diff --git a/scripts/fiber/tests-passing.txt b/scripts/fiber/tests-passing.txt
index c56a44b5b2..c749ed37ab 100644
--- a/scripts/fiber/tests-passing.txt
+++ b/scripts/fiber/tests-passing.txt
@@ -1207,6 +1207,7 @@ src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js
 * can opt-in to deferred/animation scheduling inside componentDidMount/Update
 * performs Task work even after time runs out
 * does not perform animation work after time runs out
+* can force synchronous updates with syncUpdates, even inside batchedUpdates
 
 src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
 * can update child nodes of a host instance
@@ -1576,6 +1577,7 @@ src/renderers/shared/shared/__tests__/ReactUpdates-test.js
 * unstable_batchedUpdates should return value from a callback
 * unmounts and remounts a root in the same batch
 * handles reentrant mounting in synchronous mode
+* mounts and unmounts are sync even in a batch
 
 src/renderers/shared/shared/__tests__/refs-destruction-test.js
 * should remove refs when destroying the parent
diff --git a/src/renderers/dom/fiber/ReactDOMFiber.js b/src/renderers/dom/fiber/ReactDOMFiber.js
index a4ed6d3e54..26c3734909 100644
--- a/src/renderers/dom/fiber/ReactDOMFiber.js
+++ b/src/renderers/dom/fiber/ReactDOMFiber.js
@@ -67,9 +67,10 @@ type HostContextDev = {
 };
 type HostContextProd = string;
 type HostContext = HostContextDev | HostContextProd;
-
-let eventsEnabled : ?boolean = null;
-let selectionInformation : ?mixed = null;
+type CommitInfo = {
+  eventsEnabled: boolean,
+  selectionInformation: mixed,
+};
 
 var ELEMENT_NODE_TYPE = 1;
 var DOC_NODE_TYPE = 9;
@@ -137,17 +138,18 @@ var DOMRenderer = ReactFiberReconciler({
     return getChildNamespace(parentNamespace, type);
   },
 
-  prepareForCommit() : void {
-    eventsEnabled = ReactBrowserEventEmitter.isEnabled();
+  prepareForCommit() : CommitInfo {
+    const eventsEnabled = ReactBrowserEventEmitter.isEnabled();
     ReactBrowserEventEmitter.setEnabled(false);
-    selectionInformation = ReactInputSelection.getSelectionInformation();
+    return {
+      eventsEnabled,
+      selectionInformation: ReactInputSelection.getSelectionInformation(),
+    };
   },
 
-  resetAfterCommit() : void {
-    ReactInputSelection.restoreSelection(selectionInformation);
-    selectionInformation = null;
-    ReactBrowserEventEmitter.setEnabled(eventsEnabled);
-    eventsEnabled = null;
+  resetAfterCommit(commitInfo : CommitInfo) : void {
+    ReactInputSelection.restoreSelection(commitInfo.selectionInformation);
+    ReactBrowserEventEmitter.setEnabled(commitInfo.eventsEnabled);
   },
 
   createInstance(
diff --git a/src/renderers/shared/fiber/ReactFiberBeginWork.js b/src/renderers/shared/fiber/ReactFiberBeginWork.js
index 4cfb1f4bb1..e5ee7a831d 100644
--- a/src/renderers/shared/fiber/ReactFiberBeginWork.js
+++ b/src/renderers/shared/fiber/ReactFiberBeginWork.js
@@ -66,8 +66,8 @@ if (__DEV__) {
   var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
 }
 
-module.exports = function<T, P, I, TI, C, CX>(
-  config : HostConfig<T, P, I, TI, C, CX>,
+module.exports = function<T, P, I, TI, C, CX, CI>(
+  config : HostConfig<T, P, I, TI, C, CX, CI>,
   hostContext : HostContext<C, CX>,
   scheduleUpdate : (fiber : Fiber, priorityLevel : PriorityLevel) => void,
   getPriorityContext : () => PriorityLevel,
diff --git a/src/renderers/shared/fiber/ReactFiberCommitWork.js b/src/renderers/shared/fiber/ReactFiberCommitWork.js
index bb56a4c78f..429e892e0b 100644
--- a/src/renderers/shared/fiber/ReactFiberCommitWork.js
+++ b/src/renderers/shared/fiber/ReactFiberCommitWork.js
@@ -33,8 +33,8 @@ var {
   ContentReset,
 } = require('ReactTypeOfSideEffect');
 
-module.exports = function<T, P, I, TI, C, CX>(
-  config : HostConfig<T, P, I, TI, C, CX>,
+module.exports = function<T, P, I, TI, C, CX, CI>(
+  config : HostConfig<T, P, I, TI, C, CX, CI>,
   hostContext : HostContext<C, CX>,
   captureError : (failedFiber : Fiber, error: Error) => ?Fiber
 ) {
diff --git a/src/renderers/shared/fiber/ReactFiberCompleteWork.js b/src/renderers/shared/fiber/ReactFiberCompleteWork.js
index bffecb3c46..8c836cfda5 100644
--- a/src/renderers/shared/fiber/ReactFiberCompleteWork.js
+++ b/src/renderers/shared/fiber/ReactFiberCompleteWork.js
@@ -46,8 +46,8 @@ if (__DEV__) {
   var ReactDebugCurrentFiber = require('ReactDebugCurrentFiber');
 }
 
-module.exports = function<T, P, I, TI, C, CX>(
-  config : HostConfig<T, P, I, TI, C, CX>,
+module.exports = function<T, P, I, TI, C, CX, CI>(
+  config : HostConfig<T, P, I, TI, C, CX, CI>,
   hostContext : HostContext<C, CX>,
 ) {
   const {
diff --git a/src/renderers/shared/fiber/ReactFiberHostContext.js b/src/renderers/shared/fiber/ReactFiberHostContext.js
index 529271de6a..de311124ca 100644
--- a/src/renderers/shared/fiber/ReactFiberHostContext.js
+++ b/src/renderers/shared/fiber/ReactFiberHostContext.js
@@ -34,8 +34,8 @@ export type HostContext<C, CX> = {
   resetHostContainer() : void,
 };
 
-module.exports = function<T, P, I, TI, C, CX>(
-  config : HostConfig<T, P, I, TI, C, CX>
+module.exports = function<T, P, I, TI, C, CX, CI>(
+  config : HostConfig<T, P, I, TI, C, CX, CI>
 ) : HostContext<C, CX> {
   const {
     getChildHostContext,
diff --git a/src/renderers/shared/fiber/ReactFiberReconciler.js b/src/renderers/shared/fiber/ReactFiberReconciler.js
index ff55cbddaa..3424ef683f 100644
--- a/src/renderers/shared/fiber/ReactFiberReconciler.js
+++ b/src/renderers/shared/fiber/ReactFiberReconciler.js
@@ -43,7 +43,7 @@ export type Deadline = {
 
 type OpaqueNode = Fiber;
 
-export type HostConfig<T, P, I, TI, C, CX> = {
+export type HostConfig<T, P, I, TI, C, CX, CI> = {
 
   getRootHostContext(rootContainerInstance : C) : CX,
   getChildHostContext(parentHostContext : CX, type : T) : CX,
@@ -69,8 +69,8 @@ export type HostConfig<T, P, I, TI, C, CX> = {
   scheduleAnimationCallback(callback : () => void) : void,
   scheduleDeferredCallback(callback : (deadline : Deadline) => void) : void,
 
-  prepareForCommit() : void,
-  resetAfterCommit() : void,
+  prepareForCommit() : CI,
+  resetAfterCommit(commitInfo : CI) : void,
 
   useSyncScheduling ?: boolean,
 };
@@ -100,7 +100,7 @@ getContextForSubtree._injectFiber(function(fiber : Fiber) {
     parentContext;
 });
 
-module.exports = function<T, P, I, TI, C, CX>(config : HostConfig<T, P, I, TI, C, CX>) : Reconciler<C, I, TI> {
+module.exports = function<T, P, I, TI, C, CX, CI>(config : HostConfig<T, P, I, TI, C, CX, CI>) : Reconciler<C, I, TI> {
 
   var {
     scheduleUpdate,
diff --git a/src/renderers/shared/fiber/ReactFiberScheduler.js b/src/renderers/shared/fiber/ReactFiberScheduler.js
index e78d1c40ee..20603ec688 100644
--- a/src/renderers/shared/fiber/ReactFiberScheduler.js
+++ b/src/renderers/shared/fiber/ReactFiberScheduler.js
@@ -74,7 +74,7 @@ if (__DEV__) {
 
 var timeHeuristicForUnitOfWork = 1;
 
-module.exports = function<T, P, I, TI, C, CX>(config : HostConfig<T, P, I, TI, C, CX>) {
+module.exports = function<T, P, I, TI, C, CX, CI>(config : HostConfig<T, P, I, TI, C, CX, CI>) {
   const hostContext = ReactFiberHostContext(config);
   const { popHostContainer, popHostContext, resetHostContainer } = hostContext;
   const { beginWork, beginFailedWork } = ReactFiberBeginWork(
@@ -348,7 +348,7 @@ module.exports = function<T, P, I, TI, C, CX>(config : HostConfig<T, P, I, TI, C
       firstEffect = finishedWork.firstEffect;
     }
 
-    prepareForCommit();
+    const commitInfo = prepareForCommit();
 
     // Commit all the side-effects within a tree. We'll do this in two passes.
     // The first pass performs all the host insertions, updates, deletions and
@@ -369,7 +369,7 @@ module.exports = function<T, P, I, TI, C, CX>(config : HostConfig<T, P, I, TI, C
       }
     }
 
-    resetAfterCommit();
+    resetAfterCommit(commitInfo);
 
     // In the second pass we'll perform all life-cycles and ref callbacks.
     // Life-cycles happen as a separate pass so that all placements, updates,