diff --git a/devtools/server/actors/errordocs.js b/devtools/server/actors/errordocs.js
index 17b05b7daa6d..60b02a9eaab5 100644
--- a/devtools/server/actors/errordocs.js
+++ b/devtools/server/actors/errordocs.js
@@ -73,7 +73,6 @@ const ErrorDocs = {
   JSMSG_GETTER_ONLY: "Getter_only",
   JSMSG_INVALID_DATE: "Invalid_date",
   JSMSG_DEPRECATED_STRING_METHOD: "Deprecated_String_generics",
-  JSMSG_DEPRECATED_TOLOCALEFORMAT: "Deprecated_toLocaleFormat",
   JSMSG_RESERVED_ID: "Reserved_identifier",
   JSMSG_BAD_CONST_ASSIGN: "Invalid_const_assignment",
   JSMSG_BAD_CONST_DECL: "Missing_initializer_in_const",
diff --git a/js/src/jit-test/tests/basic/testCrossCompartmentTransparency.js b/js/src/jit-test/tests/basic/testCrossCompartmentTransparency.js
index f4b363ec6885..e6ca7e87fbcd 100644
--- a/js/src/jit-test/tests/basic/testCrossCompartmentTransparency.js
+++ b/js/src/jit-test/tests/basic/testCrossCompartmentTransparency.js
@@ -148,7 +148,6 @@ test("new Date()", d => justDontThrow(Date.prototype.toISOString.call(d)));
 test("new Date()", d => justDontThrow(Date.prototype.toLocaleString.call(d)));
 test("new Date()", d => justDontThrow(Date.prototype.toLocaleDateString.call(d)));
 test("new Date()", d => justDontThrow(Date.prototype.toLocaleTimeString.call(d)));
-test("new Date()", d => justDontThrow(Date.prototype.toLocaleFormat.call(d)));
 test("new Date()", d => justDontThrow(Date.prototype.toTimeString.call(d)));
 test("new Date()", d => justDontThrow(Date.prototype.toDateString.call(d)));
 test("new Date()", d => justDontThrow(Date.prototype.toSource.call(d)));
diff --git a/js/src/js.msg b/js/src/js.msg
index 1dbabbfda3b3..d2419acf4ae2 100644
--- a/js/src/js.msg
+++ b/js/src/js.msg
@@ -124,7 +124,6 @@ MSG_DEF(JSMSG_CANT_DECLARE_GLOBAL_BINDING, 2, JSEXN_TYPEERR, "cannot declare glo
 // Date
 MSG_DEF(JSMSG_INVALID_DATE,            0, JSEXN_RANGEERR, "invalid date")
 MSG_DEF(JSMSG_BAD_TOISOSTRING_PROP,    0, JSEXN_TYPEERR, "toISOString property is not callable")
-MSG_DEF(JSMSG_DEPRECATED_TOLOCALEFORMAT, 0, JSEXN_WARN, "Date.prototype.toLocaleFormat is deprecated; consider using Intl.DateTimeFormat instead")
 
 // String
 MSG_DEF(JSMSG_BAD_URI,                 0, JSEXN_URIERR, "malformed URI sequence")
diff --git a/js/src/jscompartment.cpp b/js/src/jscompartment.cpp
index 8e258e1142ca..551f52ca3584 100644
--- a/js/src/jscompartment.cpp
+++ b/js/src/jscompartment.cpp
@@ -55,7 +55,6 @@ JSCompartment::JSCompartment(Zone* zone, const JS::CompartmentOptions& options =
     isAtomsCompartment_(false),
     isSelfHosting(false),
     marked(true),
-    warnedAboutDateToLocaleFormat(false),
     warnedAboutExprClosure(false),
     warnedAboutForEach(false),
     warnedAboutLegacyGenerator(false),
diff --git a/js/src/jscompartment.h b/js/src/jscompartment.h
index 45fef600252a..f62a1f7fdb09 100644
--- a/js/src/jscompartment.h
+++ b/js/src/jscompartment.h
@@ -622,7 +622,6 @@ struct JSCompartment
   public:
     bool                         isSelfHosting;
     bool                         marked;
-    bool                         warnedAboutDateToLocaleFormat : 1;
     bool                         warnedAboutExprClosure : 1;
     bool                         warnedAboutForEach : 1;
     bool                         warnedAboutLegacyGenerator : 1;
diff --git a/js/src/jsdate.cpp b/js/src/jsdate.cpp
index 93590c70018d..01bd1c42a6cb 100644
--- a/js/src/jsdate.cpp
+++ b/js/src/jsdate.cpp
@@ -2733,6 +2733,7 @@ FormatDate(JSContext* cx, double utcTime, FormatSpec format, MutableHandleValue
     return true;
 }
 
+#if !EXPOSE_INTL_API
 static bool
 ToLocaleFormatHelper(JSContext* cx, HandleObject obj, const char* format, MutableHandleValue rval)
 {
@@ -2778,7 +2779,7 @@ ToLocaleFormatHelper(JSContext* cx, HandleObject obj, const char* format, Mutabl
     return true;
 }
 
-#if !EXPOSE_INTL_API
+
 /* ES5 15.9.5.5. */
 MOZ_ALWAYS_INLINE bool
 date_toLocaleString_impl(JSContext* cx, const CallArgs& args)
@@ -2849,56 +2850,6 @@ date_toLocaleTimeString(JSContext* cx, unsigned argc, Value* vp)
 }
 #endif /* !EXPOSE_INTL_API */
 
-MOZ_ALWAYS_INLINE bool
-date_toLocaleFormat_impl(JSContext* cx, const CallArgs& args)
-{
-    Rooted<DateObject*> dateObj(cx, &args.thisv().toObject().as<DateObject>());
-
-#if EXPOSE_INTL_API
-    if (!cx->compartment()->warnedAboutDateToLocaleFormat) {
-        if (!JS_ReportErrorFlagsAndNumberASCII(cx, JSREPORT_WARNING, GetErrorMessage, nullptr,
-                                               JSMSG_DEPRECATED_TOLOCALEFORMAT))
-        {
-            return false;
-        }
-        cx->compartment()->warnedAboutDateToLocaleFormat = true;
-    }
-#endif
-
-    if (args.length() == 0) {
-        /*
-         * Use '%#c' for windows, because '%c' is backward-compatible and non-y2k
-         * with msvc; '%#c' requests that a full year be used in the result string.
-         */
-        static const char format[] =
-#if defined(_WIN32) && !defined(__MWERKS__)
-                                       "%#c"
-#else
-                                       "%c"
-#endif
-                                       ;
-
-        return ToLocaleFormatHelper(cx, dateObj, format, args.rval());
-    }
-
-    RootedString fmt(cx, ToString<CanGC>(cx, args[0]));
-    if (!fmt)
-        return false;
-
-    JSAutoByteString fmtbytes(cx, fmt);
-    if (!fmtbytes)
-        return false;
-
-    return ToLocaleFormatHelper(cx, dateObj, fmtbytes.ptr(), args.rval());
-}
-
-static bool
-date_toLocaleFormat(JSContext* cx, unsigned argc, Value* vp)
-{
-    CallArgs args = CallArgsFromVp(argc, vp);
-    return CallNonGenericMethod<IsDate, date_toLocaleFormat_impl>(cx, args);
-}
-
 /* ES5 15.9.5.4. */
 MOZ_ALWAYS_INLINE bool
 date_toTimeString_impl(JSContext* cx, const CallArgs& args)
@@ -3055,7 +3006,6 @@ static const JSFunctionSpec date_methods[] = {
     JS_FN("setMilliseconds",     date_setMilliseconds,    1,0),
     JS_FN("setUTCMilliseconds",  date_setUTCMilliseconds, 1,0),
     JS_FN("toUTCString",         date_toGMTString,        0,0),
-    JS_FN("toLocaleFormat",      date_toLocaleFormat,     0,0),
 #if EXPOSE_INTL_API
     JS_SELF_HOSTED_FN(js_toLocaleString_str, "Date_toLocaleString", 0,0),
     JS_SELF_HOSTED_FN("toLocaleDateString", "Date_toLocaleDateString", 0,0),
diff --git a/js/src/tests/ecma_5/extensions/extension-methods-reject-null-undefined-this.js b/js/src/tests/ecma_5/extensions/extension-methods-reject-null-undefined-this.js
index 5ea399fe8719..d0364a26ad09 100644
--- a/js/src/tests/ecma_5/extensions/extension-methods-reject-null-undefined-this.js
+++ b/js/src/tests/ecma_5/extensions/extension-methods-reject-null-undefined-this.js
@@ -34,8 +34,7 @@ var ClassToMethodMap =
                "sup", "sub", "substr", "trimLeft", "trimRight", "toJSON"],
     Boolean:  ["toSource", "toJSON"],
     Number:   ["toSource", "toJSON"],
-    Date:     ["toSource", "toLocaleFormat", "getYear", "setYear",
-               "toGMTString"],
+    Date:     ["toSource", "getYear", "setYear",  "toGMTString"],
     RegExp:   ["toSource"],
     Error:    ["toSource"],
   };
diff --git a/js/src/tests/js1_5/extensions/toLocaleFormat-01.js b/js/src/tests/js1_5/extensions/toLocaleFormat-01.js
deleted file mode 100644
index 02f269125dd6..000000000000
--- a/js/src/tests/js1_5/extensions/toLocaleFormat-01.js
+++ /dev/null
@@ -1,230 +0,0 @@
-/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*- */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-//-----------------------------------------------------------------------------
-var BUGNUMBER = 291494;
-var summary = 'Date.prototype.toLocaleFormat extension';
-var actual = '';
-var expect = '';
-var temp;
-
-/*
- * SpiderMonkey only.
- *
- * When the output of toLocaleFormat exceeds 100 bytes toLocaleFormat
- * defaults to using toString to produce the result.
-*/
-
-enterFunc ('test');
-printBugNumber(BUGNUMBER);
-printStatus (summary);
-
-var date = new Date("06/05/2005 00:00:00 GMT-0000");
-
-expect = date.getTimezoneOffset() > 0 ? 'Sat' : 'Sun';
-actual = date.toLocaleFormat('%a');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%a")');
-
-expect = date.getTimezoneOffset() > 0 ? 'Saturday' : 'Sunday';
-actual = date.toLocaleFormat('%A');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%A")');
-
-expect = 'Jun';
-actual = date.toLocaleFormat('%b');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%b")');
-
-expect = 'June';
-actual = date.toLocaleFormat('%B');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%B")');
-
-expect = (date.getTimezoneOffset() > 0) ? '04' : '05';
-actual = date.toLocaleFormat('%d');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%d")');
-
-expect = '0';
-actual = String((Number(date.toLocaleFormat('%H')) +
-                 date.getTimezoneOffset()/60) % 24);
-reportCompare(expect, actual, 'Date.toLocaleFormat(%H)');
-
-expect = '12';
-actual = String(Number(date.toLocaleFormat('%I')) +
-                date.getTimezoneOffset()/60);
-reportCompare(expect, actual, 'Date.toLocaleFormat(%I)');
-
-expect = String(155 + ((date.getTimezoneOffset() > 0) ? 0 : 1));
-actual = date.toLocaleFormat('%j');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%j")');
-
-expect = '06';
-actual = date.toLocaleFormat('%m');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%m")');
-
-expect = '00';
-actual = date.toLocaleFormat('%M');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%M")');
-
-expect = true;
-temp   = date.toLocaleFormat('%p');
-actual = temp == 'AM' || date.toLocaleFormat('%p') == 'PM';
-reportCompare(expect, actual, 'Date.toLocaleFormat("%p") is AM or PM');
-
-expect = '00';
-actual = date.toLocaleFormat('%S');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%S")');
-
-expect = String(22 + ((date.getTimezoneOffset() > 0) ? 0 : 1));
-actual = date.toLocaleFormat('%U');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%U")');
-
-expect = String((6 + ((date.getTimezoneOffset() > 0) ? 0 : 1))%7);
-actual = date.toLocaleFormat('%w');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%w")');
-
-expect = '22';
-actual = date.toLocaleFormat('%W');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%W")');
-
-expect = '05';
-actual = date.toLocaleFormat('%y');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%y")');
-
-expect = '2005';
-actual = date.toLocaleFormat('%Y');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%Y")');
-
-expect = '%';
-actual = date.toLocaleFormat('%%');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%%")');
-
-
-expect = '1899 99';
-temp='%Y %y';
-actual = new Date(0, 0, 0, 13, 14, 15, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '1899189918991899189918991899189918991899189918991899189918991899189918991899189918991899';
-temp = '%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(0, 0, 0, 13, 14, 15, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = 'xxx189918991899189918991899189918991899189918991899189918991899189918991899189918991899189918991899';
-temp = 'xxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(0, 0, 0, 13, 14, 15, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = new Date(0, 0, 0, 13, 14, 15, 0).toString();
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(0, 0, 0, 13, 14, 15, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = 'xxxx189918991899189918991899189918991899';
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(0, 0, 0, 13, 14, 15, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-
-expect = '-51 49';
-temp = '%Y %y';
-actual = new Date(-51, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51';
-temp = '%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(-51, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = 'xxx-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51-51';
-temp = 'xxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(-51, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = new Date(-51, 0).toString();
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(-51, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-
-expect = '1851 51';
-temp = '%Y %y';
-actual = new Date(1851, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '1851185118511851185118511851185118511851185118511851185118511851185118511851185118511851';
-temp = '%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(1851, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = 'xxx185118511851185118511851185118511851185118511851185118511851185118511851185118511851185118511851';
-temp = 'xxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(1851, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = new Date(1851, 0).toString();
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(1851, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-
-expect = '-1 99';
-temp = '%Y %y';
-actual = new Date(-1, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '-100 00';
-temp = '%Y %y';
-actual = new Date(-100, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '1900 00';
-temp = '%Y %y';
-actual = new Date(0, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '1901 01';
-temp = '%Y %y';
-actual = new Date(1, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '1970 70';
-temp = '%Y %y';
-actual = new Date(1970, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-
-expect = new Date(32767, 0).toString();
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(32767, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = '32767327673276732767327673276732767327673276732767327673276732767327673276732767327673276732767';
-temp = '%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(32767, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = 'xxxx32767327673276732767327673276732767327673276732767327673276732767327673276732767327673276732767';
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(32767, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = new Date(32767, 0).toString();
-temp = 'xxxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(32767, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-
-expect = '-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999';
-temp = '%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(-9999, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = 'xxxx-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999-9999';
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(-9999, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
-
-expect = new Date(-9999, 0).toString();
-temp = 'xxxx%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y%Y';
-actual = new Date(-9999, 0).toLocaleFormat(temp);
-reportCompare(expect, actual, 'Date.toLocaleFormat("'+temp+'")');
diff --git a/js/src/tests/js1_5/extensions/toLocaleFormat-02.js b/js/src/tests/js1_5/extensions/toLocaleFormat-02.js
deleted file mode 100644
index efb4e8221426..000000000000
--- a/js/src/tests/js1_5/extensions/toLocaleFormat-02.js
+++ /dev/null
@@ -1,105 +0,0 @@
-// |reftest| skip-if(xulRuntime.OS=="WINNT")
-/* -*- Mode: C++; tab-width: 2; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-//-----------------------------------------------------------------------------
-var BUGNUMBER = 291494;
-var summary = 'Date.prototype.toLocaleFormat extension';
-var actual = '';
-var expect = '';
-var temp;
-
-/*
- * SpiderMonkey only.
- *
- * This test uses format strings which are not supported cross
- * platform and are expected to fail on at least some platforms
- * however they all currently pass on Linux (Fedora Core 6). They are
- * included here in order to increase coverage for cases where a crash
- * may occur.  These failures will be tracked in the
- * mozilla/js/tests/public-failures.txt list.
- * 
- */
-
-enterFunc ('test');
-printBugNumber(BUGNUMBER);
-printStatus (summary);
- 
-var date = new Date("06/05/2005 00:00:00 GMT-0000");
-
-expect = '20';
-actual = date.toLocaleFormat('%C');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%C")');
-
-expect = date.toLocaleFormat('%C%y');
-actual = date.toLocaleFormat('%Y');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%C%y") == ' +
-              'Date.toLocaleFormat("%Y")');
-
-expect = date.toLocaleFormat('%m/%d/%y');
-actual = date.toLocaleFormat('%D');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%m/%d/%y") == ' +
-              'Date.toLocaleFormat("%D")');
-
-expect = (date.getTimezoneOffset() > 0) ? ' 4' : ' 5';
-actual = date.toLocaleFormat('%e');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%e")');
-
-expect = date.toLocaleFormat('%Y-%m-%d');
-actual = date.toLocaleFormat('%F');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%Y-%m-%d") == ' +
-              'Date.toLocaleFormat("%F")');
-
-expect = '05';
-actual = date.toLocaleFormat('%g');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%g")');
-
-expect = '2005';
-actual = date.toLocaleFormat('%G');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%G")');
-
-expect = date.toLocaleFormat('%b');
-actual = date.toLocaleFormat('%h');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%b") == ' +
-              'Date.toLocaleFormat("%h")');
-
-expect = '\n';
-actual = date.toLocaleFormat('%n');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%n") == "\\n"');
-
-expect = date.toLocaleFormat('%I:%M:%S %p');
-actual = date.toLocaleFormat('%r');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%I:%M:%S %p") == ' +
-              'Date.toLocaleFormat("%r")');
-
-expect = date.toLocaleFormat('%H:%M');
-actual = date.toLocaleFormat('%R');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%H:%M") == ' +
-              'Date.toLocaleFormat("%R")');
-
-expect = '\t';
-actual = date.toLocaleFormat('%t');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%t") == "\\t"');
-
-expect = date.toLocaleFormat('%H:%M:%S');
-actual = date.toLocaleFormat('%T');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%H:%M:%S") == ' +
-              'Date.toLocaleFormat("%T")');
-
-expect = String(6 + ((date.getTimezoneOffset() > 0) ? 0 : 1));
-actual = date.toLocaleFormat('%u');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%u")');
-
-expect = '22';
-actual = date.toLocaleFormat('%V');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%V")');
-
-print('Note: For Date.toLocaleFormat("%m/%d/%y") == Date.toLocaleFormat("%x") ' + 
-      'to pass in Windows, the Regional Setting for the short date must be ' + 
-      'set to mm/dd/yyyy');
-expect = date.toLocaleFormat('%m/%d/%Y');
-actual = date.toLocaleFormat('%x');
-reportCompare(expect, actual, 'Date.toLocaleFormat("%m/%d/%Y") == ' +
-              'Date.toLocaleFormat("%x")');
diff --git a/js/src/tests/js1_5/extensions/toLocaleFormat-deprecated-no-Intl.js b/js/src/tests/js1_5/extensions/toLocaleFormat-deprecated-no-Intl.js
deleted file mode 100644
index e1ffd646acb8..000000000000
--- a/js/src/tests/js1_5/extensions/toLocaleFormat-deprecated-no-Intl.js
+++ /dev/null
@@ -1,18 +0,0 @@
-// |reftest| skip-if(!xulRuntime.shell||this.hasOwnProperty("Intl"))
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-// Don't warn about Date.prototype.toLocaleFormat() when Intl isn't supported.
-
-enableLastWarning();
-
-new Date().toLocaleFormat("%Y");
-
-var warning = getLastWarning();
-assertEq(warning, null, "warning shouldn't be emitted for toLocaleFormat");
-
-disableLastWarning();
-
-if (typeof reportCompare === 'function')
-    reportCompare(0, 0);
diff --git a/js/src/tests/js1_5/extensions/toLocaleFormat-deprecated.js b/js/src/tests/js1_5/extensions/toLocaleFormat-deprecated.js
deleted file mode 100644
index 618aa6c877b7..000000000000
--- a/js/src/tests/js1_5/extensions/toLocaleFormat-deprecated.js
+++ /dev/null
@@ -1,28 +0,0 @@
-// |reftest| skip-if(!xulRuntime.shell||!this.hasOwnProperty("Intl"))
-/* This Source Code Form is subject to the terms of the Mozilla Public
- * License, v. 2.0. If a copy of the MPL was not distributed with this
- * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
-
-// Warn once about Date.prototype.toLocaleFormat().
-
-enableLastWarning();
-
-new Date().toLocaleFormat("%Y");
-
-var warning = getLastWarning();
-assertEq(warning !== null, true, "warning should be emitted for toLocaleFormat");
-assertEq(warning.name, "Warning");
-assertEq(warning.message.indexOf("toLocaleFormat") !== -1, true,
-         "warning should mention toLocaleFormat");
-
-clearLastWarning();
-
-new Date().toLocaleFormat("%Y");
-
-warning = getLastWarning();
-assertEq(warning, null, "warning shouldn't be emitted for 2nd call to toLocaleFormat");
-
-disableLastWarning();
-
-if (typeof reportCompare === 'function')
-    reportCompare(0, 0);
diff --git a/js/src/vm/Time.cpp b/js/src/vm/Time.cpp
index 9ad56f30a7d6..4578df197626 100644
--- a/js/src/vm/Time.cpp
+++ b/js/src/vm/Time.cpp
@@ -322,8 +322,6 @@ PRMJ_FormatTime(char* buf, int buflen, const char* fmt, PRMJTime* prtm)
      * Note that FAKE_YEAR_BASE should be a multiple of 100 to make 2-digit
      * year formats (%y) work correctly (since we won't find the fake year
      * in that case).
-     * e.g. new Date(1873, 0).toLocaleFormat('%Y %y') => "1873 73"
-     * See bug 327869.
      */
 #define FAKE_YEAR_BASE 9900
     if (prtm->tm_year < 1900 || prtm->tm_year > 9999) {
diff --git a/js/xpconnect/src/XPCLocale.cpp b/js/xpconnect/src/XPCLocale.cpp
index ce92cdea2ab9..cd6f2ded7c59 100644
--- a/js/xpconnect/src/XPCLocale.cpp
+++ b/js/xpconnect/src/XPCLocale.cpp
@@ -8,11 +8,8 @@
 
 #include "jsapi.h"
 
-#include "nsCollationCID.h"
 #include "nsJSUtils.h"
-#include "nsICollation.h"
 #include "nsIObserver.h"
-#include "nsNativeCharsetUtils.h"
 #include "nsComponentManagerUtils.h"
 #include "nsServiceManagerUtils.h"
 #include "mozilla/CycleCollectedJSContext.h"
@@ -76,11 +73,12 @@ struct XPCLocaleCallbacks : public JSLocaleCallbacks
 
     // Disable the toLocaleUpper/Lower case hooks to use the standard,
     // locale-insensitive definition from String.prototype. (These hooks are
-    // only consulted when EXPOSE_INTL_API is not set.)
+    // only consulted when EXPOSE_INTL_API is not set.) Since EXPOSE_INTL_API
+    // is always set, these hooks should be disabled.
     localeToUpperCase = nullptr;
     localeToLowerCase = nullptr;
-    localeCompare = LocaleCompare;
-    localeToUnicode = LocaleToUnicode;
+    localeCompare = nullptr;
+    localeToUnicode = nullptr;
 
     // It's going to be retained by the ObserverService.
     RefPtr<XPCLocaleObserver> locObs = new XPCLocaleObserver();
@@ -93,15 +91,6 @@ struct XPCLocaleCallbacks : public JSLocaleCallbacks
     MOZ_COUNT_DTOR(XPCLocaleCallbacks);
   }
 
-  /**
-   * Return the XPCLocaleCallbacks from |cx|'s runtime (see below).
-   */
-  static XPCLocaleCallbacks*
-  This(JSContext* cx)
-  {
-    return This(JS_GetRuntime(cx));
-  }
-
   /**
    * Return the XPCLocaleCallbacks that's hidden away in |rt|. (This impl uses
    * the locale callbacks struct to store away its per-context data.)
@@ -115,93 +104,20 @@ struct XPCLocaleCallbacks : public JSLocaleCallbacks
     MOZ_ASSERT(lc);
     MOZ_ASSERT(lc->localeToUpperCase == nullptr);
     MOZ_ASSERT(lc->localeToLowerCase == nullptr);
-    MOZ_ASSERT(lc->localeCompare == LocaleCompare);
-    MOZ_ASSERT(lc->localeToUnicode == LocaleToUnicode);
+    MOZ_ASSERT(lc->localeCompare == nullptr);
+    MOZ_ASSERT(lc->localeToUnicode == nullptr);
 
     const XPCLocaleCallbacks* ths = static_cast<const XPCLocaleCallbacks*>(lc);
     ths->AssertThreadSafety();
     return const_cast<XPCLocaleCallbacks*>(ths);
   }
 
-  static bool
-  LocaleToUnicode(JSContext* cx, const char* src, MutableHandleValue rval)
-  {
-    return This(cx)->ToUnicode(cx, src, rval);
-  }
-
-  static bool
-  LocaleCompare(JSContext* cx, HandleString src1, HandleString src2, MutableHandleValue rval)
-  {
-    return This(cx)->Compare(cx, src1, src2, rval);
-  }
-
 private:
-  bool
-  Compare(JSContext* cx, HandleString src1, HandleString src2, MutableHandleValue rval)
-  {
-    nsresult rv;
-
-    if (!mCollation) {
-      nsCOMPtr<nsICollationFactory> colFactory =
-        do_CreateInstance(NS_COLLATIONFACTORY_CONTRACTID, &rv);
-
-      if (NS_SUCCEEDED(rv)) {
-        rv = colFactory->CreateCollation(getter_AddRefs(mCollation));
-      }
-
-      if (NS_FAILED(rv)) {
-        xpc::Throw(cx, rv);
-        return false;
-      }
-    }
-
-    nsAutoJSString autoStr1, autoStr2;
-    if (!autoStr1.init(cx, src1) || !autoStr2.init(cx, src2)) {
-      return false;
-    }
-
-    int32_t result;
-    rv = mCollation->CompareString(nsICollation::kCollationStrengthDefault,
-                                   autoStr1, autoStr2, &result);
-
-    if (NS_FAILED(rv)) {
-      xpc::Throw(cx, rv);
-      return false;
-    }
-
-    rval.setInt32(result);
-    return true;
-  }
-
-  bool
-  ToUnicode(JSContext* cx, const char* src, MutableHandleValue rval)
-  {
-    // This code is only used by our prioprietary toLocaleFormat method
-    // and should be removed once we get rid of it.
-    // toLocaleFormat is used in non-ICU scenarios where we don't have
-    // access to any other date/time than the OS one, so we have to also
-    // use the OS locale for unicode conversions.
-    // See bug 1349470 for more details.
-    nsAutoString result;
-    NS_CopyNativeToUnicode(nsDependentCString(src), result);
-    JSString* ucstr =
-      JS_NewUCStringCopyN(cx, result.get(), result.Length());
-    if (ucstr) {
-      rval.setString(ucstr);
-      return true;
-    }
-
-    xpc::Throw(cx, NS_ERROR_OUT_OF_MEMORY);
-    return false;
-  }
-
   void AssertThreadSafety() const
   {
     NS_ASSERT_OWNINGTHREAD(XPCLocaleCallbacks);
   }
 
-  nsCOMPtr<nsICollation> mCollation;
-
   NS_DECL_OWNINGTHREAD
 };
 
diff --git a/js/xpconnect/tests/chrome/test_xrayToJS.xul b/js/xpconnect/tests/chrome/test_xrayToJS.xul
index 2100dea72d6c..74fd8fae0a60 100644
--- a/js/xpconnect/tests/chrome/test_xrayToJS.xul
+++ b/js/xpconnect/tests/chrome/test_xrayToJS.xul
@@ -182,7 +182,7 @@ https://bugzilla.mozilla.org/show_bug.cgi?id=933681
     "setYear", "setFullYear", "setUTCFullYear", "setMonth", "setUTCMonth",
     "setDate", "setUTCDate", "setHours", "setUTCHours", "setMinutes",
     "setUTCMinutes", "setSeconds", "setUTCSeconds", "setMilliseconds",
-    "setUTCMilliseconds", "toUTCString", "toLocaleFormat", "toLocaleString",
+    "setUTCMilliseconds", "toUTCString", "toLocaleString",
     "toLocaleDateString", "toLocaleTimeString", "toDateString", "toTimeString",
     "toISOString", "toJSON", "toSource", "toString", "valueOf", "constructor",
     "toGMTString", Symbol.toPrimitive];
diff --git a/toolkit/xre/nsAppRunner.cpp b/toolkit/xre/nsAppRunner.cpp
index 3fc052559b58..74b4c17a7944 100644
--- a/toolkit/xre/nsAppRunner.cpp
+++ b/toolkit/xre/nsAppRunner.cpp
@@ -5223,6 +5223,7 @@ SetupErrorHandling(const char* progname)
   setbuf(stdout, 0);
 }
 
+// Note: This function should not be needed anymore. See Bug 818634 for details.
 void
 OverrideDefaultLocaleIfNeeded() {
   // Read pref to decide whether to override default locale with US English.