diff --git a/lib/audit.js b/lib/audit.js
index e77beab1eff61..cb8ab5b3a43f5 100644
--- a/lib/audit.js
+++ b/lib/audit.js
@@ -2,7 +2,7 @@ const Arborist = require('@npmcli/arborist')
 const auditReport = require('npm-audit-report')
 const npm = require('./npm.js')
 const output = require('./utils/output.js')
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 const auditError = require('./utils/audit-error.js')
 
 const audit = async args => {
@@ -14,7 +14,7 @@ const audit = async args => {
   const fix = args[0] === 'fix'
   await arb.audit({ fix })
   if (fix)
-    reifyOutput(arb)
+    await reifyFinish(arb)
   else {
     // will throw if there's an error, because this is an audit command
     auditError(arb.auditReport)
diff --git a/lib/ci.js b/lib/ci.js
index a1632e7e98064..1255fbc2646fd 100644
--- a/lib/ci.js
+++ b/lib/ci.js
@@ -1,7 +1,7 @@
 const util = require('util')
 const Arborist = require('@npmcli/arborist')
 const rimraf = util.promisify(require('rimraf'))
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 
 const log = require('npmlog')
 const npm = require('./npm.js')
@@ -35,7 +35,7 @@ const ci = async () => {
   ])
   // npm ci should never modify the lockfile or package.json
   await arb.reify({ ...npm.flatOptions, save: false })
-  reifyOutput(arb)
+  await reifyFinish(arb)
 }
 
 module.exports = Object.assign(cmd, { completion, usage })
diff --git a/lib/dedupe.js b/lib/dedupe.js
index a08c9f3f8f334..fe8243e21e43d 100644
--- a/lib/dedupe.js
+++ b/lib/dedupe.js
@@ -2,7 +2,7 @@
 const npm = require('./npm.js')
 const Arborist = require('@npmcli/arborist')
 const usageUtil = require('./utils/usage.js')
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 
 const usage = usageUtil('dedupe', 'npm dedupe')
 const completion = require('./utils/completion/none.js')
@@ -18,7 +18,7 @@ const dedupe = async (args) => {
     dryRun,
   })
   await arb.dedupe(npm.flatOptions)
-  reifyOutput(arb)
+  await reifyFinish(arb)
 }
 
 module.exports = Object.assign(cmd, { usage, completion })
diff --git a/lib/install.js b/lib/install.js
index 5f04fcd4f9d6b..f621c85c23e1e 100644
--- a/lib/install.js
+++ b/lib/install.js
@@ -6,13 +6,15 @@ const util = require('util')
 const readdir = util.promisify(fs.readdir)
 const npm = require('./npm.js')
 const usageUtil = require('./utils/usage.js')
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 const log = require('npmlog')
 const { resolve, join } = require('path')
 const Arborist = require('@npmcli/arborist')
 const runScript = require('@npmcli/run-script')
 
-const install = async (args, cb) => {
+const cmd = async (args, cb) => install(args).then(() => cb()).catch(cb)
+
+const install = async args => {
   // the /path/to/node_modules/..
   const globalTop = resolve(npm.globalDir, '..')
   const { ignoreScripts, global: isGlobalInstall } = npm.flatOptions
@@ -34,38 +36,33 @@ const install = async (args, cb) => {
     path: where,
   })
 
-  try {
-    await arb.reify({
-      ...npm.flatOptions,
-      add: args,
-    })
-    if (!args.length && !isGlobalInstall && !ignoreScripts) {
-      const { scriptShell } = npm.flatOptions
-      const scripts = [
-        'preinstall',
-        'install',
-        'postinstall',
-        'prepublish', // XXX should we remove this finally??
-        'preprepare',
-        'prepare',
-        'postprepare',
-      ]
-      for (const event of scripts) {
-        await runScript({
-          path: where,
-          args: [],
-          scriptShell,
-          stdio: 'inherit',
-          stdioString: true,
-          event,
-        })
-      }
+  await arb.reify({
+    ...npm.flatOptions,
+    add: args,
+  })
+  if (!args.length && !isGlobalInstall && !ignoreScripts) {
+    const { scriptShell } = npm.flatOptions
+    const scripts = [
+      'preinstall',
+      'install',
+      'postinstall',
+      'prepublish', // XXX should we remove this finally??
+      'preprepare',
+      'prepare',
+      'postprepare',
+    ]
+    for (const event of scripts) {
+      await runScript({
+        path: where,
+        args: [],
+        scriptShell,
+        stdio: 'inherit',
+        stdioString: true,
+        event,
+      })
     }
-    reifyOutput(arb)
-    cb()
-  } catch (er) {
-    cb(er)
   }
+  await reifyFinish(arb)
 }
 
 const usage = usageUtil(
@@ -144,4 +141,4 @@ const completion = async (opts, cb) => {
   cb()
 }
 
-module.exports = Object.assign(install, { usage, completion })
+module.exports = Object.assign(cmd, { usage, completion })
diff --git a/lib/link.js b/lib/link.js
index d7303fd086cdd..bee44d43a7ff6 100644
--- a/lib/link.js
+++ b/lib/link.js
@@ -10,7 +10,7 @@ const semver = require('semver')
 
 const npm = require('./npm.js')
 const usageUtil = require('./utils/usage.js')
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 
 const completion = (opts, cb) => {
   const dir = npm.globalDir
@@ -122,7 +122,7 @@ const linkInstall = async args => {
     add: names.map(l => `file:${resolve(globalTop, 'node_modules', l)}`),
   })
 
-  reifyOutput(localArb)
+  await reifyFinish(localArb)
 }
 
 const linkPkg = async () => {
@@ -133,7 +133,7 @@ const linkPkg = async () => {
     global: true,
   })
   await arb.reify({ add: [`file:${npm.prefix}`] })
-  reifyOutput(arb)
+  await reifyFinish(arb)
 }
 
 module.exports = Object.assign(cmd, { completion, usage })
diff --git a/lib/prune.js b/lib/prune.js
index aa2ed378088e3..ea6ed4108aba2 100644
--- a/lib/prune.js
+++ b/lib/prune.js
@@ -3,7 +3,7 @@ const npm = require('./npm.js')
 const Arborist = require('@npmcli/arborist')
 const usageUtil = require('./utils/usage.js')
 
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 
 const usage = usageUtil('prune',
   'npm prune [[<@scope>/]<pkg>...] [--production]'
@@ -19,7 +19,7 @@ const prune = async () => {
     path: where,
   })
   await arb.prune(npm.flatOptions)
-  reifyOutput(arb)
+  await reifyFinish(arb)
 }
 
 module.exports = Object.assign(cmd, { usage, completion })
diff --git a/lib/uninstall.js b/lib/uninstall.js
index ec997ae6457ab..dbaa992f500e0 100644
--- a/lib/uninstall.js
+++ b/lib/uninstall.js
@@ -5,7 +5,7 @@ const npm = require('./npm.js')
 const rpj = require('read-package-json-fast')
 const { resolve } = require('path')
 const usageUtil = require('./utils/usage.js')
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 
 const cmd = (args, cb) => rm(args).then(() => cb()).catch(cb)
 
@@ -32,7 +32,7 @@ const rm = async args => {
     ...npm.flatOptions,
     rm: args,
   })
-  reifyOutput(arb)
+  await reifyFinish(arb)
 }
 
 const usage = usageUtil(
diff --git a/lib/update.js b/lib/update.js
index 791e67e407643..0a786e30f312e 100644
--- a/lib/update.js
+++ b/lib/update.js
@@ -4,7 +4,7 @@ const Arborist = require('@npmcli/arborist')
 const log = require('npmlog')
 const npm = require('./npm.js')
 const usageUtil = require('./utils/usage.js')
-const reifyOutput = require('./utils/reify-output.js')
+const reifyFinish = require('./utils/reify-finish.js')
 const completion = require('./utils/completion/installed-deep.js')
 
 const usage = usageUtil(
@@ -32,7 +32,7 @@ const update = async args => {
   })
 
   await arb.reify({ update })
-  reifyOutput(arb)
+  await reifyFinish(arb)
 }
 
 module.exports = Object.assign(cmd, { usage, completion })
diff --git a/lib/utils/reify-finish.js b/lib/utils/reify-finish.js
new file mode 100644
index 0000000000000..76dba06cb570c
--- /dev/null
+++ b/lib/utils/reify-finish.js
@@ -0,0 +1,31 @@
+const reifyOutput = require('./reify-output.js')
+const npm = require('../npm.js')
+const ini = require('ini')
+const {writeFile} = require('fs').promises
+const {resolve} = require('path')
+
+const reifyFinish = async arb => {
+  await saveBuiltinConfig(arb)
+  reifyOutput(arb)
+}
+
+const saveBuiltinConfig = async arb => {
+  const { options: { global }, actualTree } = arb
+  if (!global)
+    return
+
+  // if we are using a builtin config, and just installed npm as
+  // a top-level global package, we have to preserve that config.
+  const npmNode = actualTree.inventory.get('node_modules/npm')
+  if (!npmNode)
+    return
+
+  const builtinConf = npm.config.data.get('builtin')
+  if (builtinConf.loadError)
+    return
+
+  const content = ini.stringify(builtinConf.raw).trim() + '\n'
+  await writeFile(resolve(npmNode.path, 'npmrc'), content)
+}
+
+module.exports = reifyFinish
diff --git a/tap-snapshots/test-lib-utils-reify-finish.js-TAP.test.js b/tap-snapshots/test-lib-utils-reify-finish.js-TAP.test.js
new file mode 100644
index 0000000000000..a82905a399679
--- /dev/null
+++ b/tap-snapshots/test-lib-utils-reify-finish.js-TAP.test.js
@@ -0,0 +1,15 @@
+/* IMPORTANT
+ * This snapshot file is auto-generated, but designed for humans.
+ * It should be checked into source control and tracked carefully.
+ * Re-generate by setting TAP_SNAPSHOT=1 and running tests.
+ * Make sure to inspect the output below.  Do not ignore changes!
+ */
+'use strict'
+exports[`test/lib/utils/reify-finish.js TAP should write if everything above passes > written config 1`] = `
+hasBuiltinConfig=true
+x=y
+
+[nested]
+foo=bar
+
+`
diff --git a/test/lib/audit.js b/test/lib/audit.js
index 4918cb2fc2711..723675c3233d7 100644
--- a/test/lib/audit.js
+++ b/test/lib/audit.js
@@ -5,7 +5,7 @@ const audit = require('../../lib/audit.js')
 t.test('should audit using Arborist', t => {
   let ARB_ARGS = null
   let AUDIT_CALLED = false
-  let REIFY_OUTPUT_CALLED = false
+  let REIFY_FINISH_CALLED = false
   let AUDIT_REPORT_CALLED = false
   let OUTPUT_CALLED = false
   let ARB_OBJ = null
@@ -32,11 +32,11 @@ t.test('should audit using Arborist', t => {
         this.auditReport = {}
       }
     },
-    '../../lib/utils/reify-output.js': arb => {
+    '../../lib/utils/reify-finish.js': arb => {
       if (arb !== ARB_OBJ) {
         throw new Error('got wrong object passed to reify-output')
       }
-      REIFY_OUTPUT_CALLED = true
+      REIFY_FINISH_CALLED = true
     },
     '../../lib/utils/output.js': () => {
       OUTPUT_CALLED = true
@@ -55,7 +55,7 @@ t.test('should audit using Arborist', t => {
 
   t.test('audit fix', t => {
     audit(['fix'], () => {
-      t.equal(REIFY_OUTPUT_CALLED, true, 'called reify output')
+      t.equal(REIFY_FINISH_CALLED, true, 'called reify output')
       t.end()
     })
   })
diff --git a/test/lib/utils/reify-finish.js b/test/lib/utils/reify-finish.js
new file mode 100644
index 0000000000000..c19956f0b2557
--- /dev/null
+++ b/test/lib/utils/reify-finish.js
@@ -0,0 +1,78 @@
+const t = require('tap')
+const requireInject = require('require-inject')
+
+const npm = {
+  config: {
+    data: {
+      get: () => builtinConfMock,
+    },
+  },
+}
+
+const builtinConfMock = {
+  loadError: new Error('no builtin config'),
+  raw: { hasBuiltinConfig: true, x: 'y', nested: { foo: 'bar' }},
+}
+
+const reifyOutput = () => {}
+
+let expectWrite = false
+const realFs = require('fs')
+const fs = {
+  ...realFs,
+  promises: {
+    ...realFs.promises,
+    writeFile: async (path, data) => {
+      if (!expectWrite)
+        throw new Error('did not expect to write builtin config file')
+      return realFs.promises.writeFile(path, data)
+    },
+  },
+}
+
+const reifyFinish = requireInject('../../../lib/utils/reify-finish.js', {
+  fs,
+  '../../../lib/npm.js': npm,
+  '../../../lib/utils/reify-output.js': reifyOutput,
+})
+
+t.test('should not write if not global', async t => {
+  expectWrite = false
+  await reifyFinish({
+    options: { global: false },
+    actualTree: {},
+  })
+})
+
+t.test('should not write if no global npm module', async t => {
+  expectWrite = false
+  await reifyFinish({
+    options: { global: true },
+    actualTree: {
+      inventory: new Map(),
+    },
+  })
+})
+
+t.test('should not write if builtin conf had load error', async t => {
+  expectWrite = false
+  await reifyFinish({
+    options: { global: true },
+    actualTree: {
+      inventory: new Map([['node_modules/npm', {}]]),
+    },
+  })
+})
+
+t.test('should write if everything above passes', async t => {
+  expectWrite = true
+  delete builtinConfMock.loadError
+  const path = t.testdir()
+  await reifyFinish({
+    options: { global: true },
+    actualTree: {
+      inventory: new Map([['node_modules/npm', {path}]]),
+    },
+  })
+  t.matchSnapshot(fs.readFileSync(`${path}/npmrc`, 'utf8'), 'written config')
+})