diff --git a/patches/node/.patches b/patches/node/.patches
index 0275693b13434..3ea2422035146 100644
--- a/patches/node/.patches
+++ b/patches/node/.patches
@@ -35,3 +35,4 @@ fix_handle_new_tostring_behavior_in_v8_serdes_test.patch
 node-api_faster_threadsafe_function.patch
 src_remove_extra_semi_after_member_fn.patch
 errors_refactor_to_use_more_primordials.patch
+repl_fix_crash_when_sharedarraybuffer_disabled.patch
diff --git a/patches/node/repl_fix_crash_when_sharedarraybuffer_disabled.patch b/patches/node/repl_fix_crash_when_sharedarraybuffer_disabled.patch
new file mode 100644
index 0000000000000..93dbc8ceb3fc9
--- /dev/null
+++ b/patches/node/repl_fix_crash_when_sharedarraybuffer_disabled.patch
@@ -0,0 +1,54 @@
+From 0000000000000000000000000000000000000000 Mon Sep 17 00:00:00 2001
+From: Shelley Vohr <shelley.vohr@gmail.com>
+Date: Mon, 9 Aug 2021 18:42:15 +0200
+Subject: repl: fix crash when SharedArrayBuffer disabled
+
+It's possible for SharedArrayBuffers to be disabled with
+--no-harmony-sharedarraybuffer so we first need to check that this
+isn't the case before attempting to use them in the repl or a crash occurs.
+
+Upstreamed at https://github.com/nodejs/node/pull/39718.
+
+diff --git a/benchmark/worker/atomics-wait.js b/benchmark/worker/atomics-wait.js
+index a771b1813731edf4f0dd60f3505799e389f1d876..b9461677e2d7d1df192e752496e62cca837717b5 100644
+--- a/benchmark/worker/atomics-wait.js
++++ b/benchmark/worker/atomics-wait.js
+@@ -7,6 +7,10 @@ const bench = common.createBenchmark(main, {
+ });
+ 
+ function main({ n }) {
++  if (typeof SharedArrayBuffer === 'undefined') {
++    throw new Error('SharedArrayBuffers must be enabled to run this benchmark');
++  }
++
+   const i32arr = new Int32Array(new SharedArrayBuffer(4));
+   bench.start();
+   for (let i = 0; i < n; i++)
+diff --git a/lib/internal/main/worker_thread.js b/lib/internal/main/worker_thread.js
+index 6f8cb6b942b5f295e6195e18059736df4bff8756..a2faa5c4a12f3af84dbfc4a3e4485d4ee5ce0167 100644
+--- a/lib/internal/main/worker_thread.js
++++ b/lib/internal/main/worker_thread.js
+@@ -132,6 +132,9 @@ port.on('message', (message) => {
+     const originalCwd = process.cwd;
+ 
+     process.cwd = function() {
++      // SharedArrayBuffers can be disabled with --no-harmony-sharedarraybuffer.
++      if (typeof SharedArrayBuffer === 'undefined') return originalCwd();
++
+       const currentCounter = Atomics.load(cwdCounter, 0);
+       if (currentCounter === lastCounter)
+         return cachedCwd;
+diff --git a/lib/internal/worker.js b/lib/internal/worker.js
+index d38649c7fb158361096d5a7a3b5bd629ba7b6d0b..468e85cacb09f3e4b3dd5603d5f54a010c7ff751 100644
+--- a/lib/internal/worker.js
++++ b/lib/internal/worker.js
+@@ -81,7 +81,8 @@ let debug = require('internal/util/debuglog').debuglog('worker', (fn) => {
+ 
+ let cwdCounter;
+ 
+-if (isMainThread) {
++// SharedArrayBuffers can be disabled with --no-harmony-sharedarraybuffer.
++if (isMainThread && typeof SharedArrayBuffer !== 'undefined') {
+   cwdCounter = new Uint32Array(new SharedArrayBuffer(4));
+   const originalChdir = process.chdir;
+   process.chdir = function(path) {