab7140c940754503c1a7"
@@ -171,6 +189,13 @@ dashdash@^1.12.0:
   dependencies:
     assert-plus "^1.0.0"
 
+debug@^3.1.0:
+  version "3.2.6"
+  resolved "https://registry.yarnpkg.com/debug/-/debug-3.2.6.tgz#e83d17de16d8a7efb7717edbe5fb10135eee629b"
+  integrity sha512-mel+jf7nrtEl5Pn1Qx46zARXKDpBbvzezse7p7LqINmdoIk8PYP5SySaxEmYv6TZ0JyEKA1hsCId6DIhgITtWQ==
+  dependencies:
+    ms "^2.1.1"
+
 deep-extend@~0.5.0:
   version "0.5.0"
   resolved "https://registry.yarnpkg.com/deep-extend/-/deep-extend-0.5.0.tgz#6ef4a09b05f98b0e358d6d93d4ca3caec6672803"
@@ -212,6 +237,15 @@ find-replace@^1.0.3:
     array-back "^1.0.4"
     test-value "^2.1.0"
 
+folder-hash@^2.1.2:
+  version "2.1.2"
+  resolved "https://registry.yarnpkg.com/folder-hash/-/folder-hash-2.1.2.tgz#7109f9cd0cbca271936d1b5544b156d6571e6cfd"
+  integrity sha512-PmMwEZyNN96EMshf7sek4OIB7ADNsHOJ7VIw7pO0PBI0BNfEsi7U8U56TBjjqqwQ0WuBv8se0HEfmbw5b/Rk+w==
+  dependencies:
+    debug "^3.1.0"
+    graceful-fs "~4.1.11"
+    minimatch "~3.0.4"
+
 forever-agent@~0.6.1:
   version "0.6.1"
   resolved "https://registry.yarnpkg.com/forever-agent/-/forever-agent-0.6.1.tgz#fbc71f0c41adeb37f96c577ad1ed42d8fdacca91"
@@ -242,6 +276,11 @@ graceful-fs@^4.1.2, graceful-fs@^4.1.6:
   version "4.1.11"
   resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.11.tgz#0e8bdfe4d1ddb8854d64e04ea7c00e2a026e5658"
 
+graceful-fs@~4.1.11:
+  version "4.1.15"
+  resolved "https://registry.yarnpkg.com/graceful-fs/-/graceful-fs-4.1.15.tgz#ffb703e1066e8a0eeaa4c8b80ba9253eeefbfb00"
+  integrity sha512-6uHUhOPEBgQ24HM+r6b/QwWfZq+yiFcipKFrOFiBEnWdy5sdzYoi+pJeQaPI5qOLRFqWmAXUPQNsielzdLoecA==
+
 har-schema@^2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/har-schema/-/har-schema-2.0.0.tgz#a94c2224ebcac04782a0d9035521f24735b7ec92"
@@ -372,6 +411,18 @@ mimic-fn@^1.0.0:
   version "1.1.0"
   resolved "https://registry.yarnpkg.com/mimic-fn/-/mimic-fn-1.1.0.tgz#e667783d92e89dbd342818b5230b9d62a672ad18"
 
+minimatch@~3.0.4:
+  version "3.0.4"
+  resolved "https://registry.yarnpkg.com/minimatch/-/minimatch-3.0.4.tgz#5166e286457f03306064be5497e8dbb0c3d32083"
+  integrity sha512-yJHVQEhyqPLUTgt9B83PXu6W3rx4MvvHvSUvToogpwoGDOUQ+yDrR0HRot+yOCdCO7u4hX3pWft6kWBBcqh0UA==
+  dependencies:
+    brace-expansion "^1.1.7"
+
+ms@^2.1.1:
+  version "2.1.1"
+  resolved "https://registry.yarnpkg.com/ms/-/ms-2.1.1.tgz#30a5864eb3ebb0a66f2ebe6d727af06a09d86e0a"
+  integrity sha512-tgp+dl5cGk28utYktBsrFqA7HKgrhgPsg6Z/EfhWI4gl1Hwq8B/GmY/0oXZ6nF8hDVesS/FpnYaD/kOWhYQvyg==
+
 native-or-another@~2.0.0:
   version "2.0.0"
   resolved "https://registry.yarnpkg.com/native-or-another/-/native-or-another-2.0.0.tgz#17a567f92beea9cd71acff96a7681a735eca3bff"