diff --git a/test/built-ins/Temporal/Duration/prototype/toJSON/basic.js b/test/built-ins/Temporal/Duration/prototype/toJSON/basic.js
new file mode 100644
index 00000000000..8cadc51661c
--- /dev/null
+++ b/test/built-ins/Temporal/Duration/prototype/toJSON/basic.js
@@ -0,0 +1,240 @@
+// Copyright (C) 2021 the V8 project authors. All rights reserved.
+// This code is governed by the BSD license found in the LICENSE file.
+
+/*---
+esid: sec-temporal.duration.prototype.tojson
+description: Temporal.Duration.prototype.toJSON will return correct iso8601 string for the given duration.
+info: |
+  1. Let duration be the this value.
+  2. Perform ? RequireInternalSlot(duration, [[InitializedTemporalDuration]]).
+  3. Return ! TemporalDurationToString(duration.[[Years]], duration.[[Months]], duration.[[Weeks]], duration.[[Days]], duration.[[Hours]], duration.[[Minutes]], duration.[[Seconds]], duration.[[Milliseconds]], duration.[[Microseconds]], duration.[[Nanoseconds]], "auto").
+features: [Temporal]
+---*/
+
+let d = new Temporal.Duration();
+assert.sameValue(d.toJSON(), "PT0S", "zero duration");
+
+d = new Temporal.Duration(1);
+assert.sameValue(d.toJSON(), "P1Y", "positive small years");
+d = new Temporal.Duration(-1);
+assert.sameValue(d.toJSON(), "-P1Y", "negative small years");
+d = new Temporal.Duration(1234567890);
+assert.sameValue(d.toJSON(), "P1234567890Y", "positive large years");
+d = new Temporal.Duration(-1234567890);
+assert.sameValue(d.toJSON(), "-P1234567890Y", "negative large years");
+
+d = new Temporal.Duration(1, 2);
+assert.sameValue(d.toJSON(), "P1Y2M", "positive years and months");
+d = new Temporal.Duration(-1, -2);
+assert.sameValue(d.toJSON(), "-P1Y2M", "negative years and months");
+d = new Temporal.Duration(0, 2);
+assert.sameValue(d.toJSON(), "P2M", "positive small months");
+d = new Temporal.Duration(0,-2);
+assert.sameValue(d.toJSON(), "-P2M", "negative small months");
+d = new Temporal.Duration(0, 1234567890);
+assert.sameValue(d.toJSON(), "P1234567890M", "positive large months");
+d = new Temporal.Duration(0,-1234567890);
+assert.sameValue(d.toJSON(), "-P1234567890M", "negative large months");
+
+d = new Temporal.Duration(1, 2, 3);
+assert.sameValue(d.toJSON(), "P1Y2M3W", "positive years, months, weeks");
+d = new Temporal.Duration(-1, -2, -3);
+assert.sameValue(d.toJSON(), "-P1Y2M3W", "negative years, months, weeks");
+d = new Temporal.Duration(0, 0, 3);
+assert.sameValue(d.toJSON(), "P3W", "positive small weeks");
+d = new Temporal.Duration(0, 0, -3);
+assert.sameValue(d.toJSON(), "-P3W", "negative small weeks");
+d = new Temporal.Duration(1, 0, 3);
+assert.sameValue(d.toJSON(), "P1Y3W", "positive years and weeks");
+d = new Temporal.Duration(-1, 0, -3);
+assert.sameValue(d.toJSON(), "-P1Y3W", "negative years and weeks");
+d = new Temporal.Duration(0, 2, 3);
+assert.sameValue(d.toJSON(), "P2M3W", "positive months and weeks");
+d = new Temporal.Duration(0, -2, -3);
+assert.sameValue(d.toJSON(), "-P2M3W", "negative months and weeks");
+d = new Temporal.Duration(0, 0, 1234567890);
+assert.sameValue(d.toJSON(), "P1234567890W", "positive large weeks");
+d = new Temporal.Duration(0, 0, -1234567890);
+assert.sameValue(d.toJSON(), "-P1234567890W", "negative large weeks");
+
+d = new Temporal.Duration(1, 2, 3, 4);
+assert.sameValue(d.toJSON(), "P1Y2M3W4D", "positive years, months, weeks, days");
+d = new Temporal.Duration(-1, -2, -3, -4);
+assert.sameValue(d.toJSON(), "-P1Y2M3W4D", "negative years, months, weeks, days");
+d = new Temporal.Duration(0, 0, 0, 1234567890);
+assert.sameValue(d.toJSON(), "P1234567890D", "positive large days");
+d = new Temporal.Duration(0, 0, 0, -1234567890);
+assert.sameValue(d.toJSON(), "-P1234567890D", "negative large days");
+d = new Temporal.Duration(0, 0, 0, 4);
+assert.sameValue(d.toJSON(), "P4D", "positive small days");
+d = new Temporal.Duration(0, 0, 0, -4);
+assert.sameValue(d.toJSON(), "-P4D", "negative small days");
+d = new Temporal.Duration(1, 0, 0, 4);
+assert.sameValue(d.toJSON(), "P1Y4D", "positive years and days");
+d = new Temporal.Duration(-1, 0, 0, -4);
+assert.sameValue(d.toJSON(), "-P1Y4D", "negative years and days");
+d = new Temporal.Duration(0, 2, 0, 4);
+assert.sameValue(d.toJSON(), "P2M4D", "positive months and days");
+d = new Temporal.Duration(0, -2, 0, -4);
+assert.sameValue(d.toJSON(), "-P2M4D", "negative months and days");
+d = new Temporal.Duration(0, 0, 3, 4);
+assert.sameValue(d.toJSON(), "P3W4D", "positive weeks and days");
+d = new Temporal.Duration(0, 0, -3, -4);
+assert.sameValue(d.toJSON(), "-P3W4D", "negative weeks and days");
+
+d = new Temporal.Duration(0, 0, 0, 0, 5);
+assert.sameValue(d.toJSON(), "PT5H", "positive hours");
+d = new Temporal.Duration(0, 0, 0, 0, -5);
+assert.sameValue(d.toJSON(), "-PT5H", "negative hours");
+d = new Temporal.Duration(1, 0, 0, 0, 5);
+assert.sameValue(d.toJSON(), "P1YT5H", "positive years and hours");
+d = new Temporal.Duration(-1, 0, 0, 0, -5);
+assert.sameValue(d.toJSON(), "-P1YT5H", "negative years and hours");
+d = new Temporal.Duration(0, 2, 0, 0, 5);
+assert.sameValue(d.toJSON(), "P2MT5H", "positive months and hours");
+d = new Temporal.Duration(0, -2, 0, 0, -5);
+assert.sameValue(d.toJSON(), "-P2MT5H", "negative months and hours");
+
+d = new Temporal.Duration(0, 0, 0, 0, 0, 6);
+assert.sameValue(d.toJSON(), "PT6M", "positive minutes");
+d = new Temporal.Duration(0, 0, 0, 0, 0, -6);
+assert.sameValue(d.toJSON(), "-PT6M", "negative minutes");
+d = new Temporal.Duration(0, 0, 0, 0, 5, 6);
+assert.sameValue(d.toJSON(), "PT5H6M", "positive hours and minutes");
+d = new Temporal.Duration(0, 0, 0, 0, -5, -6);
+assert.sameValue(d.toJSON(), "-PT5H6M", "negative hours and minutes");
+d = new Temporal.Duration(0, 0, 3, 0, 0, 6);
+assert.sameValue(d.toJSON(), "P3WT6M", "positive weeks and minutes");
+d = new Temporal.Duration(0, 0, -3, 0, 0, -6);
+assert.sameValue(d.toJSON(), "-P3WT6M", "negative weeks and minutes");
+d = new Temporal.Duration(0, 0, 0, 4, 0, 6);
+assert.sameValue(d.toJSON(), "P4DT6M", "positive days and minutes");
+d = new Temporal.Duration(0, 0, 0, -4, 0, -6);
+assert.sameValue(d.toJSON(), "-P4DT6M", "negative days and minutes");
+
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 7);
+assert.sameValue(d.toJSON(), "PT7S", "positive seconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, -7);
+assert.sameValue(d.toJSON(), "-PT7S", "negative seconds");
+d = new Temporal.Duration(0, 0, 0, 0, 5, 0, 7);
+assert.sameValue(d.toJSON(), "PT5H7S", "positive hours and seconds");
+d = new Temporal.Duration(0, 0, 0, 0, -5, 0, -7);
+assert.sameValue(d.toJSON(), "-PT5H7S", "negative hours and seconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 6, 7);
+assert.sameValue(d.toJSON(), "PT6M7S", "positive minutes and seconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, -6, -7);
+assert.sameValue(d.toJSON(), "-PT6M7S", "negative minutes and seconds");
+d = new Temporal.Duration(0, 0, 0, 0, 5, 6, 7);
+assert.sameValue(d.toJSON(), "PT5H6M7S", "positive hours, minutes, seconds");
+d = new Temporal.Duration(0, 0, 0, 0, -5, -6, -7);
+assert.sameValue(d.toJSON(), "-PT5H6M7S", "negative hours, minutes, seconds");
+d = new Temporal.Duration(1, 0, 0, 0, 5, 6, 7);
+assert.sameValue(d.toJSON(), "P1YT5H6M7S", "positive years, hours, minutes, seconds");
+d = new Temporal.Duration(-1, 0, 0, 0, -5, -6, -7);
+assert.sameValue(d.toJSON(), "-P1YT5H6M7S", "negative years, hours, minutes, seconds");
+
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 8);
+assert.sameValue(d.toJSON(), "PT0.008S", "positive milliseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, -8);
+assert.sameValue(d.toJSON(), "-PT0.008S", "negative milliseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 80);
+assert.sameValue(d.toJSON(), "PT0.08S", "positive milliseconds multiple of 10");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, -80);
+assert.sameValue(d.toJSON(), "-PT0.08S", "negative milliseconds multiple of 10");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 87);
+assert.sameValue(d.toJSON(), "PT0.087S", "positive two-digit milliseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, -87);
+assert.sameValue(d.toJSON(), "-PT0.087S", "negative two-digit milliseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 876);
+assert.sameValue(d.toJSON(), "PT0.876S", "positive three-digit milliseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, -876);
+assert.sameValue(d.toJSON(), "-PT0.876S", "negative three-digit milliseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 876543);
+assert.sameValue(d.toJSON(), "PT876.543S", "positive large milliseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, -876543);
+assert.sameValue(d.toJSON(), "-PT876.543S", "negative large milliseconds");
+
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 9);
+assert.sameValue(d.toJSON(), "PT0.000009S", "positive microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -9);
+assert.sameValue(d.toJSON(), "-PT0.000009S", "negative microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 90);
+assert.sameValue(d.toJSON(), "PT0.00009S", "positive microseconds multiple of 10");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -90);
+assert.sameValue(d.toJSON(), "-PT0.00009S", "negative microseconds multiple of 10");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 98);
+assert.sameValue(d.toJSON(), "PT0.000098S", "positive two-digit microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -98);
+assert.sameValue(d.toJSON(), "-PT0.000098S", "negative two-digit microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 900);
+assert.sameValue(d.toJSON(), "PT0.0009S", "positive microseconds multiple of 100");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -900);
+assert.sameValue(d.toJSON(), "-PT0.0009S", "negative microseconds multiple of 100");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 987);
+assert.sameValue(d.toJSON(), "PT0.000987S", "positive three-digit microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -987);
+assert.sameValue(d.toJSON(), "-PT0.000987S", "negative three-digit microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 987654);
+assert.sameValue(d.toJSON(), "PT0.987654S", "positive large microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -987654);
+assert.sameValue(d.toJSON(), "-PT0.987654S", "negative large microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 987654321);
+assert.sameValue(d.toJSON(), "PT987.654321S", "positive larger microseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, -987654321);
+assert.sameValue(d.toJSON(), "-PT987.654321S", "negative larger microseconds");
+
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 1);
+assert.sameValue(d.toJSON(), "PT0.000000001S", "positive nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -1);
+assert.sameValue(d.toJSON(), "-PT0.000000001S", "negative nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 10);
+assert.sameValue(d.toJSON(), "PT0.00000001S", "positive nanoseconds multiple of 10");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -10);
+assert.sameValue(d.toJSON(), "-PT0.00000001S", "negative nanoseconds multiple of 10");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 12);
+assert.sameValue(d.toJSON(), "PT0.000000012S", "positive two-digit nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -12);
+assert.sameValue(d.toJSON(), "-PT0.000000012S", "negative two-digit nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 100);
+assert.sameValue(d.toJSON(), "PT0.0000001S", "positive nanoseconds multiple of 100");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -100);
+assert.sameValue(d.toJSON(), "-PT0.0000001S", "negative nanoseconds multiple of 100");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 123);
+assert.sameValue(d.toJSON(), "PT0.000000123S", "positive three-digit nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -123);
+assert.sameValue(d.toJSON(), "-PT0.000000123S", "negative three-digit nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 123456);
+assert.sameValue(d.toJSON(), "PT0.000123456S", "positive large nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -123456);
+assert.sameValue(d.toJSON(), "-PT0.000123456S", "negative large nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 123456789);
+assert.sameValue(d.toJSON(), "PT0.123456789S", "positive larger nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -123456789);
+assert.sameValue(d.toJSON(), "-PT0.123456789S", "negative larger nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, 1234567891);
+assert.sameValue(d.toJSON(), "PT1.234567891S", "positive even larger nanoseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 0, 0, 0, -1234567891);
+assert.sameValue(d.toJSON(), "-PT1.234567891S", "negative even larger nanoseconds");
+
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 4, 3, 2, 1);
+assert.sameValue(d.toJSON(), "PT4.003002001S", "positive seconds and subseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, -4, -3, -2, -1);
+assert.sameValue(d.toJSON(), "-PT4.003002001S", "negative seconds and subseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 4, 3, 2, 90001);
+assert.sameValue(d.toJSON(), "PT4.003092001S", "positive seconds and large subseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, -4, -3, -2, -90001);
+assert.sameValue(d.toJSON(), "-PT4.003092001S", "negative seconds and large subseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, 4, 3, 2, 90080001);
+assert.sameValue(d.toJSON(), "PT4.093082001S", "positive seconds and larger subseconds");
+d = new Temporal.Duration(0, 0, 0, 0, 0, 0, -4, -3, -2, -90080001);
+assert.sameValue(d.toJSON(), "-PT4.093082001S", "negative seconds and larger subseconds");
+
+d = new Temporal.Duration(1, 2, 3, 4, 5, 6, 7, 8, 9, 1);
+assert.sameValue(d.toJSON(), "P1Y2M3W4DT5H6M7.008009001S", "all fields positive");
+d = new Temporal.Duration(-1, -2, -3, -4, -5, -6, -7, -8, -9, -1);
+assert.sameValue(d.toJSON(), "-P1Y2M3W4DT5H6M7.008009001S", "all fields negative");
+
+d = new Temporal.Duration(1234, 2345, 3456, 4567, 5678, 6789, 7890, 890, 901, 123);
+assert.sameValue(d.toJSON(), "P1234Y2345M3456W4567DT5678H6789M7890.890901123S", "all fields large and positive");
+d = new Temporal.Duration(-1234, -2345, -3456, -4567, -5678, -6789, -7890, -890, -901, -123);
+assert.sameValue(d.toJSON(), "-P1234Y2345M3456W4567DT5678H6789M7890.890901123S", "all fields large and negative");