diff --git a/test/built-ins/Atomics/waitAsync/false-for-timeout-agent.js b/test/built-ins/Atomics/waitAsync/false-for-timeout-agent.js
index bc733dda98..0b274263cb 100644
--- a/test/built-ins/Atomics/waitAsync/false-for-timeout-agent.js
+++ b/test/built-ins/Atomics/waitAsync/false-for-timeout-agent.js
@@ -14,6 +14,7 @@ info: |
 
   6. Let q be ? ToNumber(timeout).
 
+flags: [async]
 includes: [atomicsHelper.js]
 features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
 ---*/
@@ -48,40 +49,43 @@ $262.agent.start(`
 const i32a = new Int32Array(
   new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
 );
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
 
-$262.agent.safeBroadcast(i32a);
-$262.agent.waitUntil(i32a, RUNNING, 1);
-$262.agent.tryYield();
+  assert.sameValue(agentCount, 1);
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, false).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, false).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+}).then($DONE, $DONE);
 
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, false).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, false).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
-);
 
-assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
diff --git a/test/built-ins/Atomics/waitAsync/nan-for-timeout.js b/test/built-ins/Atomics/waitAsync/nan-for-timeout-agent.js
similarity index 71%
rename from test/built-ins/Atomics/waitAsync/nan-for-timeout.js
rename to test/built-ins/Atomics/waitAsync/nan-for-timeout-agent.js
index d3d82a2352..2455694fe5 100644
--- a/test/built-ins/Atomics/waitAsync/nan-for-timeout.js
+++ b/test/built-ins/Atomics/waitAsync/nan-for-timeout-agent.js
@@ -14,6 +14,7 @@ info: |
 
   6. Let q be ? ToNumber(timeout).
 
+flags: [async]
 includes: [atomicsHelper.js]
 features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
 ---*/
@@ -34,9 +35,18 @@ const i32a = new Int32Array(
   new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
 );
 
-$262.agent.safeBroadcast(i32a);
-$262.agent.waitUntil(i32a, RUNNING, 1);
-$262.agent.tryYield();
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1);
+
+  assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(i32a, 0) returns 1');
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'ok',
+    'await Atomics.waitAsync(i32a, 0, 0, NaN).value resolves to "ok"'
+  );
+
+}).then($DONE, $DONE);
+
 
-assert.sameValue(Atomics.notify(i32a, 0), 1, 'Atomics.notify(i32a, 0) returns 1');
-assert.sameValue($262.agent.getReport(), "ok", 'await Atomics.waitAsync(i32a, 0, 0, NaN).value resolves to "ok"');
diff --git a/test/built-ins/Atomics/waitAsync/negative-timeout-agent.js b/test/built-ins/Atomics/waitAsync/negative-timeout-agent.js
index 6244fcc1ba..e3fa5ae14f 100644
--- a/test/built-ins/Atomics/waitAsync/negative-timeout-agent.js
+++ b/test/built-ins/Atomics/waitAsync/negative-timeout-agent.js
@@ -5,6 +5,16 @@
 esid: sec-atomics.waitasync
 description: >
   Test that Atomics.waitAsync times out with a negative timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
 includes: [atomicsHelper.js]
 features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
 ---*/
@@ -15,7 +25,7 @@ $262.agent.start(`
   $262.agent.receiveBroadcast(async (sab) => {
     var i32a = new Int32Array(sab);
     Atomics.add(i32a, ${RUNNING}, 1);
-    $262.agent.report(await Atomics.waitSync(i32a, 0, 0, -5).value); // -5 => 0
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, -5).value); // -5 => 0
     $262.agent.leaving();
   });
 `);
@@ -24,15 +34,17 @@ const i32a = new Int32Array(
   new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
 );
 
-$262.agent.safeBroadcast(i32a);
-$262.agent.waitUntil(i32a, RUNNING, 1);
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
 
-// Try to yield control to ensure the agent actually started to wait.
-$262.agent.tryYield();
+  assert.sameValue(agentCount, 1);
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, -5).value resolves to "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+}).then($DONE, $DONE);
 
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitSync(i32a, 0, 0, -5).value resolves to "timed-out"'
-);
-assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
diff --git a/test/built-ins/Atomics/waitAsync/negative-timeout.js b/test/built-ins/Atomics/waitAsync/negative-timeout.js
index 0776ca54e5..9f365e9e46 100644
--- a/test/built-ins/Atomics/waitAsync/negative-timeout.js
+++ b/test/built-ins/Atomics/waitAsync/negative-timeout.js
@@ -5,6 +5,15 @@
 esid: sec-atomics.waitasync
 description: >
   Test that Atomics.waitAsync times out with a negative timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
 flags: [async]
 features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
 ---*/
diff --git a/test/built-ins/Atomics/waitAsync/null-for-timeout-agent.js b/test/built-ins/Atomics/waitAsync/null-for-timeout-agent.js
index 1e515ab14e..cebece1527 100644
--- a/test/built-ins/Atomics/waitAsync/null-for-timeout-agent.js
+++ b/test/built-ins/Atomics/waitAsync/null-for-timeout-agent.js
@@ -8,10 +8,15 @@ description: >
 info: |
   Atomics.waitAsync( typedArray, index, value, timeout )
 
-  4. Let q be ? ToNumber(timeout).
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
 
     Null -> Return +0.
 
+flags: [async]
 includes: [atomicsHelper.js]
 features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
 ---*/
@@ -48,41 +53,41 @@ const i32a = new Int32Array(
   new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
 );
 
-$262.agent.safeBroadcast(i32a);
-$262.agent.waitUntil(i32a, RUNNING, 1);
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+  assert.sameValue(agentCount, 1);
 
-// Try to yield control to ensure the agent actually started to wait.
-$262.agent.tryYield();
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, null).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, null).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
+  );
 
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, null).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, null).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
-);
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+}).then($DONE, $DONE);
 
-assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
diff --git a/test/built-ins/Atomics/waitAsync/null-for-timeout.js b/test/built-ins/Atomics/waitAsync/null-for-timeout.js
index cc4d369f49..34b8f06bc4 100644
--- a/test/built-ins/Atomics/waitAsync/null-for-timeout.js
+++ b/test/built-ins/Atomics/waitAsync/null-for-timeout.js
@@ -8,7 +8,11 @@ description: >
 info: |
   Atomics.waitAsync( typedArray, index, value, timeout )
 
-  4. Let q be ? ToNumber(timeout).
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
 
     Null -> Return +0.
 
diff --git a/test/built-ins/Atomics/waitAsync/object-for-timeout-agent.js b/test/built-ins/Atomics/waitAsync/object-for-timeout-agent.js
index b5da2cd39e..41cd565b19 100644
--- a/test/built-ins/Atomics/waitAsync/object-for-timeout-agent.js
+++ b/test/built-ins/Atomics/waitAsync/object-for-timeout-agent.js
@@ -4,14 +4,22 @@
 /*---
 esid: sec-atomics.waitasync
 description: >
-  False timeout arg should result in an +0 timeout
+  Object valueOf, toString, toPrimitive Zero timeout arg should result in an +0 timeout
 info: |
-  Atomics.wait( typedArray, index, value, timeout )
+  Atomics.waitAsync( typedArray, index, value, timeout )
 
-  4. Let q be ? ToNumber(timeout).
+  1. Return DoWait(async, typedArray, index, value, timeout).
 
-    Null -> Return +0.
+  DoWait ( mode, typedArray, index, value, timeout )
 
+  6. Let q be ? ToNumber(timeout).
+
+    Object -> Apply the following steps:
+
+      Let primValue be ? ToPrimitive(argument, hint Number).
+      Return ? ToNumber(primValue).
+
+flags: [async]
 includes: [atomicsHelper.js]
 features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
 ---*/
@@ -53,41 +61,42 @@ const i32a = new Int32Array(
   new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
 );
 
-$262.agent.safeBroadcast(i32a);
-$262.agent.waitUntil(i32a, RUNNING, 1);
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
 
-// Try to yield control to ensure the agent actually started to wait.
-$262.agent.tryYield();
+  assert.sameValue(agentCount, 1);
 
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, toString).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, toString).value resolves to "timed-out"'
-);
-assert.sameValue(
-  $262.agent.getReport(),
-  'timed-out',
-  'Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
-);
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, toString).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, toString).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+}).then($DONE, $DONE);
 
-assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
diff --git a/test/built-ins/Atomics/waitAsync/object-for-timeout.js b/test/built-ins/Atomics/waitAsync/object-for-timeout.js
index 207f6bfde6..d4b0f561e5 100644
--- a/test/built-ins/Atomics/waitAsync/object-for-timeout.js
+++ b/test/built-ins/Atomics/waitAsync/object-for-timeout.js
@@ -4,11 +4,15 @@
 /*---
 esid: sec-atomics.waitasync
 description: >
-  Throws a TypeError if index arg can not be converted to an Integer
+  Object valueOf, toString, toPrimitive Zero timeout arg should result in an +0 timeout
 info: |
-  Atomics.wait( typedArray, index, value, timeout )
+  Atomics.waitAsync( typedArray, index, value, timeout )
 
-  4. Let q be ? ToNumber(timeout).
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
 
     Object -> Apply the following steps:
 
diff --git a/test/built-ins/Atomics/waitAsync/true-for-timeout-agent.js b/test/built-ins/Atomics/waitAsync/true-for-timeout-agent.js
new file mode 100644
index 0000000000..c45c57494a
--- /dev/null
+++ b/test/built-ins/Atomics/waitAsync/true-for-timeout-agent.js
@@ -0,0 +1,73 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  True timeout arg should result in an +0 timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
+---*/
+const RUNNING = 1;
+
+$262.agent.start(`
+  const valueOf = {
+    valueOf() {
+      return true;
+    }
+  };
+
+  const toPrimitive = {
+    [Symbol.toPrimitive]() {
+      return true;
+    }
+  };
+
+  $262.agent.receiveBroadcast(async (sab) => {
+    const i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, true).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, valueOf).value);
+    $262.agent.report(await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value);
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+$262.agent.safeBroadcastAsync(i32a, RUNNING, 1).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, 1);
+
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, false).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, valueOf).value resolves to "timed-out"'
+  );
+  assert.sameValue(
+    await $262.agent.getReportAsync(),
+    'timed-out',
+    'await Atomics.waitAsync(i32a, 0, 0, toPrimitive).value resolves to "timed-out"'
+  );
+
+  assert.sameValue(Atomics.notify(i32a, 0), 0, 'Atomics.notify(i32a, 0) returns 0');
+
+}).then($DONE, $DONE);
+
+
diff --git a/test/built-ins/Atomics/waitAsync/true-for-timeout.js b/test/built-ins/Atomics/waitAsync/true-for-timeout.js
new file mode 100644
index 0000000000..542fa01227
--- /dev/null
+++ b/test/built-ins/Atomics/waitAsync/true-for-timeout.js
@@ -0,0 +1,47 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Throws a TypeError if index arg can not be converted to an Integer
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+
+    Boolean -> If argument is true, return 1. If argument is false, return +0.
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
+---*/
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+const valueOf = {
+  valueOf() {
+    return true;
+  }
+};
+
+const toPrimitive = {
+  [Symbol.toPrimitive]() {
+    return true;
+  }
+};
+
+Promise.all([
+    Atomics.waitAsync(i32a, 0, 0, true).value,
+    Atomics.waitAsync(i32a, 0, 0, valueOf).value,
+    Atomics.waitAsync(i32a, 0, 0, toPrimitive).value,
+  ]).then(outcomes => {
+    assert.sameValue(outcomes[0], 'timed-out');
+    assert.sameValue(outcomes[0], 'timed-out');
+    assert.sameValue(outcomes[0], 'timed-out');
+  }, $DONE).then($DONE, $DONE);
diff --git a/test/built-ins/Atomics/waitAsync/undefined-for-timeout-agent.js b/test/built-ins/Atomics/waitAsync/undefined-for-timeout-agent.js
new file mode 100644
index 0000000000..a70c1b2d04
--- /dev/null
+++ b/test/built-ins/Atomics/waitAsync/undefined-for-timeout-agent.js
@@ -0,0 +1,75 @@
+// Copyright (C) 2020 Rick Waldron. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-atomics.waitasync
+description: >
+  Undefined timeout arg should result in an infinite timeout
+info: |
+  Atomics.waitAsync( typedArray, index, value, timeout )
+
+  1. Return DoWait(async, typedArray, index, value, timeout).
+
+  DoWait ( mode, typedArray, index, value, timeout )
+
+  6. Let q be ? ToNumber(timeout).
+    ...
+    Undefined    Return NaN.
+
+  5.If q is NaN, let t be +∞, else let t be max(q, 0)
+
+flags: [async]
+includes: [atomicsHelper.js]
+features: [Atomics.waitAsync, SharedArrayBuffer, TypedArray, Atomics]
+---*/
+
+const WAIT_INDEX = 0;
+const RUNNING = 1;
+const NUMAGENT = 2;
+const NOTIFYCOUNT = 2;
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // undefined => NaN => +Infinity
+    $262.agent.report("A " + (await Atomics.waitAsync(i32a, 0, 0, undefined).value));
+    $262.agent.leaving();
+  });
+`);
+
+$262.agent.start(`
+  $262.agent.receiveBroadcast(async (sab) => {
+    var i32a = new Int32Array(sab);
+    Atomics.add(i32a, ${RUNNING}, 1);
+
+    // undefined timeout arg => NaN => +Infinity
+    $262.agent.report("B " + (await Atomics.waitAsync(i32a, 0, 0).value));
+    $262.agent.leaving();
+  });
+`);
+
+const i32a = new Int32Array(
+  new SharedArrayBuffer(Int32Array.BYTES_PER_ELEMENT * 4)
+);
+
+$262.agent.safeBroadcastAsync(i32a, RUNNING, NUMAGENT).then(async (agentCount) => {
+
+  assert.sameValue(agentCount, NUMAGENT);
+
+  assert.sameValue(
+    Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT),
+    NOTIFYCOUNT,
+    'Atomics.notify(i32a, WAIT_INDEX, NOTIFYCOUNT) returns the value of `NOTIFYCOUNT` (2)'
+  );
+
+  Promise.all([
+    $262.agent.getReportAsync(),
+    $262.agent.getReportAsync(),
+  ]).then(reports => {
+    reports.sort();
+    assert.sameValue(reports[0], 'A ok', 'The value of reports[0] is "A ok"');
+    assert.sameValue(reports[1], 'B ok', 'The value of reports[1] is "B ok"');
+  }).then($DONE, $DONE);
+}).then($DONE, $DONE);