diff --git a/test/intl/regress-10599.js b/test/intl/regress-10599.js
new file mode 100644
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+++ b/test/intl/regress-10599.js
@@ -0,0 +1,35 @@
+// Copyright 2020 the V8 project authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+// Test in sr-ME locale, we consistently use Latin for both month and
+// TimeZoneName.
+let someCyrillicRE = /\p{Script=Cyrillic}/u;
+let someLatinRE = /\p{Script=Latin}/u;
+let allLatinRE = /[\s\d\.\p{Script=Latin}]+/u;
+let allCyrillicRE = /^[\s\d\.\p{Script=Cyrillic}]+$/u;
+
+let d = new Date();
+let srMETimeZone = new Intl.DateTimeFormat("sr-ME",
+    {timeZoneName: "long", timeZone: "America/Los_Angeles"});
+let srMEMonth = new Intl.DateTimeFormat("sr-ME", {month: "long"});
+let srTimeZone = new Intl.DateTimeFormat("sr",
+    {timeZoneName: "long", timeZone: "America/Los_Angeles"});
+let srMonth = new Intl.DateTimeFormat("sr", {month: "long"});
+
+let srMETimeZoneString = srMETimeZone.format(d);
+let srMEMonthString = srMEMonth.format(d);
+let srTimeZoneString = srTimeZone.format(d);
+let srMonthString = srMonth.format(d);
+
+// sr-ME should have both in Latin
+assertTrue(allLatinRE.test(srMETimeZoneString), srMETimeZoneString);
+assertTrue(allLatinRE.test(srMEMonthString), srMEMonthString);
+assertFalse(someCyrillicRE.test(srMETimeZoneString), srMETimeZoneString);
+assertFalse(someCyrillicRE.test(srMEMonthString), srMEMonthString);
+
+// sr should have both in Cyrillic
+assertTrue(allCyrillicRE.test(srTimeZoneString), srTimeZoneString);
+assertTrue(allCyrillicRE.test(srMonthString), srMonthString);
+assertFalse(someLatinRE.test(srTimeZoneString), srTimeZoneString);
+assertFalse(someLatinRE.test(srMonthString), srMonthString);