diff --git a/src/Symfony/Component/Process/Process.php b/src/Symfony/Component/Process/Process.php
index e0f49a7e3b..157499d10f 100644
--- a/src/Symfony/Component/Process/Process.php
+++ b/src/Symfony/Component/Process/Process.php
@@ -378,7 +378,11 @@ class Process
 
         $this->readPipes(false, '\\' === DIRECTORY_SEPARATOR ? !$this->processInformation['running'] : true);
 
-        return $this->stdout;
+        if (false === $ret = stream_get_contents($this->stdout, -1, 0)) {
+            return '';
+        }
+
+        return $ret;
     }
 
     /**
@@ -395,16 +399,13 @@ class Process
     {
         $this->requireProcessIsStarted(__FUNCTION__);
 
-        $data = $this->getOutput();
-
-        $latest = substr($data, $this->incrementalOutputOffset);
+        $latest = stream_get_contents($this->stdout, -1, $this->incrementalOutputOffset);
+        $this->incrementalOutputOffset = ftell($this->stdout);
 
         if (false === $latest) {
             return '';
         }
 
-        $this->incrementalOutputOffset = strlen($data);
-
         return $latest;
     }
 
@@ -421,7 +422,11 @@ class Process
 
         $this->readPipes(false, '\\' === DIRECTORY_SEPARATOR ? !$this->processInformation['running'] : true);
 
-        return $this->stderr;
+        if (false === $ret = stream_get_contents($this->stderr, -1, 0)) {
+            return '';
+        }
+
+        return $ret;
     }
 
     /**
@@ -439,16 +444,13 @@ class Process
     {
         $this->requireProcessIsStarted(__FUNCTION__);
 
-        $data = $this->getErrorOutput();
-
-        $latest = substr($data, $this->incrementalErrorOutputOffset);
+        $latest = stream_get_contents($this->stderr, -1, $this->incrementalErrorOutputOffset);
+        $this->incrementalErrorOutputOffset = ftell($this->stderr);
 
         if (false === $latest) {
             return '';
         }
 
-        $this->incrementalErrorOutputOffset = strlen($data);
-
         return $latest;
     }
 
@@ -666,21 +668,29 @@ class Process
     /**
      * Adds a line to the STDOUT stream.
      *
+     * @internal
+     *
      * @param string $line The line to append
      */
     public function addOutput($line)
     {
-        $this->stdout .= $line;
+        fseek($this->stdout, 0, SEEK_END);
+        fwrite($this->stdout, $line);
+        fseek($this->stdout, $this->incrementalOutputOffset);
     }
 
     /**
      * Adds a line to the STDERR stream.
      *
+     * @internal
+     *
      * @param string $line The line to append
      */
     public function addErrorOutput($line)
     {
-        $this->stderr .= $line;
+        fseek($this->stderr, 0, SEEK_END);
+        fwrite($this->stderr, $line);
+        fseek($this->stderr, $this->incrementalErrorOutputOffset);
     }
 
     /**
@@ -1126,8 +1136,8 @@ class Process
         $this->exitcode = null;
         $this->fallbackStatus = array();
         $this->processInformation = null;
-        $this->stdout = null;
-        $this->stderr = null;
+        $this->stdout = fopen('php://temp/maxmemory:'.(1024 * 1024), 'wb+');
+        $this->stderr = fopen('php://temp/maxmemory:'.(1024 * 1024), 'wb+');
         $this->process = null;
         $this->latestSignal = null;
         $this->status = self::STATUS_READY;