diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index f8a3293b1293..7d2535095ea4 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -591,7 +591,7 @@ public function isRunning()
      */
     public function stop($timeout=10)
     {
-        $timeoutMicro = (int) $timeout*10E6;
+        $timeoutMicro = (int) $timeout*1E6;
         if ($this->isRunning()) {
             proc_terminate($this->process);
             $time = 0;
@@ -600,6 +600,10 @@ public function stop($timeout=10)
                 usleep(1000);
             }
 
+            if (!defined('PHP_WINDOWS_VERSION_BUILD') && $this->isRunning()) {
+                proc_terminate($this->process, SIGKILL);
+            }
+
             foreach ($this->pipes as $pipe) {
                 fclose($pipe);
             }
diff --git a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
index 51d51f40b87b..7f622d38ac63 100644
--- a/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
+++ b/src/Symfony/Component/Process/Tests/AbstractProcessTest.php
@@ -44,6 +44,31 @@ public function testNullTimeout()
         $this->assertNull($p->getTimeout());
     }
 
+    public function testStopWithTimeoutIsActuallyWorking()
+    {
+        if (defined('PHP_WINDOWS_VERSION_BUILD')) {
+            $this->markTestSkipped('Stop with timeout does not work on windows, it requires posix signals');
+        }
+        if (!function_exists('pcntl_signal')) {
+            $this->markTestSkipped('This test require pcntl_signal function');
+        }
+
+        // exec is mandatory here since we send a signal to the process
+        // see https://github.com/symfony/symfony/issues/5030 about prepending
+        // command with exec
+        $p = $this->getProcess('exec php '.__DIR__.'/NonStopableProcess.php 3');
+        $p->start();
+        usleep(100000);
+        $start = microtime(true);
+        $p->stop(1.1);
+        while ($p->isRunning()) {
+            usleep(1000);
+        }
+        $duration = microtime(true) - $start;
+
+        $this->assertLessThan(1.3, $duration);
+    }
+
     /**
      * tests results from sub processes
      *
diff --git a/src/Symfony/Component/Process/Tests/NonStopableProcess.php b/src/Symfony/Component/Process/Tests/NonStopableProcess.php
new file mode 100644
index 000000000000..a4db838256af
--- /dev/null
+++ b/src/Symfony/Component/Process/Tests/NonStopableProcess.php
@@ -0,0 +1,37 @@
+<?php
+
+/**
+ * Runs a PHP script that can be stopped only with a SIGKILL (9) signal for 3 seconds
+ *
+ * @args duration Run this script with a custom duration
+ *
+ * @example `php NonStopableProcess.php 42` will run the script for 42 seconds
+ */
+
+function handleSignal($signal)
+{
+    switch ($signal) {
+        case SIGTERM:
+            $name = 'SIGTERM';
+            break;
+        case SIGINT:
+            $name = 'SIGINT';
+            break;
+        default:
+            $name = $signal . ' (unknown)';
+            break;
+    }
+
+    echo "received signal $name\n";
+}
+
+declare(ticks=1);
+pcntl_signal(SIGTERM, 'handleSignal');
+pcntl_signal(SIGINT, 'handleSignal');
+
+$duration = isset($argv[1]) ? (int) $argv[1] : 3;
+$start = microtime(true);
+
+while ($duration > (microtime(true) - $start)) {
+    usleep(1000);
+}