diff --git a/src/objects/intl-objects.cc b/src/objects/intl-objects.cc
index abeeb1d24c..d4251afa1f 100644
--- a/src/objects/intl-objects.cc
+++ b/src/objects/intl-objects.cc
@@ -537,7 +537,8 @@ std::set<std::string> Intl::BuildLocaleSet(
   return locales;
 }
 
-std::string Intl::DefaultLocale(Isolate* isolate) {
+namespace {
+std::string DefaultLocale(Isolate* isolate) {
   if (isolate->default_locale().empty()) {
     icu::Locale default_locale;
     // Translate ICU's fallback locale to a well-known locale.
@@ -557,6 +558,7 @@ std::string Intl::DefaultLocale(Isolate* isolate) {
   }
   return isolate->default_locale();
 }
+}  // namespace
 
 // See ecma402/#legacy-constructor.
 MaybeHandle<Object> Intl::LegacyUnwrapReceiver(Isolate* isolate,
@@ -876,7 +878,7 @@ MaybeHandle<String> Intl::StringLocaleConvertCase(Isolate* isolate,
     return MaybeHandle<String>();
   }
   std::string requested_locale = requested_locales.size() == 0
-                                     ? Intl::DefaultLocale(isolate)
+                                     ? DefaultLocale(isolate)
                                      : requested_locales[0];
   size_t dash = requested_locale.find('-');
   if (dash != std::string::npos) {
@@ -1548,7 +1550,7 @@ std::string LookupMatcher(Isolate* isolate,
   // 3. Let defLocale be DefaultLocale();
   // 4. Set result.[[locale]] to defLocale.
   // 5. Return result.
-  return Intl::DefaultLocale(isolate);
+  return DefaultLocale(isolate);
 }
 
 }  // namespace
diff --git a/src/objects/intl-objects.h b/src/objects/intl-objects.h
index 52ad215972..804f676eb5 100644
--- a/src/objects/intl-objects.h
+++ b/src/objects/intl-objects.h
@@ -62,8 +62,6 @@ class Intl {
       const std::set<std::string>& available_locales, Handle<Object> locales_in,
       Handle<Object> options_in);
 
-  static std::string DefaultLocale(Isolate* isolate);
-
   // ECMA402 9.2.10. GetOption( options, property, type, values, fallback)
   // ecma402/#sec-getoption
   //
diff --git a/src/runtime/runtime-intl.cc b/src/runtime/runtime-intl.cc
index 60ecd2f618..37cd2a45d7 100644
--- a/src/runtime/runtime-intl.cc
+++ b/src/runtime/runtime-intl.cc
@@ -52,14 +52,6 @@ RUNTIME_FUNCTION(Runtime_FormatListToParts) {
       isolate, JSListFormat::FormatListToParts(isolate, list_format, list));
 }
 
-RUNTIME_FUNCTION(Runtime_GetDefaultICULocale) {
-  HandleScope scope(isolate);
-
-  DCHECK_EQ(0, args.length());
-  return *isolate->factory()->NewStringFromAsciiChecked(
-      Intl::DefaultLocale(isolate).c_str());
-}
-
 RUNTIME_FUNCTION(Runtime_StringToLowerCaseIntl) {
   HandleScope scope(isolate);
   DCHECK_EQ(args.length(), 1);
diff --git a/src/runtime/runtime.h b/src/runtime/runtime.h
index 53987e181a..869de1c7bb 100644
--- a/src/runtime/runtime.h
+++ b/src/runtime/runtime.h
@@ -200,7 +200,6 @@ namespace internal {
 #define FOR_EACH_INTRINSIC_INTL(F, I) \
   F(FormatList, 2, 1)                 \
   F(FormatListToParts, 2, 1)          \
-  F(GetDefaultICULocale, 0, 1)        \
   F(StringToLowerCaseIntl, 1, 1)      \
   F(StringToUpperCaseIntl, 1, 1)  // End of macro.
 #else
diff --git a/test/intl/break-iterator/default-locale.js b/test/intl/break-iterator/default-locale.js
index e1a42a100a..fd379db1c8 100644
--- a/test/intl/break-iterator/default-locale.js
+++ b/test/intl/break-iterator/default-locale.js
@@ -37,9 +37,6 @@ assertFalse(options.locale === 'und');
 assertFalse(options.locale === '');
 assertFalse(options.locale === undefined);
 
-// Then check for legitimacy.
-assertLanguageTag(%GetDefaultICULocale(), options.locale);
-
 var iteratorNone = new Intl.v8BreakIterator();
 assertEquals(options.locale, iteratorNone.resolvedOptions().locale);
 
diff --git a/test/intl/break-iterator/wellformed-unsupported-locale.js b/test/intl/break-iterator/wellformed-unsupported-locale.js
deleted file mode 100644
index ffa44aef08..0000000000
--- a/test/intl/break-iterator/wellformed-unsupported-locale.js
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// Passing a well formed but unsupported locale falls back to default.
-
-var iterator = Intl.v8BreakIterator(['xx']);
-
-assertLanguageTag(%GetDefaultICULocale(), iterator.resolvedOptions().locale);
diff --git a/test/intl/collator/default-locale.js b/test/intl/collator/default-locale.js
index fd964f0620..56435d147f 100644
--- a/test/intl/collator/default-locale.js
+++ b/test/intl/collator/default-locale.js
@@ -37,9 +37,6 @@ assertFalse(options.locale === 'und');
 assertFalse(options.locale === '');
 assertFalse(options.locale === undefined);
 
-// Then check for legitimacy.
-assertLanguageTag(%GetDefaultICULocale(), options.locale);
-
 var collatorNone = new Intl.Collator();
 assertEquals(options.locale, collatorNone.resolvedOptions().locale);
 
@@ -49,5 +46,4 @@ assertEquals(options.locale, collatorBraket.resolvedOptions().locale);
 
 var collatorWithOptions = new Intl.Collator(undefined, {usage: 'search'});
 var locale = collatorWithOptions.resolvedOptions().locale;
-assertLanguageTag(%GetDefaultICULocale(), locale);
 assertEquals(locale.indexOf('-co-search'), -1);
diff --git a/test/intl/collator/options.js b/test/intl/collator/options.js
index f03ff2cafc..126bfc0959 100644
--- a/test/intl/collator/options.js
+++ b/test/intl/collator/options.js
@@ -5,14 +5,12 @@
 // No locale
 var collatorWithOptions = new Intl.Collator(undefined);
 var { locale, usage, collation } = collatorWithOptions.resolvedOptions();
-assertLanguageTag(%GetDefaultICULocale(), locale);
 assertEquals('sort', usage);
 assertEquals('default', collation);
 assertEquals(locale.indexOf('-co-search'), -1);
 
 collatorWithOptions = new Intl.Collator(undefined, {usage: 'sort'});
 var { locale, usage, collation } = collatorWithOptions.resolvedOptions();
-assertLanguageTag(%GetDefaultICULocale(), locale);
 assertEquals('sort', usage);
 assertEquals('default', collation);
 assertEquals(locale.indexOf('-co-search'), -1);
@@ -21,12 +19,10 @@ collatorWithOptions = new Intl.Collator(undefined, {usage: 'search'});
 var { locale, usage, collation } = collatorWithOptions.resolvedOptions();
 assertEquals('search', usage);
 assertEquals('default', collation);
-assertLanguageTag(%GetDefaultICULocale(), locale);
 assertEquals(locale.indexOf('-co-search'), -1);
 
 collatorWithOptions = new Intl.Collator(locale);
 var { locale, usage, collation } = collatorWithOptions.resolvedOptions();
-assertLanguageTag(%GetDefaultICULocale(), locale);
 assertEquals('sort', usage);
 assertEquals('default', collation);
 assertEquals(locale.indexOf('-co-search'), -1);
diff --git a/test/intl/collator/wellformed-unsupported-locale.js b/test/intl/collator/wellformed-unsupported-locale.js
deleted file mode 100644
index ad89e3e220..0000000000
--- a/test/intl/collator/wellformed-unsupported-locale.js
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// Passing a well formed but unsupported locale falls back to default.
-
-var collator = Intl.Collator(['xx']);
-
-assertLanguageTag(%GetDefaultICULocale(), collator.resolvedOptions().locale);
diff --git a/test/intl/date-format/default-locale.js b/test/intl/date-format/default-locale.js
index 2d79e895b5..ecc85da479 100644
--- a/test/intl/date-format/default-locale.js
+++ b/test/intl/date-format/default-locale.js
@@ -37,8 +37,5 @@ assertFalse(options.locale === 'und');
 assertFalse(options.locale === '');
 assertFalse(options.locale === undefined);
 
-// Then check for legitimacy.
-assertLanguageTag(%GetDefaultICULocale(), options.locale);
-
 var dtfNone = new Intl.DateTimeFormat();
 assertEquals(options.locale, dtfNone.resolvedOptions().locale);
diff --git a/test/intl/date-format/wellformed-unsupported-locale.js b/test/intl/date-format/wellformed-unsupported-locale.js
deleted file mode 100644
index b812164832..0000000000
--- a/test/intl/date-format/wellformed-unsupported-locale.js
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// Passing a well formed but unsupported locale falls back to default.
-
-var dtf = Intl.DateTimeFormat(['xx']);
-
-assertLanguageTag(%GetDefaultICULocale(), dtf.resolvedOptions().locale);
diff --git a/test/intl/default_locale.js b/test/intl/default_locale.js
new file mode 100644
index 0000000000..453f5e66ed
--- /dev/null
+++ b/test/intl/default_locale.js
@@ -0,0 +1,17 @@
+// Copyright 2018 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.
+
+// Environment Variables: LC_ALL=de
+
+assertEquals("de", (new Intl.Collator([])).resolvedOptions().locale);
+assertEquals("de", (new Intl.Collator(['xx'])).resolvedOptions().locale);
+assertEquals("de", (new Intl.Collator(undefined)).resolvedOptions().locale);
+assertEquals("de", (new Intl.Collator(undefined, {usage: 'sort'})).resolvedOptions().locale);
+assertEquals("de", (new Intl.Collator(undefined, {usage: 'search'})).resolvedOptions().locale);
+assertEquals("de", (new Intl.DateTimeFormat([])).resolvedOptions().locale);
+assertEquals("de", (new Intl.DateTimeFormat(['xx'])).resolvedOptions().locale);
+assertEquals("de", (new Intl.NumberFormat([])).resolvedOptions().locale);
+assertEquals("de", (new Intl.NumberFormat(['xx'])).resolvedOptions().locale);
+assertEquals("de", (new Intl.v8BreakIterator([])).resolvedOptions().locale);
+assertEquals("de", (new Intl.v8BreakIterator(['xx'])).resolvedOptions().locale);
diff --git a/test/intl/intl.status b/test/intl/intl.status
index 09c9b0603e..3841b287dc 100644
--- a/test/intl/intl.status
+++ b/test/intl/intl.status
@@ -42,14 +42,18 @@
   # noi18n cannot turn on ICU backend for Date
   'relative-time-format/default-locale-fr-CA': [SKIP],
   'relative-time-format/default-locale-pt-BR': [SKIP],
+
+  # Unable to change locale on Windows:
+  'default_locale': [SKIP],
 }],  # system == windows'
 
 ['system == android', {
   # Android's ICU data file does not have the Chinese/Japanese dictionary
   # required for the test to pass.
-  'break-iterator/zh-break': [FAIL],
+  'break-iterator/zh-break': [SKIP],
   # Unable to change locale on Android:
-  'relative-time-format/default-locale-fr-CA': [FAIL],
-  'relative-time-format/default-locale-pt-BR': [FAIL],
+  'relative-time-format/default-locale-fr-CA': [SKIP],
+  'relative-time-format/default-locale-pt-BR': [SKIP],
+  'default_locale': [SKIP],
 }],  # 'system == android'
 ]
diff --git a/test/intl/number-format/default-locale.js b/test/intl/number-format/default-locale.js
index a24aec2333..7e67176baf 100644
--- a/test/intl/number-format/default-locale.js
+++ b/test/intl/number-format/default-locale.js
@@ -37,8 +37,5 @@ assertFalse(options.locale === 'und');
 assertFalse(options.locale === '');
 assertFalse(options.locale === undefined);
 
-// Then check for legitimacy.
-assertLanguageTag(%GetDefaultICULocale(), options.locale);
-
 var nfNone = new Intl.NumberFormat();
 assertEquals(options.locale, nfNone.resolvedOptions().locale);
diff --git a/test/intl/number-format/wellformed-unsupported-locale.js b/test/intl/number-format/wellformed-unsupported-locale.js
deleted file mode 100644
index c51753928e..0000000000
--- a/test/intl/number-format/wellformed-unsupported-locale.js
+++ /dev/null
@@ -1,32 +0,0 @@
-// Copyright 2013 the V8 project authors. All rights reserved.
-// Redistribution and use in source and binary forms, with or without
-// modification, are permitted provided that the following conditions are
-// met:
-//
-//     * Redistributions of source code must retain the above copyright
-//       notice, this list of conditions and the following disclaimer.
-//     * Redistributions in binary form must reproduce the above
-//       copyright notice, this list of conditions and the following
-//       disclaimer in the documentation and/or other materials provided
-//       with the distribution.
-//     * Neither the name of Google Inc. nor the names of its
-//       contributors may be used to endorse or promote products derived
-//       from this software without specific prior written permission.
-//
-// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
-// "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
-// LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR
-// A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
-// OWNER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
-// SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
-// LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
-// DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
-// THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
-// (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
-// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
-
-// Passing a well formed but unsupported locale falls back to default.
-
-var nf = Intl.NumberFormat(['xx']);
-
-assertLanguageTag(%GetDefaultICULocale(), nf.resolvedOptions().locale);