diff --git a/extra/CHANGES.txt b/extra/CHANGES.txt
index 6aa74bf9924..ffd5659ad0f 100644
--- a/extra/CHANGES.txt
+++ b/extra/CHANGES.txt
@@ -56,6 +56,8 @@
 	all : [std] allow setting haxe.Exception.stack (#12213)
 	all : [std] Serializer: implement reset method (#12068)
 	all : [std] use Vectors in haxe.zip (#11034)
+	all : [std] add haxe.IHandle interface (#12766)
+	all : [std] add haxe.GcFinalizer with handle-based API (#12766)
 	all : [messageReparting] pretty errors as default message reporting (#11587)
 	all : [messageReporting] add config to use absolute positions (#11439)
 	all : [display] diagnostics as json rpc (#11412)
diff --git a/std/cpp/_std/haxe/GcFinalizer.hx b/std/cpp/_std/haxe/GcFinalizer.hx
new file mode 100644
index 00000000000..06914a300c8
--- /dev/null
+++ b/std/cpp/_std/haxe/GcFinalizer.hx
@@ -0,0 +1,91 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+import haxe.atomic.AtomicBool;
+
+private class Registration<T> {
+	public var heldValue:Null<T>;
+	public var callback:Null<T->Void>;
+	public var cancelled:AtomicBool;
+	public var weakTarget:cpp.vm.WeakRef<Dynamic>;
+
+	public function new(target:Dynamic, heldValue:T, callback:T->Void) {
+		this.weakTarget = new cpp.vm.WeakRef<Dynamic>(target);
+		this.heldValue = heldValue;
+		this.callback = callback;
+		this.cancelled = new AtomicBool(false);
+	}
+}
+
+private class Handle<T> implements IHandle {
+	var reg:Registration<T>;
+
+	public function new(reg:Registration<T>) {
+		this.reg = reg;
+	}
+
+	public function close():Void {
+		if (reg.cancelled.compareExchange(false, true) == false) {
+			reg.callback = null;
+			reg.heldValue = null;
+		}
+	}
+}
+
+@:coreApi
+class GcFinalizer<T> {
+	var callback:T->Void;
+	var registrations:Array<Registration<T>>;
+
+	public function new(callback:T->Void) {
+		this.callback = callback;
+		this.registrations = [];
+	}
+
+	function pollQueue():Void {
+		var i = registrations.length - 1;
+		while (i >= 0) {
+			var reg = registrations[i];
+			if (reg.weakTarget.get() == null) {
+				if (reg.cancelled.compareExchange(false, true) == false) {
+					reg.callback(reg.heldValue);
+					reg.callback = null;
+					reg.heldValue = null;
+				}
+				registrations.splice(i, 1);
+			} else if (reg.cancelled.load()) {
+				// close() already nulled fields
+				registrations.splice(i, 1);
+			}
+			i--;
+		}
+	}
+
+	public function register(target:{}, heldValue:T):IHandle {
+		pollQueue();
+		var reg = new Registration(target, heldValue, callback);
+		registrations.push(reg);
+		return new Handle(reg);
+	}
+}
diff --git a/std/eval/_std/haxe/GcFinalizer.hx b/std/eval/_std/haxe/GcFinalizer.hx
new file mode 100644
index 00000000000..678a2385f48
--- /dev/null
+++ b/std/eval/_std/haxe/GcFinalizer.hx
@@ -0,0 +1,74 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+import haxe.atomic.AtomicBool;
+
+private class Registration<T> {
+	public var heldValue:Null<T>;
+	public var cancelled:AtomicBool;
+	public var callback:Null<T->Void>;
+
+	public function new(heldValue:T, callback:T->Void) {
+		this.heldValue = heldValue;
+		this.cancelled = new AtomicBool(false);
+		this.callback = callback;
+	}
+}
+
+private class Handle<T> implements IHandle {
+	var reg:Registration<T>;
+
+	public function new(reg:Registration<T>) {
+		this.reg = reg;
+	}
+
+	public function close():Void {
+		if (reg.cancelled.compareExchange(false, true) == false) {
+			reg.callback = null;
+			reg.heldValue = null;
+		}
+	}
+}
+
+@:coreApi
+class GcFinalizer<T> {
+	var callback:T->Void;
+
+	public function new(callback:T->Void) {
+		this.callback = callback;
+	}
+
+	public function register(target:{}, heldValue:T):IHandle {
+		var reg = new Registration(heldValue, callback);
+		eval.vm.Gc.finalise(function(_) {
+			if (reg.cancelled.compareExchange(false, true) == false) {
+				reg.callback(reg.heldValue);
+				reg.callback = null;
+				reg.heldValue = null;
+			}
+		}, target);
+
+		return new Handle(reg);
+	}
+}
diff --git a/std/haxe/GcFinalizer.hx b/std/haxe/GcFinalizer.hx
new file mode 100644
index 00000000000..8f8bd5ded01
--- /dev/null
+++ b/std/haxe/GcFinalizer.hx
@@ -0,0 +1,55 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+/**
+	A GC finalizer registry that invokes a callback when a watched object
+	is garbage-collected. Modeled after JavaScript's `FinalizationRegistry`.
+
+	The callback receives a held value (not the collected object itself),
+	which is safe because the object may already be in an invalid state.
+
+	Not all targets support GC finalizers. On unsupported targets, the
+	constructor throws `NotImplementedException`.
+**/
+class GcFinalizer<T> {
+	/**
+		Creates a new `GcFinalizer` with the given cleanup `callback`.
+		The callback will be invoked with the held value when a registered
+		target object is garbage-collected.
+	**/
+	public function new(callback:T->Void) {
+		throw new haxe.exceptions.NotImplementedException("Not implemented for this platform");
+	}
+
+	/**
+		Registers `target` for clean-up. When `target` is garbage-collected,
+		the callback will be invoked with `heldValue`.
+
+		Returns an `IHandle` handle. Calling `close()` on the handle
+		cancels the registration, preventing the callback from firing.
+	**/
+	public function register(target:{}, heldValue:T):IHandle {
+		return null;
+	}
+}
diff --git a/std/haxe/IHandle.hx b/std/haxe/IHandle.hx
new file mode 100644
index 00000000000..240371e2f7d
--- /dev/null
+++ b/std/haxe/IHandle.hx
@@ -0,0 +1,33 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+/**
+	A general-purpose interface for handles that can be released
+	by calling `close()`. Used by `GcFinalizer` to return cancellation
+	handles, and intended for thread callback handles, coroutine
+	scheduler handles, and similar patterns.
+**/
+interface IHandle {
+	function close():Void;
+}
diff --git a/std/js/_std/haxe/GcFinalizer.hx b/std/js/_std/haxe/GcFinalizer.hx
new file mode 100644
index 00000000000..c8548d46c1f
--- /dev/null
+++ b/std/js/_std/haxe/GcFinalizer.hx
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+@:coreApi
+class GcFinalizer<T> {
+	var h:js.lib.FinalizationRegistry<T>;
+
+	public inline function new(callback:T->Void) {
+		h = new js.lib.FinalizationRegistry(callback);
+	}
+
+	public inline function register(target:{}, heldValue:T):IHandle {
+		var token = {};
+		h.register(target, heldValue, token);
+		return cast {close: function() h.unregister(token)};
+	}
+}
diff --git a/std/js/lib/FinalizationRegistry.hx b/std/js/lib/FinalizationRegistry.hx
new file mode 100644
index 00000000000..a822dbefb6c
--- /dev/null
+++ b/std/js/lib/FinalizationRegistry.hx
@@ -0,0 +1,49 @@
+package js.lib;
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+/**
+	A `FinalizationRegistry` object lets you request a callback when a value is garbage-collected.
+
+	Documentation [FinalizationRegistry](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/FinalizationRegistry) by
+	[Mozilla Contributors](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/FinalizationRegistry/contributors.txt),
+	licensed under [CC-BY-SA 2.5](https://creativecommons.org/licenses/by-sa/2.5/).
+**/
+@:native("FinalizationRegistry")
+extern class FinalizationRegistry<T> {
+	/**
+		Creates a new `FinalizationRegistry` with the given cleanup callback.
+	**/
+	function new(cleanupCallback:T->Void);
+
+	/**
+		Registers a target object with the registry, associating it with a held value
+		and an optional unregister token.
+	**/
+	function register(target:{}, heldValue:T, ?unregisterToken:{}):Void;
+
+	/**
+		Unregisters any registrations associated with the given unregister token.
+		Returns `true` if at least one registration was removed.
+	**/
+	function unregister(unregisterToken:{}):Bool;
+}
diff --git a/std/jvm/_std/haxe/GcFinalizer.hx b/std/jvm/_std/haxe/GcFinalizer.hx
new file mode 100644
index 00000000000..1eee0f7d9fa
--- /dev/null
+++ b/std/jvm/_std/haxe/GcFinalizer.hx
@@ -0,0 +1,89 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+import haxe.atomic.AtomicBool;
+import java.lang.ref.WeakReference;
+import java.lang.ref.ReferenceQueue;
+
+private class Registration<T> extends WeakReference<Dynamic> {
+	public var heldValue:Null<T>;
+	public var callback:Null<T->Void>;
+	public var cancelled:AtomicBool;
+
+	public function new(target:Dynamic, heldValue:T, callback:T->Void, queue:ReferenceQueue<Dynamic>) {
+		super(target, queue);
+		this.heldValue = heldValue;
+		this.callback = callback;
+		this.cancelled = new AtomicBool(false);
+	}
+}
+
+private class Handle<T> implements IHandle {
+	var reg:Registration<T>;
+
+	public function new(reg:Registration<T>) {
+		this.reg = reg;
+	}
+
+	public function close():Void {
+		if (reg.cancelled.compareExchange(false, true) == false) {
+			reg.callback = null;
+			reg.heldValue = null;
+		}
+	}
+}
+
+@:coreApi
+class GcFinalizer<T> {
+	var callback:T->Void;
+	var queue:ReferenceQueue<Dynamic>;
+	var allRegs:Array<Registration<T>>;
+
+	public function new(callback:T->Void) {
+		this.callback = callback;
+		this.queue = new ReferenceQueue();
+		this.allRegs = [];
+	}
+
+	function pollQueue():Void {
+		var ref:Dynamic = null;
+		while ((ref = queue.poll()) != null) {
+			var reg:Registration<T> = cast ref;
+			if (reg.cancelled.compareExchange(false, true) == false) {
+				reg.callback(reg.heldValue);
+				reg.callback = null;
+				reg.heldValue = null;
+			}
+			allRegs.remove(reg);
+		}
+	}
+
+	public function register(target:{}, heldValue:T):IHandle {
+		pollQueue();
+		var reg = new Registration(target, heldValue, callback, queue);
+		allRegs.push(reg);
+
+		return new Handle(reg);
+	}
+}
diff --git a/std/lua/_std/haxe/GcFinalizer.hx b/std/lua/_std/haxe/GcFinalizer.hx
new file mode 100644
index 00000000000..11aaf3aac64
--- /dev/null
+++ b/std/lua/_std/haxe/GcFinalizer.hx
@@ -0,0 +1,47 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+@:coreApi
+class GcFinalizer<T> {
+	var callback:T->Void;
+	var nextId:Int;
+
+	public function new(callback:T->Void) {
+		this.callback = callback;
+		this.nextId = 0;
+	}
+
+	public function register(target:{}, heldValue:T):IHandle {
+		var cb = callback;
+		var id = nextId++;
+		var proxy:Dynamic = lua.Syntax.code(
+			"setmetatable({held = {0}, cb = {1}}, {__gc = function(self) if self.cb then self.cb(self.held) end end})",
+			heldValue, cb);
+		lua.Syntax.code("rawset({0}, '__hx_gc_' .. {1}, {2})", target, id, proxy);
+
+		return cast {
+			close: function() lua.Syntax.code("{0}.cb = nil", proxy)
+		};
+	}
+}
diff --git a/std/python/_std/haxe/GcFinalizer.hx b/std/python/_std/haxe/GcFinalizer.hx
new file mode 100644
index 00000000000..dbed3b271d7
--- /dev/null
+++ b/std/python/_std/haxe/GcFinalizer.hx
@@ -0,0 +1,39 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package haxe;
+
+import python.lib.Weakref.PythonFinalizer;
+
+@:coreApi
+class GcFinalizer<T> {
+	var callback:T->Void;
+
+	public function new(callback:T->Void) {
+		this.callback = callback;
+	}
+
+	public function register(target:{}, heldValue:T):IHandle {
+		var fin = new PythonFinalizer(target, callback, heldValue);
+		return cast {close: function() fin.detach()};
+	}
+}
diff --git a/std/python/lib/Weakref.hx b/std/python/lib/Weakref.hx
new file mode 100644
index 00000000000..7f620a33fb2
--- /dev/null
+++ b/std/python/lib/Weakref.hx
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C)2005-2019 Haxe Foundation
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the "Software"),
+ * to deal in the Software without restriction, including without limitation
+ * the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ * and/or sell copies of the Software, and to permit persons to whom the
+ * Software is furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in
+ * all copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
+ * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
+ * DEALINGS IN THE SOFTWARE.
+ */
+
+package python.lib;
+
+@:pythonImport("weakref")
+extern class Weakref {
+	static function ref<T:{}>(object:T):WeakrefCallable<T>;
+}
+
+extern class WeakrefCallable<T:{}> {
+	@:selfCall function call():Null<T>;
+}
+
+@:pythonImport("weakref", "finalize")
+extern class PythonFinalizer {
+	function new(obj:{}, func:Dynamic, held:Dynamic);
+	function detach():Bool;
+}
diff --git a/tests/unit/src/unit/TestGcFinalizer.hx b/tests/unit/src/unit/TestGcFinalizer.hx
new file mode 100644
index 00000000000..d97c7c007a0
--- /dev/null
+++ b/tests/unit/src/unit/TestGcFinalizer.hx
@@ -0,0 +1,79 @@
+package unit;
+
+class TestGcFinalizer extends Test {
+	function testConstructNoThrow() {
+		#if (js || python || eval || lua || jvm || cpp)
+		var finalizer = new haxe.GcFinalizer(function(v:String) {});
+		t(finalizer != null);
+		#else
+		noAssert();
+		#end
+	}
+
+	function testRegisterNoThrow() {
+		#if (js || python || eval || lua || jvm || cpp)
+		var finalizer = new haxe.GcFinalizer(function(v:String) {});
+		var target = {id: 1};
+		var handle = finalizer.register(target, "hello");
+		t(handle != null);
+		#else
+		noAssert();
+		#end
+	}
+
+	function testCloseNoThrow() {
+		#if (js || python || eval || lua || jvm || cpp)
+		var finalizer = new haxe.GcFinalizer(function(v:String) {});
+		var target = {id: 1};
+		var handle = finalizer.register(target, "hello");
+		handle.close();
+		t(true);
+		#else
+		noAssert();
+		#end
+	}
+
+	function testUnsupportedTargetThrows() {
+		#if !(js || python || eval || lua || jvm || cpp)
+		exc(function() new haxe.GcFinalizer(function(v:String) {}));
+		#else
+		noAssert();
+		#end
+	}
+
+	function testCallbackFiresAfterGc() {
+		#if eval
+		var called = false;
+		var heldResult:Null<String> = null;
+		var finalizer = new haxe.GcFinalizer(function(v:String) {
+			called = true;
+			heldResult = v;
+		});
+		finalizer.register({id: 1}, "collected");
+		// Force GC
+		eval.vm.Gc.full_major();
+		eval.vm.Gc.full_major();
+		t(called);
+		eq(heldResult, "collected");
+		#else
+		noAssert();
+		#end
+	}
+
+	function testClosePreventsCallback() {
+		#if eval
+		var called = false;
+		var finalizer = new haxe.GcFinalizer(function(v:String) {
+			called = true;
+		});
+		var handle = finalizer.register({id: 1}, "collected");
+		handle.close();
+		// Force GC
+		eval.vm.Gc.full_major();
+		eval.vm.Gc.full_major();
+		f(called);
+		#else
+		noAssert();
+		#end
+	}
+}
diff --git a/tests/unit/src/unit/TestMain.hx b/tests/unit/src/unit/TestMain.hx
index 8cc773e8283..fb10ca054d9 100644
--- a/tests/unit/src/unit/TestMain.hx
+++ b/tests/unit/src/unit/TestMain.hx
@@ -99,6 +99,7 @@ function main() {
 		#end
 		new TestMapComprehension(),
 		new TestMacro(),
+		new TestGcFinalizer(),
 		new TestKeyValueIterator(),
 		new TestFieldVariance(),
 		new TestConstrainedMonomorphs(),