diff --git a/src/Symfony/Component/Intl/Locales.php b/src/Symfony/Component/Intl/Locales.php
index c5def031cf47..1f434ee2672c 100644
--- a/src/Symfony/Component/Intl/Locales.php
+++ b/src/Symfony/Component/Intl/Locales.php
@@ -44,7 +44,7 @@ public static function exists(string $locale): bool
 
             return true;
         } catch (MissingResourceException $e) {
-            return false;
+            return \in_array($locale, self::getAliases(), true);
         }
     }
 
@@ -53,7 +53,15 @@ public static function exists(string $locale): bool
      */
     public static function getName(string $locale, string $displayLocale = null): string
     {
-        return self::readEntry(['Names', $locale], $displayLocale);
+        try {
+            return self::readEntry(['Names', $locale], $displayLocale);
+        } catch (MissingResourceException $e) {
+            if (false === $aliased = array_search($locale, self::getAliases(), true)) {
+                throw $e;
+            }
+
+            return self::readEntry(['Names', $aliased], $displayLocale);
+        }
     }
 
     /**
diff --git a/src/Symfony/Component/Intl/Tests/LocalesTest.php b/src/Symfony/Component/Intl/Tests/LocalesTest.php
index ae419eaa67e5..5ccff4923f4e 100644
--- a/src/Symfony/Component/Intl/Tests/LocalesTest.php
+++ b/src/Symfony/Component/Intl/Tests/LocalesTest.php
@@ -92,9 +92,16 @@ public function testGetNameWithInvalidLocale()
         Locales::getName('foo');
     }
 
+    public function testGetNameWithAliasLocale()
+    {
+        $this->assertSame(Locales::getName('tl_PH'), Locales::getName('fil_PH'));
+    }
+
     public function testExists()
     {
         $this->assertTrue(Locales::exists('nl_NL'));
+        $this->assertTrue(Locales::exists('tl_PH'));
+        $this->assertTrue(Locales::exists('fil_PH')); // alias for "tl_PH"
         $this->assertFalse(Locales::exists('zxx_ZZ'));
     }
 }
diff --git a/src/Symfony/Component/Intl/Tests/TimezonesTest.php b/src/Symfony/Component/Intl/Tests/TimezonesTest.php
index 58a9a3600190..cc000c148270 100644
--- a/src/Symfony/Component/Intl/Tests/TimezonesTest.php
+++ b/src/Symfony/Component/Intl/Tests/TimezonesTest.php
@@ -530,14 +530,23 @@ public function testGetNameDefaultLocale()
     /**
      * @expectedException \Symfony\Component\Intl\Exception\MissingResourceException
      */
-    public function testGetNameWithInvalidTimezoneId()
+    public function testGetNameWithInvalidTimezone()
     {
         Timezones::getName('foo');
     }
 
+    /**
+     * @expectedException \Symfony\Component\Intl\Exception\MissingResourceException
+     */
+    public function testGetNameWithAliasTimezone()
+    {
+        Timezones::getName('US/Pacific'); // alias in icu (not compiled), name unavailable in php
+    }
+
     public function testExists()
     {
         $this->assertTrue(Timezones::exists('Europe/Amsterdam'));
+        $this->assertTrue(Timezones::exists('US/Pacific')); // alias in icu (not compiled), identifier available in php
         $this->assertFalse(Timezones::exists('Etc/Unknown'));
     }
 
@@ -547,6 +556,9 @@ public function testGetRawOffset()
         $this->assertSame(0, Timezones::getRawOffset('Etc/UTC'));
         $this->assertSame(-10800, Timezones::getRawOffset('America/Buenos_Aires'));
         $this->assertSame(20700, Timezones::getRawOffset('Asia/Katmandu'));
+
+        // ensure we support identifiers available in php (not compiled from icu)
+        Timezones::getRawOffset('US/Pacific');
     }
 
     /**
diff --git a/src/Symfony/Component/Intl/Timezones.php b/src/Symfony/Component/Intl/Timezones.php
index 08f81b830548..1058a0978be5 100644
--- a/src/Symfony/Component/Intl/Timezones.php
+++ b/src/Symfony/Component/Intl/Timezones.php
@@ -36,12 +36,18 @@ public static function exists(string $timezone): bool
 
             return true;
         } catch (MissingResourceException $e) {
-            return false;
+            try {
+                new \DateTimeZone($timezone);
+
+                return true;
+            } catch (\Exception $e) {
+                return false;
+            }
         }
     }
 
     /**
-     * @throws MissingResourceException if the timezone identifier does not exists
+     * @throws MissingResourceException if the timezone identifier does not exist or is an alias
      */
     public static function getName(string $timezone, string $displayLocale = null): string
     {
@@ -57,7 +63,7 @@ public static function getNames(string $displayLocale = null): array
     }
 
     /**
-     * @throws \Exception       if the timezone identifier does not exists
+     * @throws \Exception       if the timezone identifier does not exist
      * @throws RuntimeException if there's no timezone DST transition information available
      */
     public static function getRawOffset(string $timezone, int $timestamp = null): int
@@ -92,7 +98,7 @@ public static function getCountryCode(string $timezone): string
     }
 
     /**
-     * @throws MissingResourceException if the country code does not exists
+     * @throws MissingResourceException if the country code does not exist
      */
     public static function forCountryCode(string $country): array
     {
diff --git a/src/Symfony/Component/Validator/Constraints/LocaleValidator.php b/src/Symfony/Component/Validator/Constraints/LocaleValidator.php
index 244d0f554ba0..2a48c0f5ef12 100644
--- a/src/Symfony/Component/Validator/Constraints/LocaleValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/LocaleValidator.php
@@ -11,10 +11,10 @@
 
 namespace Symfony\Component\Validator\Constraints;
 
-use Symfony\Component\Intl\Intl;
 use Symfony\Component\Intl\Locales;
 use Symfony\Component\Validator\Constraint;
 use Symfony\Component\Validator\ConstraintValidator;
+use Symfony\Component\Validator\Exception\LogicException;
 use Symfony\Component\Validator\Exception\UnexpectedTypeException;
 use Symfony\Component\Validator\Exception\UnexpectedValueException;
 
@@ -42,13 +42,17 @@ public function validate($value, Constraint $constraint)
             throw new UnexpectedValueException($value, 'string');
         }
 
+        if (!class_exists(Locales::class)) {
+            throw new LogicException('The "symfony/intl" component is required to use the Locale constraint.');
+        }
+
         $inputValue = (string) $value;
         $value = $inputValue;
         if ($constraint->canonicalize) {
             $value = \Locale::canonicalize($value);
         }
 
-        if (!Locales::exists($value) && !\in_array($value, Locales::getAliases(), true)) {
+        if (!Locales::exists($value)) {
             $this->context->buildViolation($constraint->message)
                 ->setParameter('{{ value }}', $this->formatValue($inputValue))
                 ->setCode(Locale::NO_SUCH_LOCALE_ERROR)
diff --git a/src/Symfony/Component/Validator/Constraints/TimezoneValidator.php b/src/Symfony/Component/Validator/Constraints/TimezoneValidator.php
index ac0d751a4532..d4261ff376c5 100644
--- a/src/Symfony/Component/Validator/Constraints/TimezoneValidator.php
+++ b/src/Symfony/Component/Validator/Constraints/TimezoneValidator.php
@@ -54,19 +54,10 @@ public function validate($value, Constraint $constraint)
             return;
         }
 
-        if ($constraint->countryCode) {
-            $phpTimezoneIds = @\DateTimeZone::listIdentifiers($constraint->zone, $constraint->countryCode) ?: [];
-            try {
-                $intlTimezoneIds = Timezones::forCountryCode($constraint->countryCode);
-            } catch (MissingResourceException $e) {
-                $intlTimezoneIds = [];
-            }
-        } else {
-            $phpTimezoneIds = \DateTimeZone::listIdentifiers($constraint->zone);
-            $intlTimezoneIds = self::getIntlTimezones($constraint->zone);
-        }
-
-        if (\in_array($value, $phpTimezoneIds, true) || \in_array($value, $intlTimezoneIds, true)) {
+        if (
+            \in_array($value, self::getPhpTimezones($constraint->zone, $constraint->countryCode), true) ||
+            \in_array($value, self::getIntlTimezones($constraint->zone, $constraint->countryCode), true)
+        ) {
             return;
         }
 
@@ -106,8 +97,29 @@ protected function formatValue($value, $format = 0)
         return array_search($value, (new \ReflectionClass(\DateTimeZone::class))->getConstants(), true) ?: $value;
     }
 
-    private static function getIntlTimezones(int $zone): array
+    private static function getPhpTimezones(int $zone, string $countryCode = null): array
     {
+        if (null !== $countryCode) {
+            return @\DateTimeZone::listIdentifiers($zone, $countryCode) ?: [];
+        }
+
+        return \DateTimeZone::listIdentifiers($zone);
+    }
+
+    private static function getIntlTimezones(int $zone, string $countryCode = null): array
+    {
+        if (!class_exists(Timezones::class)) {
+            return [];
+        }
+
+        if (null !== $countryCode) {
+            try {
+                return Timezones::forCountryCode($countryCode);
+            } catch (MissingResourceException $e) {
+                return [];
+            }
+        }
+
         $timezones = Timezones::getIds();
 
         if (\DateTimeZone::ALL === (\DateTimeZone::ALL & $zone)) {
diff --git a/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php b/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php
index 381d690bb84e..8dfeb48464f2 100644
--- a/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php
+++ b/src/Symfony/Component/Validator/Tests/Constraints/LocaleValidatorTest.php
@@ -111,7 +111,8 @@ public function getValidLocales()
             ['pt', ['canonicalize' => true]],
             ['pt_PT', ['canonicalize' => true]],
             ['zh_Hans', ['canonicalize' => true]],
-            ['fil_PH', ['canonicalize' => true]],
+            ['tl_PH', ['canonicalize' => true]],
+            ['fil_PH', ['canonicalize' => true]], // alias for "tl_PH"
         ];
     }