diff --git a/src/Symfony/Bundle/FrameworkBundle/Resources/config/console.xml b/src/Symfony/Bundle/FrameworkBundle/Resources/config/console.xml
index 9553d4d60d7ce..4369a5549f367 100644
--- a/src/Symfony/Bundle/FrameworkBundle/Resources/config/console.xml
+++ b/src/Symfony/Bundle/FrameworkBundle/Resources/config/console.xml
@@ -113,6 +113,13 @@
             <tag name="console.command" command="translation:update" />
         </service>
 
+        <service id="console.command.translation_intl_convert" class="Symfony\Component\Translation\Command\IntlConvertCommand">
+            <argument type="service" id="translation.writer" />
+            <argument type="service" id="translation.reader" />
+            <tag name="console.command" command="translation:convert-to-intl-messages" />
+        </service>
+
+
         <service id="console.command.workflow_dump" class="Symfony\Bundle\FrameworkBundle\Command\WorkflowDumpCommand">
             <tag name="console.command" command="workflow:dump" />
         </service>
diff --git a/src/Symfony/Component/Translation/Command/IntlConvertCommand.php b/src/Symfony/Component/Translation/Command/IntlConvertCommand.php
new file mode 100644
index 0000000000000..745881c634273
--- /dev/null
+++ b/src/Symfony/Component/Translation/Command/IntlConvertCommand.php
@@ -0,0 +1,96 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Translation\Command;
+
+use Symfony\Component\Console\Command\Command;
+use Symfony\Component\Console\Input\InputArgument;
+use Symfony\Component\Console\Input\InputInterface;
+use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\OutputInterface;
+use Symfony\Component\Console\Style\SymfonyStyle;
+use Symfony\Component\HttpKernel\KernelInterface;
+use Symfony\Component\Translation\MessageCatalogue;
+use Symfony\Component\Translation\Reader\TranslationReaderInterface;
+use Symfony\Component\Translation\Util\IntlMessageConverter;
+use Symfony\Component\Translation\Writer\TranslationWriterInterface;
+
+/**
+ * Convert to Intl styled message format.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+class IntlConvertCommand extends Command
+{
+    protected static $defaultName = 'translation:convert-to-intl-messages';
+
+    private $writer;
+    private $reader;
+
+    public function __construct(TranslationWriterInterface $writer, TranslationReaderInterface $reader)
+    {
+        parent::__construct();
+
+        $this->writer = $writer;
+        $this->reader = $reader;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function configure()
+    {
+        $this
+            ->setDescription('Convert from Symfony 3 plural format to ICU message format.')
+            ->addArgument('locale', InputArgument::REQUIRED, 'The locale')
+            ->addArgument('path', null, 'A file or a directory')
+            ->addOption('domain', null, InputOption::VALUE_OPTIONAL, 'The messages domain')
+            ->addOption('output-format', null, InputOption::VALUE_OPTIONAL, 'Override the default output format', 'xlf')
+        ;
+    }
+
+    protected function execute(InputInterface $input, OutputInterface $output)
+    {
+        $io = new SymfonyStyle($input, $output);
+        $path = $input->getArgument('path');
+        $locale = $input->getArgument('locale');
+        $domain = $input->getOption('domain');
+        /** @var KernelInterface $kernel */
+        $kernel = $this->getApplication()->getKernel();
+
+        // Define Root Paths
+        $transPaths = $kernel->getProjectDir().\DIRECTORY_SEPARATOR.'translations';
+        if (null !== $path) {
+            $transPaths = $path;
+        }
+
+        // load any existing messages from the translation files
+        $currentCatalogue = new MessageCatalogue($locale);
+        if (!is_dir($transPaths)) {
+            throw new \LogicException('The "path" must be a directory.');
+        }
+        $this->reader->read($transPaths, $currentCatalogue);
+
+        $allMessages = $currentCatalogue->all($domain);
+        if (null !== $domain) {
+            $allMessages = array($domain => $allMessages);
+        }
+
+        $updated = array();
+        foreach ($allMessages as $messageDomain => $messages) {
+            foreach ($messages as $key => $message) {
+                $updated[$messageDomain][$key] = IntlMessageConverter::convert($message);
+            }
+        }
+
+        $this->writer->write(new MessageCatalogue($locale, $updated), $input->getOption('output-format'), array('path' => $transPaths));
+    }
+}
diff --git a/src/Symfony/Component/Translation/Tests/Util/IntlMessageConverterTest.php b/src/Symfony/Component/Translation/Tests/Util/IntlMessageConverterTest.php
new file mode 100644
index 0000000000000..7aef95df822b8
--- /dev/null
+++ b/src/Symfony/Component/Translation/Tests/Util/IntlMessageConverterTest.php
@@ -0,0 +1,96 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Symfony\Component\Translation\Tests\Util;
+
+use PHPUnit\Framework\TestCase;
+use Symfony\Component\Translation\Util\IntlMessageConverter;
+
+class IntlMessageConverterTest extends TestCase
+{
+    /**
+     * @dataProvider getTestData
+     */
+    public function testConvert($input, $output)
+    {
+        $result = IntlMessageConverter::convert($input);
+        $this->assertEquals($output, $result);
+    }
+
+    public function testConvertWithCustomDelimiter()
+    {
+        $result = IntlMessageConverter::convert('Foo #var# bar', '#');
+        $this->assertEquals('Foo {var} bar', $result);
+
+        $result = IntlMessageConverter::convert('{0} Foo #var# bar | {1} Bar #var# foo', '#');
+        $this->assertEquals(
+            <<<ICU
+{ COUNT, plural,
+  =0 {Foo {var} bar}
+  =1 {Bar {var} foo}
+}
+ICU
+, $result);
+    }
+
+    /**
+     * We cannot use negative Inf together with positive Inf.
+     */
+    public function testImpossibleConvert()
+    {
+        $this->expectException(\LogicException::class);
+        IntlMessageConverter::convert(']-Inf, -2[ Negative|]1,Inf[ Positive');
+    }
+
+    public function getTestData()
+    {
+        yield array('|', '|');
+        yield array(
+            '{0} There are no apples|{1} There is one apple|]1,Inf[ There %name% are %count% apples',
+            <<<ICU
+{ COUNT, plural,
+  =0 {There are no apples}
+  =1 {There is one apple}
+  other {There {name} are # apples}
+}
+ICU
+            );
+        yield array('foo', 'foo');
+        yield array('Hello %username%', 'Hello {username}');
+
+        yield array(
+            ']-7, -2] Negative|[2, 7] Small|]10,Inf[ Many',
+            <<<ICU
+{ COUNT, plural,
+  =-6 {Negative}
+  =-5 {Negative}
+  =-4 {Negative}
+  =-3 {Negative}
+  =-2 {Negative}
+  =2 {Small}
+  =3 {Small}
+  =4 {Small}
+  =5 {Small}
+  =6 {Small}
+  =7 {Small}
+  other {Many}
+}
+ICU
+        );
+
+        // Test overlapping, make sure we have the same behaviour as Symfony
+        yield array(
+            '[2,5] Small|]3,Inf[ Many',
+            <<<ICU
+{ COUNT, plural,
+  =2 {Small}
+  =3 {Small}
+  =4 {Small}
+  =5 {Small}
+  other {Many}
+}
+ICU
+        );
+    }
+}
diff --git a/src/Symfony/Component/Translation/Util/IntlMessageConverter.php b/src/Symfony/Component/Translation/Util/IntlMessageConverter.php
new file mode 100644
index 0000000000000..0867a963fd11b
--- /dev/null
+++ b/src/Symfony/Component/Translation/Util/IntlMessageConverter.php
@@ -0,0 +1,128 @@
+<?php
+
+/*
+ * This file is part of the Symfony package.
+ *
+ * (c) Fabien Potencier <fabien@symfony.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Symfony\Component\Translation\Util;
+
+/**
+ * Convert from Symfony 3's plural syntax to Intl message format.
+ * {@link https://messageformat.github.io/messageformat/page-guide}.
+ *
+ * @author Tobias Nyholm <tobias.nyholm@gmail.com>
+ */
+class IntlMessageConverter
+{
+    public static function convert(string $message, string $variableDelimiter = '%'): string
+    {
+        $array = self::getMessageArray($message);
+        if (empty($array)) {
+            return $message;
+        }
+
+        if (1 === \count($array) && isset($array[0])) {
+            return self::replaceVariables($message, $variableDelimiter);
+        }
+
+        $icu = self::buildIcuString($array, $variableDelimiter);
+
+        return $icu;
+    }
+
+    /**
+     * Get an ICU like array.
+     */
+    private static function getMessageArray(string $message): array
+    {
+        if (preg_match('/^\|++$/', $message)) {
+            // If the message only contains pipes ("|||")
+            return array();
+        } elseif (preg_match_all('/(?:\|\||[^\|])++/', $message, $matches)) {
+            $parts = $matches[0];
+        } else {
+            throw new \LogicException(sprintf('Input string "%s" is not supported.', $message));
+        }
+
+        $intervalRegexp = <<<'EOF'
+/^(?P<interval>
+    ({\s*
+        (\-?\d+(\.\d+)?[\s*,\s*\-?\d+(\.\d+)?]*)
+    \s*})
+
+        |
+
+    (?P<left_delimiter>[\[\]])
+        \s*
+        (?P<left>-Inf|\-?\d+(\.\d+)?)
+        \s*,\s*
+        (?P<right>\+?Inf|\-?\d+(\.\d+)?)
+        \s*
+    (?P<right_delimiter>[\[\]])
+)\s*(?P<message>.*?)$/xs
+EOF;
+
+        $standardRules = array();
+        foreach ($parts as $part) {
+            $part = trim(str_replace('||', '|', $part));
+
+            // try to match an explicit rule, then fallback to the standard ones
+            if (preg_match($intervalRegexp, $part, $matches)) {
+                if ($matches[2]) {
+                    foreach (explode(',', $matches[3]) as $n) {
+                        $standardRules['='.$n] = $matches['message'];
+                    }
+                } else {
+                    $leftNumber = '-Inf' === $matches['left'] ? -INF : (float) $matches['left'];
+                    $rightNumber = \is_numeric($matches['right']) ? (float) $matches['right'] : INF;
+
+                    $leftNumber = ('[' === $matches['left_delimiter'] ? $leftNumber : 1 + $leftNumber);
+                    $rightNumber = (']' === $matches['right_delimiter'] ? 1 + $rightNumber : $rightNumber);
+
+                    if ($leftNumber !== -INF && INF !== $rightNumber) {
+                        for ($i = $leftNumber; $i < $rightNumber; ++$i) {
+                            $standardRules['='.$i] = $matches['message'];
+                        }
+                    } else {
+                        // $rightNumber is INF or $leftNumber is -INF
+                        if (isset($standardRules['other'])) {
+                            throw new \LogicException(sprintf('%s does not support converting messages with both "-Inf" and "Inf". Message: "%s"', __CLASS__, $message));
+                        }
+                        $standardRules['other'] = $matches['message'];
+                    }
+                }
+            } elseif (preg_match('/^\w+\:\s*(.*?)$/', $part, $matches)) {
+                $standardRules[] = $matches[1];
+            } else {
+                $standardRules[] = $part;
+            }
+        }
+
+        return $standardRules;
+    }
+
+    private static function buildIcuString(array $data, string $variableDelimiter): string
+    {
+        $icu = "{ COUNT, plural,\n";
+        foreach ($data as $key => $message) {
+            $message = strtr($message, array('%count%' => '#'));
+            $message = self::replaceVariables($message, $variableDelimiter);
+            $icu .= sprintf("  %s {%s}\n", $key, $message);
+        }
+        $icu .= '}';
+
+        return $icu;
+    }
+
+    private static function replaceVariables(string $message, string $variableDelimiter): string
+    {
+        $regex = sprintf('|%s(.*?)%s|s', $variableDelimiter, $variableDelimiter);
+
+        return preg_replace($regex, '{$1}', $message);
+    }
+}