diff --git a/packages/build/src/config/redact-config.spec.ts b/packages/build/src/config/redact-config.spec.ts
new file mode 100644
index 0000000000..75f9a1164e
--- /dev/null
+++ b/packages/build/src/config/redact-config.spec.ts
@@ -0,0 +1,28 @@
+import { expect } from 'chai';
+import { Config } from './config';
+import { redactConfig } from './redact-config';
+
+describe('config redact-config', () => {
+  const redactedKeys: Array<keyof Config> = [
+    'evgAwsKey',
+    'evgAwsSecret',
+    'downloadCenterAwsKey',
+    'downloadCenterAwsSecret',
+    'githubToken'
+  ];
+
+  const config: Config = {} as Config;
+
+  beforeEach(() => {
+    redactedKeys.forEach(k => {
+      (config as any)[k] = 'asecret';
+    });
+  });
+
+  redactedKeys.forEach(k => {
+    it(`removes ${k} from the config`, () => {
+      const redacted = redactConfig(config);
+      expect(redacted[k]).to.be.undefined;
+    });
+  });
+});
diff --git a/packages/build/src/npm-packages.spec.ts b/packages/build/src/npm-packages.spec.ts
deleted file mode 100644
index 4e33789f68..0000000000
--- a/packages/build/src/npm-packages.spec.ts
+++ /dev/null
@@ -1,222 +0,0 @@
-import { expect } from 'chai';
-import path from 'path';
-import sinon, { SinonStub } from 'sinon';
-import {
-  bumpNpmPackages,
-  listNpmPackages,
-  markBumpedFilesAsAssumeUnchanged,
-  publishNpmPackages,
-  spawnSync,
-  LernaPackageDescription
-} from './npm-packages';
-
-
-describe('npm-packages', () => {
-  describe('spawnSync', () => {
-    it('works for a valid command', () => {
-      const result = spawnSync('bash', ['-c', 'echo -n works'], { encoding: 'utf8' });
-      expect(result.status).to.equal(0);
-      expect(result.stdout).to.equal('works');
-    });
-
-    it('throws on ENOENT error', () => {
-      try {
-        spawnSync('notaprogram', [], { encoding: 'utf8' });
-      } catch (e) {
-        return expect(e).to.not.be.undefined;
-      }
-      expect.fail('Expected error');
-    });
-
-    it('throws on non-zero exit code', () => {
-      try {
-        spawnSync('bash', ['-c', 'exit 1'], { encoding: 'utf8' });
-      } catch (e) {
-        return expect(e).to.not.be.undefined;
-      }
-      expect.fail('Expected error');
-    });
-
-    it('ignores errors when asked to for ENOENT', () => {
-      const result = spawnSync('notaprogram', [], { encoding: 'utf8' }, true);
-      expect(result).to.not.be.undefined;
-    });
-
-    it('ignores errors when asked to for non-zero exit code', () => {
-      const result = spawnSync('bash', ['-c', 'exit 1'], { encoding: 'utf8' }, true);
-      expect(result).to.not.be.undefined;
-      expect(result?.status).to.equal(1);
-    });
-  });
-
-  describe('bumpNpmPackages', () => {
-    let spawnSync: SinonStub;
-
-    beforeEach(() => {
-      spawnSync = sinon.stub();
-    });
-
-    it('does not do anything if no version or placeholder version is specified', () => {
-      bumpNpmPackages('', spawnSync);
-      bumpNpmPackages('0.0.0-dev.0', spawnSync);
-      expect(spawnSync).to.not.have.been.called;
-    });
-
-    it('calls lerna to bump package version', () => {
-      const lernaBin = path.resolve(__dirname, '..', '..', '..', 'node_modules', '.bin', 'lerna');
-      bumpNpmPackages('0.7.0', spawnSync);
-      expect(spawnSync).to.have.been.calledWith(
-        lernaBin,
-        ['version', '0.7.0', '--no-changelog', '--no-push', '--exact', '--no-git-tag-version', '--force-publish', '--yes'],
-        sinon.match.any
-      );
-      expect(spawnSync).to.have.been.calledWith(
-        'git',
-        ['status', '--porcelain'],
-        sinon.match.any
-      );
-    });
-  });
-
-  describe('publishNpmPackages', () => {
-    let listNpmPackages: SinonStub;
-    let markBumpedFilesAsAssumeUnchanged: SinonStub;
-    let spawnSync: SinonStub;
-
-    beforeEach(() => {
-      listNpmPackages = sinon.stub();
-      markBumpedFilesAsAssumeUnchanged = sinon.stub();
-      spawnSync = sinon.stub();
-    });
-
-    it('fails if packages have different versions', () => {
-      listNpmPackages.returns([
-        { name: 'packageA', version: '0.0.1' },
-        { name: 'packageB', version: '0.0.2' }
-      ]);
-      try {
-        publishNpmPackages(
-          listNpmPackages,
-          markBumpedFilesAsAssumeUnchanged,
-          spawnSync
-        );
-      } catch (e) {
-        expect(markBumpedFilesAsAssumeUnchanged).to.not.have.been.called;
-        expect(spawnSync).to.not.have.been.called;
-        return;
-      }
-      expect.fail('Expected error');
-    });
-
-    it('fails if packages have placeholder versions', () => {
-      listNpmPackages.returns([
-        { name: 'packageA', version: '0.0.0-dev.0' },
-        { name: 'packageB', version: '0.0.0-dev.0' }
-      ]);
-      try {
-        publishNpmPackages(
-          listNpmPackages,
-          markBumpedFilesAsAssumeUnchanged,
-          spawnSync
-        );
-      } catch (e) {
-        expect(markBumpedFilesAsAssumeUnchanged).to.not.have.been.called;
-        expect(spawnSync).to.not.have.been.called;
-        return;
-      }
-      expect.fail('Expected error');
-    });
-
-    it('calls lerna to publish packages for a real version', () => {
-      const lernaBin = path.resolve(__dirname, '..', '..', '..', 'node_modules', '.bin', 'lerna');
-      const packages = [
-        { name: 'packageA', version: '0.7.0' }
-      ];
-      listNpmPackages.returns(packages);
-
-      publishNpmPackages(
-        listNpmPackages,
-        markBumpedFilesAsAssumeUnchanged,
-        spawnSync
-      );
-
-      expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, true);
-      expect(spawnSync).to.have.been.calledWith(
-        lernaBin,
-        ['publish', 'from-package', '--no-changelog', '--no-push', '--exact', '--no-git-tag-version', '--force-publish', '--yes'],
-        sinon.match.any
-      );
-      expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, false);
-    });
-
-    it('reverts the assume unchanged even on spawn failure', () => {
-      const packages = [
-        { name: 'packageA', version: '0.7.0' }
-      ];
-      listNpmPackages.returns(packages);
-      spawnSync.throws(new Error('meeep'));
-
-      try {
-        publishNpmPackages(
-          listNpmPackages,
-          markBumpedFilesAsAssumeUnchanged,
-          spawnSync
-        );
-      } catch (e) {
-        expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, true);
-        expect(spawnSync).to.have.been.called;
-        expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, false);
-        return;
-      }
-      expect.fail('Expected error');
-    });
-  });
-
-  describe('listNpmPackages', () => {
-    it('lists packages', () => {
-      const packages = listNpmPackages();
-      expect(packages.length).to.be.greaterThan(1);
-      for (const { name, version } of packages) {
-        expect(name).to.be.a('string');
-        expect(version).to.be.a('string');
-      }
-    });
-  });
-
-  describe('markBumpedFilesAsAssumeUnchanged', () => {
-    let packages: LernaPackageDescription[];
-    let expectedFiles: string[];
-    let spawnSync: SinonStub;
-
-    beforeEach(() => {
-      expectedFiles = [
-        path.resolve(__dirname, '..', '..', '..', 'lerna.json')
-      ];
-      packages = listNpmPackages();
-      packages.forEach(({ location }) => {
-        expectedFiles.push(path.resolve(location, 'package.json'));
-        expectedFiles.push(path.resolve(location, 'package-lock.json'));
-      });
-
-      spawnSync = sinon.stub();
-    });
-
-    it('marks files with --assume-unchanged', () => {
-      markBumpedFilesAsAssumeUnchanged(packages, true, spawnSync);
-      expectedFiles.forEach(f => {
-        expect(spawnSync).to.have.been.calledWith(
-          'git', ['update-index', '--assume-unchanged', f], sinon.match.any
-        );
-      });
-    });
-
-    it('marks files with --no-assume-unchanged', () => {
-      markBumpedFilesAsAssumeUnchanged(packages, false, spawnSync);
-      expectedFiles.forEach(f => {
-        expect(spawnSync).to.have.been.calledWith(
-          'git', ['update-index', '--no-assume-unchanged', f], sinon.match.any
-        );
-      });
-    });
-  });
-});
diff --git a/packages/build/src/npm-packages.ts b/packages/build/src/npm-packages.ts
deleted file mode 100644
index f8746bc986..0000000000
--- a/packages/build/src/npm-packages.ts
+++ /dev/null
@@ -1,156 +0,0 @@
-import { SpawnSyncOptionsWithStringEncoding, SpawnSyncReturns } from 'child_process';
-import * as spawn from 'cross-spawn';
-import path from 'path';
-
-const PLACEHOLDER_VERSION = '0.0.0-dev.0';
-const PROJECT_ROOT = path.resolve(__dirname, '..', '..', '..');
-const LERNA_BIN = path.resolve(PROJECT_ROOT, 'node_modules', '.bin', 'lerna');
-
-export interface LernaPackageDescription {
-  name: string;
-  version: string;
-  private: boolean;
-  location: string;
-}
-
-export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding): SpawnSyncReturns<string>;
-export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors: false): SpawnSyncReturns<string>;
-export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors: true): SpawnSyncReturns<string> | undefined;
-export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors = false): SpawnSyncReturns<string> | undefined {
-  const result = spawn.sync(command, args, options);
-  if (result.error) {
-    console.error('spawn.sync returned error', result.error);
-    console.error(result.stdout);
-    console.error(result.stderr);
-
-    if (!ignoreErrors) {
-      throw new Error(`Failed to spawn ${command}, args: ${args.join(',')}: ${result.error}`);
-    } else {
-      console.warn('Ignoring error and continuing...');
-    }
-  } else if (result.status !== 0) {
-    console.error('spawn.sync exited with non-zero', result.status);
-    console.error(result.stdout);
-    console.error(result.stderr);
-    if (!ignoreErrors) {
-      throw new Error(`Spawn exited non-zero for ${command}, args: ${args.join(',')}: ${result.status}`);
-    } else {
-      console.warn('Ignoring error and continuing...');
-    }
-  }
-  return result;
-}
-
-export function bumpNpmPackages(
-  version: string,
-  spawnSyncFn: typeof spawnSync = spawnSync
-): void {
-  if (!version || version === PLACEHOLDER_VERSION) {
-    console.info('mongosh: Not bumping package version, keeping at placeholder');
-    return;
-  }
-
-  console.info(`mongosh: Bumping package versions to ${version}`);
-  spawnSyncFn(LERNA_BIN, [
-    'version',
-    version,
-    '--no-changelog',
-    '--no-push',
-    '--exact',
-    '--no-git-tag-version',
-    '--force-publish',
-    '--yes'
-  ], {
-    stdio: 'inherit',
-    cwd: PROJECT_ROOT,
-    encoding: 'utf8'
-  });
-  spawnSyncFn('git', ['status', '--porcelain'], {
-    stdio: 'inherit',
-    cwd: PROJECT_ROOT,
-    encoding: 'utf8'
-  });
-}
-
-export function publishNpmPackages(
-  listNpmPackagesFn: typeof listNpmPackages = listNpmPackages,
-  markBumpedFilesAsAssumeUnchangedFn: typeof markBumpedFilesAsAssumeUnchanged = markBumpedFilesAsAssumeUnchanged,
-  spawnSyncFn: typeof spawnSync = spawnSync
-): void {
-  const packages = listNpmPackagesFn();
-
-  const versions = Array.from(new Set(packages.map(({ version }) => version)));
-
-  if (versions.length !== 1) {
-    throw new Error(`Refusing to publish packages with multiple versions: ${versions}`);
-  }
-
-  if (versions[0] === PLACEHOLDER_VERSION) {
-    throw new Error('Refusing to publish packages with placeholder version');
-  }
-
-  // Lerna requires a clean repository for a publish from-package (--force-publish does not have any effect here)
-  // we use git update-index --assume-unchanged on files we know have been bumped
-  markBumpedFilesAsAssumeUnchangedFn(packages, true);
-  try {
-    spawnSyncFn(LERNA_BIN, [
-      'publish',
-      'from-package',
-      '--no-changelog',
-      '--no-push',
-      '--exact',
-      '--no-git-tag-version',
-      '--force-publish',
-      '--yes'
-    ], {
-      stdio: 'inherit',
-      cwd: PROJECT_ROOT,
-      encoding: 'utf8'
-    });
-  } finally {
-    markBumpedFilesAsAssumeUnchangedFn(packages, false);
-  }
-}
-
-export function listNpmPackages(): LernaPackageDescription[] {
-  const lernaListOutput = spawnSync(
-    LERNA_BIN, [
-      'list',
-      '--json',
-      '--all'
-    ],
-    {
-      cwd: PROJECT_ROOT,
-      encoding: 'utf8'
-    }
-  );
-
-  return JSON.parse(lernaListOutput.stdout);
-}
-
-export function markBumpedFilesAsAssumeUnchanged(
-  packages: LernaPackageDescription[],
-  assumeUnchanged: boolean,
-  spawnSyncFn: typeof spawnSync = spawnSync
-): void {
-  const filesToAssume = [
-    path.resolve(PROJECT_ROOT, 'lerna.json')
-  ];
-  packages.forEach(({ location }) => {
-    filesToAssume.push(path.resolve(location, 'package.json'));
-    filesToAssume.push(path.resolve(location, 'package-lock.json'));
-  });
-
-  filesToAssume.forEach(f => {
-    spawnSyncFn('git', [
-      'update-index',
-      assumeUnchanged ? '--assume-unchanged' : '--no-assume-unchanged',
-      f
-    ], {
-      stdio: 'inherit',
-      cwd: PROJECT_ROOT,
-      encoding: 'utf8'
-    }, true);
-    console.info(`File ${f} is now ${assumeUnchanged ? '' : 'NOT '}assumed to be unchanged`);
-  });
-}
diff --git a/packages/build/src/npm-packages/bump.spec.ts b/packages/build/src/npm-packages/bump.spec.ts
new file mode 100644
index 0000000000..906a4063a1
--- /dev/null
+++ b/packages/build/src/npm-packages/bump.spec.ts
@@ -0,0 +1,33 @@
+import { expect } from 'chai';
+import path from 'path';
+import sinon, { SinonStub } from 'sinon';
+import { bumpNpmPackages } from './bump';
+
+describe('npm-packages bumpNpmPackages', () => {
+  let spawnSync: SinonStub;
+
+  beforeEach(() => {
+    spawnSync = sinon.stub();
+  });
+
+  it('does not do anything if no version or placeholder version is specified', () => {
+    bumpNpmPackages('', spawnSync);
+    bumpNpmPackages('0.0.0-dev.0', spawnSync);
+    expect(spawnSync).to.not.have.been.called;
+  });
+
+  it('calls lerna to bump package version', () => {
+    const lernaBin = path.resolve(__dirname, '..', '..', '..', '..', 'node_modules', '.bin', 'lerna');
+    bumpNpmPackages('0.7.0', spawnSync);
+    expect(spawnSync).to.have.been.calledWith(
+      lernaBin,
+      ['version', '0.7.0', '--no-changelog', '--no-push', '--exact', '--no-git-tag-version', '--force-publish', '--yes'],
+      sinon.match.any
+    );
+    expect(spawnSync).to.have.been.calledWith(
+      'git',
+      ['status', '--porcelain'],
+      sinon.match.any
+    );
+  });
+});
diff --git a/packages/build/src/npm-packages/bump.ts b/packages/build/src/npm-packages/bump.ts
new file mode 100644
index 0000000000..6964425424
--- /dev/null
+++ b/packages/build/src/npm-packages/bump.ts
@@ -0,0 +1,33 @@
+import { LERNA_BIN, PLACEHOLDER_VERSION, PROJECT_ROOT } from './constants';
+import { spawnSync } from './spawn-sync';
+
+export function bumpNpmPackages(
+  version: string,
+  spawnSyncFn: typeof spawnSync = spawnSync
+): void {
+  if (!version || version === PLACEHOLDER_VERSION) {
+    console.info('mongosh: Not bumping package version, keeping at placeholder');
+    return;
+  }
+
+  console.info(`mongosh: Bumping package versions to ${version}`);
+  spawnSyncFn(LERNA_BIN, [
+    'version',
+    version,
+    '--no-changelog',
+    '--no-push',
+    '--exact',
+    '--no-git-tag-version',
+    '--force-publish',
+    '--yes'
+  ], {
+    stdio: 'inherit',
+    cwd: PROJECT_ROOT,
+    encoding: 'utf8'
+  });
+  spawnSyncFn('git', ['status', '--porcelain'], {
+    stdio: 'inherit',
+    cwd: PROJECT_ROOT,
+    encoding: 'utf8'
+  });
+}
diff --git a/packages/build/src/npm-packages/constants.ts b/packages/build/src/npm-packages/constants.ts
new file mode 100644
index 0000000000..bc5f651ea5
--- /dev/null
+++ b/packages/build/src/npm-packages/constants.ts
@@ -0,0 +1,5 @@
+import path from 'path';
+
+export const PLACEHOLDER_VERSION = '0.0.0-dev.0';
+export const PROJECT_ROOT = path.resolve(__dirname, '..', '..', '..', '..');
+export const LERNA_BIN = path.resolve(PROJECT_ROOT, 'node_modules', '.bin', 'lerna');
diff --git a/packages/build/src/npm-packages/index.ts b/packages/build/src/npm-packages/index.ts
new file mode 100644
index 0000000000..5096a4ef4a
--- /dev/null
+++ b/packages/build/src/npm-packages/index.ts
@@ -0,0 +1,3 @@
+
+export { bumpNpmPackages } from './bump';
+export { publishNpmPackages } from './publish';
diff --git a/packages/build/src/npm-packages/list.spec.ts b/packages/build/src/npm-packages/list.spec.ts
new file mode 100644
index 0000000000..414825ac04
--- /dev/null
+++ b/packages/build/src/npm-packages/list.spec.ts
@@ -0,0 +1,56 @@
+import { expect } from 'chai';
+import path from 'path';
+import sinon, { SinonStub } from 'sinon';
+import { LernaPackageDescription, listNpmPackages } from './list';
+import { markBumpedFilesAsAssumeUnchanged } from './publish';
+
+describe('npm-packages list', () => {
+  describe('listNpmPackages', () => {
+    it('lists packages', () => {
+      const packages = listNpmPackages();
+      expect(packages.length).to.be.greaterThan(1);
+      for (const { name, version } of packages) {
+        expect(name).to.be.a('string');
+        expect(version).to.be.a('string');
+      }
+    });
+  });
+
+
+  describe('markBumpedFilesAsAssumeUnchanged', () => {
+    let packages: LernaPackageDescription[];
+    let expectedFiles: string[];
+    let spawnSync: SinonStub;
+
+    beforeEach(() => {
+      expectedFiles = [
+        path.resolve(__dirname, '..', '..', '..', '..', 'lerna.json')
+      ];
+      packages = listNpmPackages();
+      packages.forEach(({ location }) => {
+        expectedFiles.push(path.resolve(location, 'package.json'));
+        expectedFiles.push(path.resolve(location, 'package-lock.json'));
+      });
+
+      spawnSync = sinon.stub();
+    });
+
+    it('marks files with --assume-unchanged', () => {
+      markBumpedFilesAsAssumeUnchanged(packages, true, spawnSync);
+      expectedFiles.forEach(f => {
+        expect(spawnSync).to.have.been.calledWith(
+          'git', ['update-index', '--assume-unchanged', f], sinon.match.any
+        );
+      });
+    });
+
+    it('marks files with --no-assume-unchanged', () => {
+      markBumpedFilesAsAssumeUnchanged(packages, false, spawnSync);
+      expectedFiles.forEach(f => {
+        expect(spawnSync).to.have.been.calledWith(
+          'git', ['update-index', '--no-assume-unchanged', f], sinon.match.any
+        );
+      });
+    });
+  });
+});
diff --git a/packages/build/src/npm-packages/list.ts b/packages/build/src/npm-packages/list.ts
new file mode 100644
index 0000000000..911240e389
--- /dev/null
+++ b/packages/build/src/npm-packages/list.ts
@@ -0,0 +1,25 @@
+import { LERNA_BIN, PROJECT_ROOT } from './constants';
+import { spawnSync } from './spawn-sync';
+
+export interface LernaPackageDescription {
+    name: string;
+    version: string;
+    private: boolean;
+    location: string;
+}
+
+export function listNpmPackages(): LernaPackageDescription[] {
+  const lernaListOutput = spawnSync(
+    LERNA_BIN, [
+      'list',
+      '--json',
+      '--all'
+    ],
+    {
+      cwd: PROJECT_ROOT,
+      encoding: 'utf8'
+    }
+  );
+
+  return JSON.parse(lernaListOutput.stdout);
+}
diff --git a/packages/build/src/npm-packages/publish.spec.ts b/packages/build/src/npm-packages/publish.spec.ts
new file mode 100644
index 0000000000..44334c6523
--- /dev/null
+++ b/packages/build/src/npm-packages/publish.spec.ts
@@ -0,0 +1,98 @@
+import { expect } from 'chai';
+import path from 'path';
+import sinon, { SinonStub } from 'sinon';
+import { publishNpmPackages } from './publish';
+
+describe('npm-packages publishNpmPackages', () => {
+  let listNpmPackages: SinonStub;
+  let markBumpedFilesAsAssumeUnchanged: SinonStub;
+  let spawnSync: SinonStub;
+
+  beforeEach(() => {
+    listNpmPackages = sinon.stub();
+    markBumpedFilesAsAssumeUnchanged = sinon.stub();
+    spawnSync = sinon.stub();
+  });
+
+  it('fails if packages have different versions', () => {
+    listNpmPackages.returns([
+      { name: 'packageA', version: '0.0.1' },
+      { name: 'packageB', version: '0.0.2' }
+    ]);
+    try {
+      publishNpmPackages(
+        listNpmPackages,
+        markBumpedFilesAsAssumeUnchanged,
+        spawnSync
+      );
+    } catch (e) {
+      expect(markBumpedFilesAsAssumeUnchanged).to.not.have.been.called;
+      expect(spawnSync).to.not.have.been.called;
+      return;
+    }
+    expect.fail('Expected error');
+  });
+
+  it('fails if packages have placeholder versions', () => {
+    listNpmPackages.returns([
+      { name: 'packageA', version: '0.0.0-dev.0' },
+      { name: 'packageB', version: '0.0.0-dev.0' }
+    ]);
+    try {
+      publishNpmPackages(
+        listNpmPackages,
+        markBumpedFilesAsAssumeUnchanged,
+        spawnSync
+      );
+    } catch (e) {
+      expect(markBumpedFilesAsAssumeUnchanged).to.not.have.been.called;
+      expect(spawnSync).to.not.have.been.called;
+      return;
+    }
+    expect.fail('Expected error');
+  });
+
+  it('calls lerna to publish packages for a real version', () => {
+    const lernaBin = path.resolve(__dirname, '..', '..', '..', '..', 'node_modules', '.bin', 'lerna');
+    const packages = [
+      { name: 'packageA', version: '0.7.0' }
+    ];
+    listNpmPackages.returns(packages);
+
+    publishNpmPackages(
+      listNpmPackages,
+      markBumpedFilesAsAssumeUnchanged,
+      spawnSync
+    );
+
+    expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, true);
+    expect(spawnSync).to.have.been.calledWith(
+      lernaBin,
+      ['publish', 'from-package', '--no-changelog', '--no-push', '--exact', '--no-git-tag-version', '--force-publish', '--yes'],
+      sinon.match.any
+    );
+    expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, false);
+  });
+
+  it('reverts the assume unchanged even on spawn failure', () => {
+    const packages = [
+      { name: 'packageA', version: '0.7.0' }
+    ];
+    listNpmPackages.returns(packages);
+    spawnSync.throws(new Error('meeep'));
+
+    try {
+      publishNpmPackages(
+        listNpmPackages,
+        markBumpedFilesAsAssumeUnchanged,
+        spawnSync
+      );
+    } catch (e) {
+      expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, true);
+      expect(spawnSync).to.have.been.called;
+      expect(markBumpedFilesAsAssumeUnchanged).to.have.been.calledWith(packages, false);
+      return;
+    }
+    expect.fail('Expected error');
+  });
+});
diff --git a/packages/build/src/npm-packages/publish.ts b/packages/build/src/npm-packages/publish.ts
new file mode 100644
index 0000000000..2d9fcd0151
--- /dev/null
+++ b/packages/build/src/npm-packages/publish.ts
@@ -0,0 +1,71 @@
+import path from 'path';
+import { LERNA_BIN, PLACEHOLDER_VERSION, PROJECT_ROOT } from './constants';
+import { LernaPackageDescription, listNpmPackages as listNpmPackagesFn } from './list';
+import { spawnSync } from './spawn-sync';
+
+export function publishNpmPackages(
+  listNpmPackages: typeof listNpmPackagesFn = listNpmPackagesFn,
+  markBumpedFilesAsAssumeUnchangedFn: typeof markBumpedFilesAsAssumeUnchanged = markBumpedFilesAsAssumeUnchanged,
+  spawnSyncFn: typeof spawnSync = spawnSync
+): void {
+  const packages = listNpmPackages();
+
+  const versions = Array.from(new Set(packages.map(({ version }) => version)));
+
+  if (versions.length !== 1) {
+    throw new Error(`Refusing to publish packages with multiple versions: ${versions}`);
+  }
+
+  if (versions[0] === PLACEHOLDER_VERSION) {
+    throw new Error('Refusing to publish packages with placeholder version');
+  }
+
+  // Lerna requires a clean repository for a publish from-package (--force-publish does not have any effect here)
+  // we use git update-index --assume-unchanged on files we know have been bumped
+  markBumpedFilesAsAssumeUnchangedFn(packages, true);
+  try {
+    spawnSyncFn(LERNA_BIN, [
+      'publish',
+      'from-package',
+      '--no-changelog',
+      '--no-push',
+      '--exact',
+      '--no-git-tag-version',
+      '--force-publish',
+      '--yes'
+    ], {
+      stdio: 'inherit',
+      cwd: PROJECT_ROOT,
+      encoding: 'utf8'
+    });
+  } finally {
+    markBumpedFilesAsAssumeUnchangedFn(packages, false);
+  }
+}
+
+export function markBumpedFilesAsAssumeUnchanged(
+  packages: LernaPackageDescription[],
+  assumeUnchanged: boolean,
+  spawnSyncFn: typeof spawnSync = spawnSync
+): void {
+  const filesToAssume = [
+    path.resolve(PROJECT_ROOT, 'lerna.json')
+  ];
+  packages.forEach(({ location }) => {
+    filesToAssume.push(path.resolve(location, 'package.json'));
+    filesToAssume.push(path.resolve(location, 'package-lock.json'));
+  });
+
+  filesToAssume.forEach(f => {
+    spawnSyncFn('git', [
+      'update-index',
+      assumeUnchanged ? '--assume-unchanged' : '--no-assume-unchanged',
+      f
+    ], {
+      stdio: 'inherit',
+      cwd: PROJECT_ROOT,
+      encoding: 'utf8'
+    }, true);
+    console.info(`File ${f} is now ${assumeUnchanged ? '' : 'NOT '}assumed to be unchanged`);
+  });
+}
diff --git a/packages/build/src/npm-packages/spawn-sync.spec.ts b/packages/build/src/npm-packages/spawn-sync.spec.ts
new file mode 100644
index 0000000000..e77ae51c22
--- /dev/null
+++ b/packages/build/src/npm-packages/spawn-sync.spec.ts
@@ -0,0 +1,39 @@
+import { expect } from 'chai';
+import { spawnSync } from './spawn-sync';
+
+describe('npm-packages spawnSync', () => {
+  it('works for a valid command', () => {
+    const result = spawnSync('bash', ['-c', 'echo -n works'], { encoding: 'utf8' });
+    expect(result.status).to.equal(0);
+    expect(result.stdout).to.equal('works');
+  });
+
+  it('throws on ENOENT error', () => {
+    try {
+      spawnSync('notaprogram', [], { encoding: 'utf8' });
+    } catch (e) {
+      return expect(e).to.not.be.undefined;
+    }
+    expect.fail('Expected error');
+  });
+
+  it('throws on non-zero exit code', () => {
+    try {
+      spawnSync('bash', ['-c', 'exit 1'], { encoding: 'utf8' });
+    } catch (e) {
+      return expect(e).to.not.be.undefined;
+    }
+    expect.fail('Expected error');
+  });
+
+  it('ignores errors when asked to for ENOENT', () => {
+    const result = spawnSync('notaprogram', [], { encoding: 'utf8' }, true);
+    expect(result).to.not.be.undefined;
+  });
+
+  it('ignores errors when asked to for non-zero exit code', () => {
+    const result = spawnSync('bash', ['-c', 'exit 1'], { encoding: 'utf8' }, true);
+    expect(result).to.not.be.undefined;
+    expect(result?.status).to.equal(1);
+  });
+});
diff --git a/packages/build/src/npm-packages/spawn-sync.ts b/packages/build/src/npm-packages/spawn-sync.ts
new file mode 100644
index 0000000000..4249e6546e
--- /dev/null
+++ b/packages/build/src/npm-packages/spawn-sync.ts
@@ -0,0 +1,30 @@
+import { SpawnSyncOptionsWithStringEncoding, SpawnSyncReturns } from 'child_process';
+import * as spawn from 'cross-spawn';
+
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding): SpawnSyncReturns<string>;
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors: false): SpawnSyncReturns<string>;
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors: true): SpawnSyncReturns<string> | undefined;
+export function spawnSync(command: string, args: string[], options: SpawnSyncOptionsWithStringEncoding, ignoreErrors = false): SpawnSyncReturns<string> | undefined {
+  const result = spawn.sync(command, args, options);
+  if (result.error) {
+    console.error('spawn.sync returned error', result.error);
+    console.error(result.stdout);
+    console.error(result.stderr);
+
+    if (!ignoreErrors) {
+      throw new Error(`Failed to spawn ${command}, args: ${args.join(',')}: ${result.error}`);
+    } else {
+      console.warn('Ignoring error and continuing...');
+    }
+  } else if (result.status !== 0) {
+    console.error('spawn.sync exited with non-zero', result.status);
+    console.error(result.stdout);
+    console.error(result.stderr);
+    if (!ignoreErrors) {
+      throw new Error(`Spawn exited non-zero for ${command}, args: ${args.join(',')}: ${result.status}`);
+    } else {
+      console.warn('Ignoring error and continuing...');
+    }
+  }
+  return result;
+}