diff --git a/.travis.yml b/.travis.yml
index c38702f..f27e7b6 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -17,6 +17,40 @@ env:
   - DEPS=highest
 
 install:
+  - git clone https://github.com/libuv/libuv;
+    pushd libuv;
+    git checkout $(git describe --tags);
+    ./autogen.sh;
+    ./configure --prefix=$(dirname `pwd`)/libuv-install;
+    make;
+    make install;
+    popd;
+    git clone https://github.com/bwoebi/php-uv.git;
+    pushd php-uv;
+    phpize;
+    ./configure --with-uv=$(dirname `pwd`)/libuv-install;
+    make;
+    make install;
+    popd;
+    echo "extension=uv.so" >> "$(php -r 'echo php_ini_loaded_file();')";
+    
+  - curl -LS https://pecl.php.net/get/ev | tar -xz;
+    pushd ev-*;
+    phpize;
+    ./configure;
+    make;
+    make install;
+    popd;
+    echo "extension=ev.so" >> "$(php -r 'echo php_ini_loaded_file();')";
+  - curl -LS https://pecl.php.net/get/event | tar -xz;
+    pushd event-*;
+    phpize;
+    ./configure --with-event-core --with-event-extra --with-event-pthreads;
+    make;
+    make install;
+    popd;
+    echo "extension=event.so" >> "$(php -r 'echo php_ini_loaded_file();')";
+
   - if [ "$DEPS" = "lowest" ]; then
       composer update -n --prefer-source --prefer-lowest;
     else
diff --git a/lib/EvLoop.php b/lib/EvLoop.php
new file mode 100644
index 0000000..cec20ea
--- /dev/null
+++ b/lib/EvLoop.php
@@ -0,0 +1,190 @@
+<?php
+
+namespace Amp\Loop;
+
+use Amp\Loop\Internal\Watcher;
+
+class EvLoop extends Loop {
+    /** @var \EvLoop */
+    private $handle;
+
+    /** @var \EvWatcher[] */
+    private $events = [];
+
+    /** @var callable */
+    private $ioCallback;
+
+    /** @var callable */
+    private $timerCallback;
+    
+    /** @var callable */
+    private $signalCallback;
+    
+    /** @var \EvSignal[] */
+    private $signals = [];
+    
+    /** @var \EvSignal[]|null */
+    private static $activeSignals;
+
+    public static function supported() {
+        return \extension_loaded("ev");
+    }
+
+    public function __construct() {
+        $this->handle = new \EvLoop;
+        
+        if (self::$activeSignals === null) {
+            self::$activeSignals = &$this->signals;
+        }
+
+        $this->ioCallback = function (\EvIO $event) {
+            /** @var \Amp\Loop\Internal\Watcher $watcher */
+            $watcher = $event->data;
+
+            $callback = $watcher->callback;
+            $callback($watcher->id, $watcher->value, $watcher->data);
+        };
+
+        $this->timerCallback = function (\EvTimer $event) {
+            /** @var \Amp\Loop\Internal\Watcher $watcher */
+            $watcher = $event->data;
+
+            if ($watcher->type & Watcher::DELAY) {
+                $this->cancel($watcher->id);
+            }
+
+            $callback = $watcher->callback;
+            $callback($watcher->id, $watcher->data);
+        };
+
+        $this->signalCallback = function (\EvSignal $event) {
+            /** @var \Amp\Loop\Internal\Watcher $watcher */
+            $watcher = $event->data;
+
+            $callback = $watcher->callback;
+            $callback($watcher->id, $watcher->value, $watcher->data);
+        };
+    }
+
+    public function __destruct() {
+        foreach ($this->events as $event) {
+            $event->stop();
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function run() {
+        $active = self::$activeSignals;
+        
+        foreach ($active as $event) {
+            $event->stop();
+        }
+        
+        self::$activeSignals = &$this->signals;
+        
+        foreach ($this->signals as $event) {
+            $event->start();
+        }
+        
+        try {
+            parent::run();
+        } finally {
+            foreach ($this->signals as $event) {
+                $event->stop();
+            }
+            
+            self::$activeSignals = &$active;
+            
+            foreach ($active as $event) {
+                $event->start();
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function stop() {
+        $this->handle->stop();
+        parent::stop();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function dispatch($blocking) {
+        $this->handle->run($blocking ? \Ev::RUN_ONCE : \Ev::RUN_ONCE | \Ev::RUN_NOWAIT);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function activate(array $watchers) {
+        foreach ($watchers as $watcher) {
+            if (!isset($this->events[$id = $watcher->id])) {
+                switch ($watcher->type) {
+                    case Watcher::READABLE:
+                        $this->events[$id] = $this->handle->io($watcher->value, \Ev::READ, $this->ioCallback, $watcher);
+                        break;
+
+                    case Watcher::WRITABLE:
+                        $this->events[$id] = $this->handle->io($watcher->value, \Ev::WRITE, $this->ioCallback, $watcher);
+                        break;
+
+                    case Watcher::DELAY:
+                    case Watcher::REPEAT:
+                        $interval = $watcher->value / self::MILLISEC_PER_SEC;
+                        $this->events[$id] = $this->handle->timer(
+                            $interval,
+                            $watcher->type & Watcher::REPEAT ? $interval : 0,
+                            $this->timerCallback,
+                            $watcher
+                        );
+                        break;
+
+                    case Watcher::SIGNAL:
+                        $this->events[$id] = $this->handle->signal($watcher->value, $this->signalCallback, $watcher);
+                        break;
+
+                    default:
+                        throw new \DomainException("Unknown watcher type");
+                }
+            } else {
+                $this->events[$id]->start();
+            }
+
+            if ($watcher->type === Watcher::SIGNAL) {
+                $this->signals[$id] = $this->events[$id];
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function deactivate(Watcher $watcher) {
+        if (isset($this->events[$id = $watcher->id])) {
+            $this->events[$id]->stop();
+            if ($watcher->type === Watcher::SIGNAL) {
+                unset($this->signals[$id]);
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function cancel($watcherIdentifier) {
+        parent::cancel($watcherIdentifier);
+        unset($this->events[$watcherIdentifier]);
+    }
+    
+    /**
+     * {@inheritdoc}
+     */
+    public function getHandle() {
+        return $this->handle;
+    }
+}
diff --git a/lib/EventLoop.php b/lib/EventLoop.php
new file mode 100644
index 0000000..0f08eca
--- /dev/null
+++ b/lib/EventLoop.php
@@ -0,0 +1,213 @@
+<?php
+
+namespace Amp\Loop;
+
+use Amp\Loop\Internal\Watcher;
+
+class EventLoop extends Loop {
+    /** @var \EventBase */
+    private $handle;
+
+    /** @var \Event[] */
+    private $events = [];
+
+    /** @var callable */
+    private $ioCallback;
+
+    /** @var callable */
+    private $timerCallback;
+    
+    /** @var callable */
+    private $signalCallback;
+    
+    /** @var \Event[] */
+    private $signals = [];
+    
+    /** @var \Event[]|null */
+    private static $activeSignals;
+
+    public static function supported() {
+        return \extension_loaded("event");
+    }
+
+    public function __construct() {
+        $this->handle = new \EventBase;
+    
+        if (self::$activeSignals === null) {
+            self::$activeSignals = &$this->signals;
+        }
+        
+        $this->ioCallback = function ($resource, $what, Watcher $watcher) {
+            $callback = $watcher->callback;
+            $callback($watcher->id, $watcher->value, $watcher->data);
+        };
+
+        $this->timerCallback = function ($resource, $what, Watcher $watcher) {
+            if ($watcher->type & Watcher::DELAY) {
+                $this->cancel($watcher->id);
+            }
+
+            $callback = $watcher->callback;
+            $callback($watcher->id, $watcher->data);
+        };
+
+        $this->signalCallback = function ($signum, $what, Watcher $watcher) {
+            $callback = $watcher->callback;
+            $callback($watcher->id, $watcher->value, $watcher->data);
+        };
+    }
+    
+    public function __destruct() {
+        foreach ($this->events as $event) {
+            $event->free();
+        }
+    }
+    
+    /**
+     * {@inheritdoc}
+     */
+    public function run() {
+        $active = self::$activeSignals;
+        
+        foreach ($active as $event) {
+            $event->del();
+        }
+        
+        self::$activeSignals = &$this->signals;
+        
+        foreach ($this->signals as $event) {
+            $event->add();
+        }
+        
+        try {
+            parent::run();
+        } finally {
+            foreach ($this->signals as $event) {
+                $event->del();
+            }
+            
+            self::$activeSignals = &$active;
+            
+            foreach ($active as $event) {
+                $event->add();
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function stop() {
+        $this->handle->stop();
+        parent::stop();
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function dispatch($blocking) {
+        $this->handle->loop($blocking ? \EventBase::LOOP_ONCE : \EventBase::LOOP_ONCE | \EventBase::LOOP_NONBLOCK);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function activate(array $watchers) {
+        foreach ($watchers as $watcher) {
+            if (!isset($this->events[$id = $watcher->id])) {
+                switch ($watcher->type) {
+                    case Watcher::READABLE:
+                        $this->events[$id] = new \Event(
+                            $this->handle,
+                            $watcher->value,
+                            \Event::READ | \Event::PERSIST,
+                            $this->ioCallback,
+                            $watcher
+                        );
+                        break;
+
+                    case Watcher::WRITABLE:
+                        $this->events[$id] = new \Event(
+                            $this->handle,
+                            $watcher->value,
+                            \Event::WRITE | \Event::PERSIST,
+                            $this->ioCallback,
+                            $watcher
+                        );
+                        break;
+
+                    case Watcher::DELAY:
+                    case Watcher::REPEAT:
+                        $this->events[$id] = new \Event(
+                            $this->handle,
+                            -1,
+                            \Event::TIMEOUT | \Event::PERSIST,
+                            $this->timerCallback,
+                            $watcher
+                        );
+                        break;
+
+                    case Watcher::SIGNAL:
+                        $this->events[$id] = new \Event(
+                            $this->handle,
+                            $watcher->value,
+                            \Event::SIGNAL | \Event::PERSIST,
+                            $this->signalCallback,
+                            $watcher
+                        );
+                        break;
+
+                    default:
+                        throw new \DomainException("Unknown watcher type");
+                }
+            }
+            
+            switch ($watcher->type) {
+                case Watcher::DELAY:
+                case Watcher::REPEAT:
+                    $this->events[$id]->add($watcher->value / self::MILLISEC_PER_SEC);
+                    break;
+                    
+                case Watcher::SIGNAL:
+                    $this->signals[$id] = $this->events[$id];
+                    // No break
+                
+                default:
+                    $this->events[$id]->add();
+                    break;
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function deactivate(Watcher $watcher) {
+        if (isset($this->events[$id = $watcher->id])) {
+            $this->events[$id]->del();
+            
+            if ($watcher->type === Watcher::SIGNAL) {
+                unset($this->signals[$id]);
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function cancel($watcherIdentifier) {
+        parent::cancel($watcherIdentifier);
+        
+        if (isset($this->events[$watcherIdentifier])) {
+            $this->events[$watcherIdentifier]->free();
+            unset($this->events[$watcherIdentifier]);
+        }
+    }
+    
+    /**
+     * {@inheritdoc}
+     */
+    public function getHandle() {
+        return $this->handle;
+    }
+}
diff --git a/lib/Internal/Watcher.php b/lib/Internal/Watcher.php
new file mode 100644
index 0000000..7903347
--- /dev/null
+++ b/lib/Internal/Watcher.php
@@ -0,0 +1,43 @@
+<?php
+
+namespace Amp\Loop\Internal;
+
+class Watcher {
+    const DEFER    = 0b00000001;
+    const TIMER    = 0b00000110;
+    const DELAY    = 0b00000010;
+    const REPEAT   = 0b00000100;
+    const IO       = 0b00011000;
+    const READABLE = 0b00001000;
+    const WRITABLE = 0b00010000;
+    const SIGNAL   = 0b00100000;
+
+    /** @var int */
+    public $type;
+
+    /** @var bool */
+    public $enabled = true;
+
+    /** @var bool */
+    public $referenced = true;
+
+    /** @var string */
+    public $id;
+
+    /** @var callable */
+    public $callback;
+
+    /**
+     * Data provided to the watcher callback.
+     *
+     * @var mixed
+     */
+    public $data;
+
+    /**
+     * Watcher-dependent value storage. Stream for IO watchers, signo for signal watchers, interval for timers.
+     *
+     * @var mixed
+     */
+    public $value;
+}
diff --git a/lib/Loop.php b/lib/Loop.php
new file mode 100644
index 0000000..534397f
--- /dev/null
+++ b/lib/Loop.php
@@ -0,0 +1,415 @@
+<?php
+
+namespace Amp\Loop;
+
+use Amp\Loop\Internal\Watcher;
+use AsyncInterop\Loop\Driver;
+use AsyncInterop\Loop\InvalidWatcherException;
+
+abstract class Loop extends Driver {
+    // Don't use 1e3 / 1e6, they result in a float instead of int
+    const MILLISEC_PER_SEC = 1000;
+    const MICROSEC_PER_SEC = 1000000;
+
+    /** @var string */
+    private $nextId = "a";
+
+    /** @var \Amp\Loop\Internal\Watcher[] */
+    private $watchers = [];
+
+    /** @var \Amp\Loop\Internal\Watcher[] */
+    private $enableQueue = [];
+
+    /** @var \Amp\Loop\Internal\Watcher[] */
+    private $deferQueue = [];
+
+    /** @var \Amp\Loop\Internal\Watcher[] */
+    private $nextTickQueue = [];
+
+    /** @var callable|null */
+    private $errorHandler;
+
+    /** @var int */
+    private $running = 0;
+
+    /**
+     * {@inheritdoc}
+     */
+    public function run() {
+        $previous = $this->running;
+        ++$this->running;
+
+        try {
+            while ($this->running > $previous) {
+                if ($this->isEmpty()) {
+                    return;
+                }
+                $this->tick();
+            }
+        } finally {
+            $this->running = $previous;
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function stop() {
+        --$this->running > 0 ?: $this->running = 0;
+    }
+
+    /**
+     * @return bool True if no enabled and referenced watchers remain in the loop.
+     */
+    private function isEmpty() {
+        foreach ($this->watchers as $watcher) {
+            if ($watcher->enabled && $watcher->referenced) {
+                return false;
+            }
+        }
+
+        return true;
+    }
+
+    /**
+     * Executes a single tick of the event loop.
+     */
+    private function tick() {
+        $this->deferQueue = \array_merge($this->deferQueue, $this->nextTickQueue);
+        $this->nextTickQueue = [];
+
+        $this->activate($this->enableQueue);
+        $this->enableQueue = [];
+
+        try {
+            foreach ($this->deferQueue as $watcher) {
+                if (!isset($this->deferQueue[$watcher->id])) {
+                    continue; // Watcher disabled by another defer watcher.
+                }
+
+                unset($this->watchers[$watcher->id], $this->deferQueue[$watcher->id]);
+
+                $callback = $watcher->callback;
+                $callback($watcher->id, $watcher->data);
+            }
+
+            $this->dispatch(empty($this->nextTickQueue) && empty($this->enableQueue) && $this->running);
+
+        } catch (\Throwable $exception) {
+            if (null === $this->errorHandler) {
+                throw $exception;
+            }
+
+            $errorHandler = $this->errorHandler;
+            $errorHandler($exception);
+        } catch (\Exception $exception) { // @todo Remove when PHP 5.x support is no longer needed.
+            if (null === $this->errorHandler) {
+                throw $exception;
+            }
+
+            $errorHandler = $this->errorHandler;
+            $errorHandler($exception);
+        }
+    }
+
+    /**
+     * Dispatches any pending read/write, timer, and signal events.
+     *
+     * @param bool $blocking
+     */
+    abstract protected function dispatch($blocking);
+
+    /**
+     * Activates (enables) all the given watchers.
+     *
+     * @param \Amp\Loop\Internal\Watcher[] $watchers
+     */
+    abstract protected function activate(array $watchers);
+
+    /**
+     * Deactivates (disables) the given watcher.
+     *
+     * @param \Amp\Loop\Internal\Watcher $watcher
+     */
+    abstract protected function deactivate(Watcher $watcher);
+
+    /**
+     * {@inheritdoc}
+     */
+    public function defer(callable $callback, $data = null) {
+        $watcher = new Watcher;
+        $watcher->type = Watcher::DEFER;
+        $watcher->id = $this->nextId++;
+        $watcher->callback = $callback;
+        $watcher->data = $data;
+
+        $this->watchers[$watcher->id] = $watcher;
+        $this->nextTickQueue[$watcher->id] = $watcher;
+
+        return $watcher->id;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function delay($delay, callable $callback, $data = null) {
+        $delay = (int) $delay;
+
+        if ($delay < 0) {
+            throw new \InvalidArgumentException("Delay must be greater than or equal to zero");
+        }
+
+        $watcher = new Watcher;
+        $watcher->type = Watcher::DELAY;
+        $watcher->id = $this->nextId++;
+        $watcher->callback = $callback;
+        $watcher->value = $delay;
+        $watcher->data = $data;
+
+        $this->watchers[$watcher->id] = $watcher;
+        $this->enableQueue[$watcher->id] = $watcher;
+
+        return $watcher->id;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function repeat($interval, callable $callback, $data = null) {
+        $interval = (int) $interval;
+
+        if ($interval < 0) {
+            throw new \InvalidArgumentException("Interval must be greater than or equal to zero");
+        }
+
+        $watcher = new Watcher;
+        $watcher->type = Watcher::REPEAT;
+        $watcher->id = $this->nextId++;
+        $watcher->callback = $callback;
+        $watcher->value = $interval;
+        $watcher->data = $data;
+
+        $this->watchers[$watcher->id] = $watcher;
+        $this->enableQueue[$watcher->id] = $watcher;
+
+        return $watcher->id;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function onReadable($stream, callable $callback, $data = null) {
+        $watcher = new Watcher;
+        $watcher->type = Watcher::READABLE;
+        $watcher->id = $this->nextId++;
+        $watcher->callback = $callback;
+        $watcher->value = $stream;
+        $watcher->data = $data;
+
+        $this->watchers[$watcher->id] = $watcher;
+        $this->enableQueue[$watcher->id] = $watcher;
+
+        return $watcher->id;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function onWritable($stream, callable $callback, $data = null) {
+        $watcher = new Watcher;
+        $watcher->type = Watcher::WRITABLE;
+        $watcher->id = $this->nextId++;
+        $watcher->callback = $callback;
+        $watcher->value = $stream;
+        $watcher->data = $data;
+
+        $this->watchers[$watcher->id] = $watcher;
+        $this->enableQueue[$watcher->id] = $watcher;
+
+        return $watcher->id;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @throws \AsyncInterop\Loop\UnsupportedFeatureException If the pcntl extension is not available.
+     * @throws \RuntimeException If creating the backend signal handler fails.
+     */
+    public function onSignal($signo, callable $callback, $data = null) {
+        $watcher = new Watcher;
+        $watcher->type = Watcher::SIGNAL;
+        $watcher->id = $this->nextId++;
+        $watcher->callback = $callback;
+        $watcher->value = $signo;
+        $watcher->data = $data;
+
+        $this->watchers[$watcher->id] = $watcher;
+        $this->enableQueue[$watcher->id] = $watcher;
+
+        return $watcher->id;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function enable($watcherIdentifier) {
+        if (!isset($this->watchers[$watcherIdentifier])) {
+            throw new InvalidWatcherException($watcherIdentifier, "Cannot enable an invalid watcher identifier: '{$watcherIdentifier}'");
+        }
+
+        $watcher = $this->watchers[$watcherIdentifier];
+
+        if ($watcher->enabled) {
+            return; // Watcher already enabled.
+        }
+
+        $watcher->enabled = true;
+
+        switch ($watcher->type) {
+            case Watcher::DEFER:
+                $this->nextTickQueue[$watcher->id] = $watcher;
+                break;
+
+            default:
+                $this->enableQueue[$watcher->id] = $watcher;
+                break;
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function disable($watcherIdentifier) {
+        if (!isset($this->watchers[$watcherIdentifier])) {
+            return;
+        }
+
+        $watcher = $this->watchers[$watcherIdentifier];
+
+        if (!$watcher->enabled) {
+            return; // Watcher already disabled.
+        }
+
+        $watcher->enabled = false;
+        $id = $watcher->id;
+
+        switch ($watcher->type) {
+            case Watcher::DEFER:
+                if (isset($this->nextTickQueue[$id])) {
+                    // Watcher was only queued to be enabled.
+                    unset($this->nextTickQueue[$id]);
+                } else {
+                    unset($this->deferQueue[$id]);
+                }
+                break;
+
+            default:
+                if (isset($this->enableQueue[$id])) {
+                    // Watcher was only queued to be enabled.
+                    unset($this->enableQueue[$id]);
+                } else {
+                    $this->deactivate($watcher);
+                }
+                break;
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function cancel($watcherIdentifier) {
+        $this->disable($watcherIdentifier);
+        unset($this->watchers[$watcherIdentifier]);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function reference($watcherIdentifier) {
+        if (!isset($this->watchers[$watcherIdentifier])) {
+            throw new InvalidWatcherException($watcherIdentifier, "Cannot reference an invalid watcher identifier: '{$watcherIdentifier}'");
+        }
+
+        $this->watchers[$watcherIdentifier]->referenced = true;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function unreference($watcherIdentifier) {
+        if (!isset($this->watchers[$watcherIdentifier])) {
+            throw new InvalidWatcherException($watcherIdentifier, "Cannot unreference an invalid watcher identifier: '{$watcherIdentifier}'");
+        }
+
+        $this->watchers[$watcherIdentifier]->referenced = false;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function setErrorHandler(callable $callback = null) {
+        $previous = $this->errorHandler;
+        $this->errorHandler = $callback;
+        return $previous;
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getInfo() {
+        $watchers = [
+            "referenced"   => 0,
+            "unreferenced" => 0,
+        ];
+
+        $defer = $delay = $repeat = $onReadable = $onWritable = $onSignal = [
+            "enabled"  => 0,
+            "disabled" => 0,
+        ];
+
+        foreach ($this->watchers as $watcher) {
+            switch ($watcher->type) {
+                case Watcher::READABLE: $array = &$onReadable; break;
+                case Watcher::WRITABLE: $array = &$onWritable; break;
+                case Watcher::SIGNAL:   $array = &$onSignal; break;
+                case Watcher::DEFER:    $array = &$defer; break;
+                case Watcher::DELAY:    $array = &$delay; break;
+                case Watcher::REPEAT:   $array = &$repeat; break;
+
+                default: throw new \DomainException("Unknown watcher type");
+            }
+
+            if ($watcher->enabled) {
+                ++$array["enabled"];
+
+                if ($watcher->referenced) {
+                    ++$watchers["referenced"];
+                } else {
+                    ++$watchers["unreferenced"];
+                }
+            } else {
+                ++$array["disabled"];
+            }
+        }
+
+        return [
+            "watchers"    => $watchers,
+            "defer"       => $defer,
+            "delay"       => $delay,
+            "repeat"      => $repeat,
+            "on_readable" => $onReadable,
+            "on_writable" => $onWritable,
+            "on_signal"   => $onSignal,
+            "running"     => (bool) $this->running,
+        ];
+    }
+
+    /**
+     * Returns the same array of data as getInfo().
+     *
+     * @return array
+     */
+    public function __debugInfo() {
+        return $this->getInfo();
+    }
+}
diff --git a/src/Loop/Driver.php b/lib/Loop/Driver.php
similarity index 100%
rename from src/Loop/Driver.php
rename to lib/Loop/Driver.php
diff --git a/src/Loop/DriverFactory.php b/lib/Loop/DriverFactory.php
similarity index 100%
rename from src/Loop/DriverFactory.php
rename to lib/Loop/DriverFactory.php
diff --git a/src/Loop/InvalidWatcherException.php b/lib/Loop/InvalidWatcherException.php
similarity index 100%
rename from src/Loop/InvalidWatcherException.php
rename to lib/Loop/InvalidWatcherException.php
diff --git a/src/Loop/UnsupportedFeatureException.php b/lib/Loop/UnsupportedFeatureException.php
similarity index 100%
rename from src/Loop/UnsupportedFeatureException.php
rename to lib/Loop/UnsupportedFeatureException.php
diff --git a/lib/LoopFactory.php b/lib/LoopFactory.php
new file mode 100644
index 0000000..ea09f23
--- /dev/null
+++ b/lib/LoopFactory.php
@@ -0,0 +1,29 @@
+<?php
+
+namespace Amp\Loop;
+
+use AsyncInterop\Loop\DriverFactory;
+
+/**
+ * Default loop factory for Amp.
+ */
+class LoopFactory implements DriverFactory {
+    /**
+     * {@inheritdoc}
+     */
+    public function create() {
+        if (UvLoop::supported()) {
+            return new UvLoop;
+        }
+
+        if (EvLoop::supported()) {
+            return new EvLoop;
+        }
+
+        if (EventLoop::supported()) {
+            return new EventLoop;
+        }
+
+        return new NativeLoop;
+    }
+}
diff --git a/lib/NativeLoop.php b/lib/NativeLoop.php
new file mode 100644
index 0000000..78ebeed
--- /dev/null
+++ b/lib/NativeLoop.php
@@ -0,0 +1,283 @@
+<?php
+
+namespace Amp\Loop;
+
+use Amp\Loop\Internal\Watcher;
+use AsyncInterop\Loop\UnsupportedFeatureException;
+
+class NativeLoop extends Loop {
+    /** @var resource[] */
+    private $readStreams = [];
+
+    /** @var \Amp\Loop\Internal\Watcher[][] */
+    private $readWatchers = [];
+
+    /** @var resource[] */
+    private $writeStreams = [];
+
+    /** @var \Amp\Loop\Internal\Watcher[][] */
+    private $writeWatchers = [];
+
+    /** @var int[] */
+    private $timerExpires = [];
+
+    /** @var \SplPriorityQueue */
+    private $timerQueue;
+
+    /** @var \Amp\Loop\Internal\Watcher[][] */
+    private $signalWatchers = [];
+
+    /** @var bool */
+    private $signalHandling;
+
+    public function __construct() {
+        $this->timerQueue = new \SplPriorityQueue();
+        $this->signalHandling = \extension_loaded("pcntl");
+    }
+
+    protected function dispatch($blocking) {
+        $this->selectStreams(
+            $this->readStreams,
+            $this->writeStreams,
+            $blocking ? $this->getTimeout() : 0
+        );
+
+        if (!empty($this->timerExpires)) {
+            $time = (int) (\microtime(true) * self::MILLISEC_PER_SEC);
+
+            while (!$this->timerQueue->isEmpty()) {
+                list($watcher, $expiration) = $this->timerQueue->top();
+
+                $id = $watcher->id;
+
+                if (!isset($this->timerExpires[$id]) || $expiration !== $this->timerExpires[$id]) {
+                    $this->timerQueue->extract(); // Timer was removed from queue.
+                    continue;
+                }
+
+                if ($this->timerExpires[$id] > $time) { // Timer at top of queue has not expired.
+                    break;
+                }
+
+                $this->timerQueue->extract();
+
+                if ($watcher->type & Watcher::REPEAT) {
+                    $this->activate([$watcher]);
+                } else {
+                    $this->cancel($id);
+                }
+
+                // Execute the timer.
+                $callback = $watcher->callback;
+                $callback($id, $watcher->data);
+            }
+        }
+
+        if ($this->signalHandling) {
+            \pcntl_signal_dispatch();
+        }
+    }
+
+    /**
+     * @param resource[] $read
+     * @param resource[] $write
+     * @param int $timeout
+     */
+    private function selectStreams(array $read, array $write, $timeout) {
+        $timeout /= self::MILLISEC_PER_SEC;
+
+        if (!empty($read) || !empty($write)) { // Use stream_select() if there are any streams in the loop.
+            if ($timeout >= 0) {
+                $seconds = (int) $timeout;
+                $microseconds = (int) (($timeout - $seconds) * self::MICROSEC_PER_SEC);
+            } else {
+                $seconds = null;
+                $microseconds = null;
+            }
+
+            $except = null;
+
+            // Error reporting suppressed since stream_select() emits an E_WARNING if it is interrupted by a signal.
+            $count = @\stream_select($read, $write, $except, $seconds, $microseconds);
+
+            if ($count) {
+                foreach ($read as $stream) {
+                    $streamId = (int) $stream;
+                    if (isset($this->readWatchers[$streamId])) {
+                        foreach ($this->readWatchers[$streamId] as $watcher) {
+                            if (!isset($this->readWatchers[$streamId][$watcher->id])) {
+                                continue; // Watcher disabled by another IO watcher.
+                            }
+
+                            $callback = $watcher->callback;
+                            $callback($watcher->id, $stream, $watcher->data);
+                        }
+                    }
+                }
+
+                foreach ($write as $stream) {
+                    $streamId = (int) $stream;
+                    if (isset($this->writeWatchers[$streamId])) {
+                        foreach ($this->writeWatchers[$streamId] as $watcher) {
+                            if (!isset($this->writeWatchers[$streamId][$watcher->id])) {
+                                continue; // Watcher disabled by another IO watcher.
+                            }
+
+                            $callback = $watcher->callback;
+                            $callback($watcher->id, $stream, $watcher->data);
+                        }
+                    }
+                }
+            }
+
+            return;
+        }
+
+        if ($timeout > 0) { // Otherwise sleep with usleep() if $timeout > 0.
+            \usleep($timeout * self::MICROSEC_PER_SEC);
+        }
+    }
+
+    /**
+     * @return int Milliseconds until next timer expires or -1 if there are no pending times.
+     */
+    private function getTimeout() {
+        while (!$this->timerQueue->isEmpty()) {
+            list($watcher, $expiration) = $this->timerQueue->top();
+
+            $id = $watcher->id;
+
+            if (!isset($this->timerExpires[$id]) || $expiration !== $this->timerExpires[$id]) {
+                $this->timerQueue->extract(); // Timer was removed from queue.
+                continue;
+            }
+
+            $expiration -= (int) (\microtime(true) * self::MILLISEC_PER_SEC);
+
+            if ($expiration < 0) {
+                return 0;
+            }
+
+            return $expiration;
+        }
+
+        return -1;
+    }
+
+    /**
+     * {@inheritdoc}
+     *
+     * @throws \AsyncInterop\Loop\UnsupportedFeatureException If the pcntl extension is not available.
+     * @throws \RuntimeException If creating the backend signal handler fails.
+     */
+    public function onSignal($signo, callable $callback, $data = null) {
+        if (!$this->signalHandling) {
+            throw new UnsupportedFeatureException("Signal handling requires the pcntl extension");
+        }
+
+        return parent::onSignal($signo, $callback, $data);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function activate(array $watchers) {
+        foreach ($watchers as $watcher) {
+            switch ($watcher->type) {
+                case Watcher::READABLE:
+                    $streamId = (int) $watcher->value;
+                    $this->readWatchers[$streamId][$watcher->id] = $watcher;
+                    $this->readStreams[$streamId] = $watcher->value;
+                    break;
+
+                case Watcher::WRITABLE:
+                    $streamId = (int) $watcher->value;
+                    $this->writeWatchers[$streamId][$watcher->id] = $watcher;
+                    $this->writeStreams[$streamId] = $watcher->value;
+                    break;
+
+                case Watcher::DELAY:
+                case Watcher::REPEAT:
+                    $expiration = (int) (\microtime(true) * self::MILLISEC_PER_SEC) + $watcher->value;
+                    $this->timerExpires[$watcher->id] = $expiration;
+                    $this->timerQueue->insert([$watcher, $expiration], -$expiration);
+                    break;
+
+                case Watcher::SIGNAL:
+                    if (!isset($this->signalWatchers[$watcher->value])) {
+                        if (!@\pcntl_signal($watcher->value, [$this, 'handleSignal'])) {
+                            throw new \RuntimeException("Failed to register signal handler");
+                        }
+                    }
+
+                    $this->signalWatchers[$watcher->value][$watcher->id] = $watcher;
+                    break;
+
+                default:
+                    throw new \DomainException("Unknown watcher type");
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function deactivate(Watcher $watcher) {
+        switch ($watcher->type) {
+            case Watcher::READABLE:
+                $streamId = (int) $watcher->value;
+                unset($this->readWatchers[$streamId][$watcher->id]);
+                if (empty($this->readWatchers[$streamId])) {
+                    unset($this->readWatchers[$streamId], $this->readStreams[$streamId]);
+                }
+                break;
+
+            case Watcher::WRITABLE:
+                $streamId = (int) $watcher->value;
+                unset($this->writeWatchers[$streamId][$watcher->id]);
+                if (empty($this->writeWatchers[$streamId])) {
+                    unset($this->writeWatchers[$streamId], $this->writeStreams[$streamId]);
+                }
+                break;
+
+            case Watcher::DELAY:
+            case Watcher::REPEAT:
+                unset($this->timerExpires[$watcher->id]);
+                break;
+
+            case Watcher::SIGNAL:
+                if (isset($this->signalWatchers[$watcher->value])) {
+                    unset($this->signalWatchers[$watcher->value][$watcher->id]);
+
+                    if (empty($this->signalWatchers[$watcher->value])) {
+                        unset($this->signalWatchers[$watcher->value]);
+                        @\pcntl_signal($watcher->value, \SIG_DFL);
+                    }
+                }
+                break;
+
+            default: throw new \DomainException("Unknown watcher type");
+        }
+    }
+
+    /**
+     * @param int $signo
+     */
+    private function handleSignal($signo) {
+        foreach ($this->signalWatchers[$signo] as $watcher) {
+            if (!isset($this->signalWatchers[$signo][$watcher->id])) {
+                continue;
+            }
+
+            $callback = $watcher->callback;
+            $callback($watcher->id, $signo, $watcher->data);
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getHandle() {
+        return null;
+    }
+}
diff --git a/lib/UvLoop.php b/lib/UvLoop.php
new file mode 100644
index 0000000..febe673
--- /dev/null
+++ b/lib/UvLoop.php
@@ -0,0 +1,255 @@
+<?php
+
+namespace Amp\Loop;
+
+use Amp\Loop\Internal\Watcher;
+
+class UvLoop extends Loop {
+    /** @var resource A uv_loop resource created with uv_loop_new() */
+    private $handle;
+
+    /** @var resource[] */
+    private $events = [];
+
+    /** @var \Amp\Loop\Internal\Watcher[]|\Amp\Loop\Internal\Watcher[][] */
+    private $watchers = [];
+
+    /** @var resource[] */
+    private $read = [];
+
+    /** @var resource[] */
+    private $write = [];
+
+    /** @var callable */
+    private $ioCallback;
+
+    /** @var callable */
+    private $timerCallback;
+
+    /** @var callable */
+    private $signalCallback;
+
+    public static function supported() {
+        return \extension_loaded("uv");
+    }
+
+    public function __construct() {
+        $this->handle = \uv_loop_new();
+
+        $this->ioCallback = function ($event, $status, $events, $resource) {
+            switch ($status) {
+                case 0: // OK
+                    break;
+
+                // If $status is a severe error, stop the poll and throw an exception.
+                case \UV::EACCES:
+                case \UV::EBADF:
+                case \UV::EINVAL:
+                case \UV::ENOTSOCK:
+                    throw new \RuntimeException(
+                        \sprintf("UV_%s: %s", \uv_err_name($status), \ucfirst(\uv_strerror($status)))
+                    );
+
+                default: // Ignore other (probably) trivial warnings and continuing polling.
+                    return;
+            }
+
+            $watchers = $this->watchers[(int) $event];
+
+            foreach ($watchers as $watcher) {
+                $callback = $watcher->callback;
+                $callback($watcher->id, $resource, $watcher->data);
+            }
+        };
+
+        $this->timerCallback = function ($event) {
+            $watcher = $this->watchers[(int) $event];
+
+            if ($watcher->type & Watcher::DELAY) {
+                $this->cancel($watcher->id);
+            }
+
+            $callback = $watcher->callback;
+            $callback($watcher->id, $watcher->data);
+        };
+
+        $this->signalCallback = function ($event, $signo) {
+            $watcher = $this->watchers[(int) $event];
+
+            $callback = $watcher->callback;
+            $callback($watcher->id, $signo, $watcher->data);
+        };
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function dispatch($blocking) {
+        \uv_run($this->handle, $blocking ? \UV::RUN_ONCE : \UV::RUN_NOWAIT);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function activate(array $watchers) {
+        foreach ($watchers as $watcher) {
+            $id = $watcher->id;
+
+            switch ($watcher->type) {
+                case Watcher::READABLE:
+                    $streamId = (int) $watcher->value;
+
+                    if (isset($this->read[$streamId])) {
+                        $event = $this->read[$streamId];
+                    } elseif (isset($this->events[$id])) {
+                        $event = $this->read[$streamId] = $this->events[$id];
+                    } else {
+                        $event = $this->read[$streamId] = \uv_poll_init_socket($this->handle, $watcher->value);
+                    }
+
+                    $this->events[$id] = $event;
+                    $this->watchers[(int) $event][$id] = $watcher;
+
+                    if (!\uv_is_active($event)) {
+                        \uv_poll_start($event, \UV::READABLE, $this->ioCallback);
+                    }
+                    break;
+
+                case Watcher::WRITABLE:
+                    $streamId = (int) $watcher->value;
+
+                    if (isset($this->write[$streamId])) {
+                        $event = $this->write[$streamId];
+                    } elseif (isset($this->events[$id])) {
+                        $event = $this->write[$streamId] = $this->events[$id];
+                    } else {
+                        $event = $this->write[$streamId] = \uv_poll_init_socket($this->handle, $watcher->value);
+                    }
+
+                    $this->events[$id] = $event;
+                    $this->watchers[(int) $event][$id] = $watcher;
+
+
+                    if (!\uv_is_active($event)) {
+                        \uv_poll_start($event, \UV::WRITABLE, $this->ioCallback);
+                    }
+                    break;
+
+                case Watcher::DELAY:
+                case Watcher::REPEAT:
+                    if (isset($this->events[$id])) {
+                        $event = $this->events[$id];
+                    } else {
+                        $event = $this->events[$id] = \uv_timer_init($this->handle);
+                    }
+
+                    $this->watchers[(int) $event] = $watcher;
+
+                    \uv_timer_start(
+                        $event,
+                        $watcher->value,
+                        $watcher->type & Watcher::REPEAT ? $watcher->value : 0,
+                        $this->timerCallback
+                    );
+                    break;
+
+                case Watcher::SIGNAL:
+                    if (isset($this->events[$id])) {
+                        $event = $this->events[$id];
+                    } else {
+                        $event = $this->events[$id] = \uv_signal_init($this->handle);
+                    }
+
+                    $this->watchers[(int) $event] = $watcher;
+
+                    \uv_signal_start($event, $this->signalCallback, $watcher->value);
+                    break;
+
+                default: throw new \DomainException("Unknown watcher type");
+            }
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    protected function deactivate(Watcher $watcher) {
+        $id = $watcher->id;
+
+        if (!isset($this->events[$id])) {
+            return;
+        }
+
+        $event = $this->events[$id];
+        $eventId = (int) $event;
+
+        switch ($watcher->type) {
+            case Watcher::READABLE:
+                unset($this->watchers[$eventId][$id]);
+
+                if (empty($this->watchers[$eventId])) {
+                    unset($this->watchers[$eventId]);
+                    unset($this->read[(int) $watcher->value]);
+                    if (\uv_is_active($event)) {
+                        \uv_poll_stop($event);
+                    }
+                }
+                break;
+
+            case Watcher::WRITABLE:
+                unset($this->watchers[$eventId][$id]);
+
+                if (empty($this->watchers[$eventId])) {
+                    unset($this->watchers[$eventId]);
+                    unset($this->write[(int) $watcher->value]);
+                    if (\uv_is_active($event)) {
+                        \uv_poll_stop($event);
+                    }
+                }
+                break;
+
+            case Watcher::DELAY:
+            case Watcher::REPEAT:
+                unset($this->watchers[$eventId]);
+                if (\uv_is_active($event)) {
+                    \uv_timer_stop($event);
+                }
+                break;
+
+            case Watcher::SIGNAL:
+                unset($this->watchers[$eventId]);
+                if (\uv_is_active($event)) {
+                    \uv_signal_stop($event);
+                }
+                break;
+
+            default: throw new \DomainException("Unknown watcher type");
+        }
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function cancel($watcherIdentifier) {
+        parent::cancel($watcherIdentifier);
+
+        if (!isset($this->events[$watcherIdentifier])) {
+            return;
+        }
+
+        $event = $this->events[$watcherIdentifier];
+
+        if (empty($this->watchers[(int) $event])) {
+            \uv_close($event);
+        }
+
+        unset($this->events[$watcherIdentifier]);
+    }
+
+    /**
+     * {@inheritdoc}
+     */
+    public function getHandle() {
+        return $this->handle;
+    }
+}
diff --git a/phpunit.xml b/phpunit.xml
deleted file mode 100644
index b2dbf88..0000000
--- a/phpunit.xml
+++ /dev/null
@@ -1,12 +0,0 @@
-<phpunit bootstrap="./vendor/autoload.php" colors="true">
-    <testsuites>
-        <testsuite name="Tests">
-            <directory>./test</directory>
-        </testsuite>
-    </testsuites>
-    <filter>
-        <whitelist addUncoveredFilesFromWhitelist="true">
-            <directory>./src</directory>
-        </whitelist>
-    </filter>
-</phpunit>
diff --git a/phpunit.xml.dist b/phpunit.xml.dist
index 9ef7f5a..8e29216 100644
--- a/phpunit.xml.dist
+++ b/phpunit.xml.dist
@@ -1,21 +1,24 @@
 <?xml version="1.0" encoding="UTF-8"?>
 <phpunit
-    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
-    xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/4.1/phpunit.xsd"
-    backupGlobals="false"
-    backupStaticAttributes="false"
-    bootstrap="vendor/autoload.php"
-    colors="true"
-    convertErrorsToExceptions="true"
-    convertNoticesToExceptions="true"
-    convertWarningsToExceptions="true"
-    processIsolation="false"
-    stopOnFailure="false"
+        xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+        xsi:noNamespaceSchemaLocation="http://schema.phpunit.de/4.1/phpunit.xsd"
+        backupGlobals="false"
+        backupStaticAttributes="false"
+        bootstrap="vendor/autoload.php"
+        colors="true"
+        convertErrorsToExceptions="true"
+        convertNoticesToExceptions="true"
+        convertWarningsToExceptions="true"
+        processIsolation="false"
+        stopOnFailure="false"
 >
     <testsuites>
         <testsuite name="Amp">
             <directory>test</directory>
         </testsuite>
+        <testsuite name="Amp Loop PHPT">
+            <directory suffix=".phpt">test/phpt</directory>
+        </testsuite>
     </testsuites>
     <filter>
         <whitelist>
@@ -24,5 +27,6 @@
     </filter>
     <logging>
         <log type="coverage-html" target="build/coverage" title="Amp" highlight="true"/>
+        <log type="coverage-clover" target="build/logs/clover.xml"/>
     </logging>
-</phpunit>
\ No newline at end of file
+</phpunit>
diff --git a/test/EvLoopTest.php b/test/EvLoopTest.php
new file mode 100644
index 0000000..2ec7716
--- /dev/null
+++ b/test/EvLoopTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Amp\Test\Loop;
+
+use Amp\Loop\EvLoop;
+use AsyncInterop\Loop\DriverFactory;
+use AsyncInterop\Loop\Test;
+
+/**
+ * @requires extension ev
+ */
+class EvLoopTest extends Test {
+    public function getFactory() {
+        $factory = $this->getMockBuilder(DriverFactory::class)->getMock();
+
+        $factory->method('create')
+            ->willReturn(new EvLoop);
+
+        return $factory;
+    }
+}
diff --git a/test/EventLoopTest.php b/test/EventLoopTest.php
new file mode 100644
index 0000000..db6da7b
--- /dev/null
+++ b/test/EventLoopTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Amp\Test\Loop;
+
+use Amp\Loop\EventLoop;
+use AsyncInterop\Loop\DriverFactory;
+use AsyncInterop\Loop\Test;
+
+/**
+ * @requires extension event
+ */
+class EventLoopTest extends Test {
+    public function getFactory() {
+        $factory = $this->getMockBuilder(DriverFactory::class)->getMock();
+
+        $factory->method('create')
+            ->willReturn(new EventLoop);
+
+        return $factory;
+    }
+}
diff --git a/test/NativeLoopTest.php b/test/NativeLoopTest.php
new file mode 100644
index 0000000..78dd958
--- /dev/null
+++ b/test/NativeLoopTest.php
@@ -0,0 +1,18 @@
+<?php
+
+namespace Amp\Test\Loop;
+
+use Amp\Loop\NativeLoop;
+use AsyncInterop\Loop\DriverFactory;
+use AsyncInterop\Loop\Test;
+
+class NativeLoopTest extends Test {
+    public function getFactory() {
+        $factory = $this->getMockBuilder(DriverFactory::class)->getMock();
+
+        $factory->method('create')
+            ->willReturn(new NativeLoop());
+
+        return $factory;
+    }
+}
diff --git a/test/UvLoopTest.php b/test/UvLoopTest.php
new file mode 100644
index 0000000..fecb785
--- /dev/null
+++ b/test/UvLoopTest.php
@@ -0,0 +1,21 @@
+<?php
+
+namespace Amp\Test\Loop;
+
+use Amp\Loop\UvLoop;
+use AsyncInterop\Loop\DriverFactory;
+use AsyncInterop\Loop\Test;
+
+/**
+ * @requires extension uv
+ */
+class UvLoopTest extends Test {
+    public function getFactory() {
+        $factory = $this->getMockBuilder(DriverFactory::class)->getMock();
+
+        $factory->method('create')
+            ->willReturn(new UvLoop);
+
+        return $factory;
+    }
+}