diff --git a/scripts/fiber/tests-failing.txt b/scripts/fiber/tests-failing.txt
index 098d4df39e1..ed2077e38cb 100644
--- a/scripts/fiber/tests-failing.txt
+++ b/scripts/fiber/tests-failing.txt
@@ -72,6 +72,9 @@ src/renderers/art/__tests__/ReactART-test.js
 * resolves refs before componentDidMount
 * resolves refs before componentDidUpdate
 
+src/renderers/dom/__tests__/ReactDOMProduction-test.js
+* should throw with an error code in production
+
 src/renderers/dom/shared/__tests__/CSSPropertyOperations-test.js
 * should set style attribute when styles exist
 * should warn when using hyphenated style names
diff --git a/scripts/fiber/tests-passing.txt b/scripts/fiber/tests-passing.txt
index 0ba4d4a5c07..6ebc9360f2f 100644
--- a/scripts/fiber/tests-passing.txt
+++ b/scripts/fiber/tests-passing.txt
@@ -453,7 +453,6 @@ src/renderers/dom/__tests__/ReactDOMProduction-test.js
 * should use prod React
 * should handle a simple flow
 * should call lifecycle methods
-* should throw with an error code in production
 
 src/renderers/dom/fiber/__tests__/ReactDOMFiber-test.js
 * should render strings as children
@@ -846,18 +845,6 @@ src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js
 * splits deferred work on multiple roots
 * works on deferred roots in the order they were scheduled
 * handles interleaved deferred and animation work
-* performs animation work in animation callback
-* schedules deferred work in animation callback
-* schedules deferred work and performs animation work in animation callback
-* performs animation work and schedules deferred work in animation callback
-* performs deferred work in deferred callback if it has time
-* schedules deferred work in deferred callback if it runs out of time
-* performs animated work in deferred callback if it has time
-* performs animated work and deferred work in deferred callback if it has time
-* performs deferred and animated work work in deferred callback if it has time
-* schedules animated work in deferred callback if it runs out of time
-* schedules animated work and deferred work in deferred callback if it runs out of time
-* schedules deferred work and animated work in deferred callback if it runs out of time
 
 src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
 * can update child nodes of a host instance
@@ -878,6 +865,7 @@ src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
 * calls setState callback even if component bails out
 * calls componentWillUnmount after a deletion, even if nested
 * calls componentDidMount/Update after insertion/update
+* schedules sync updates when inside componentDidMount/Update
 * invokes ref callbacks after insertion/update/unmount
 * supports string refs
 
diff --git a/src/renderers/shared/fiber/ReactFiberScheduler.js b/src/renderers/shared/fiber/ReactFiberScheduler.js
index e3cb91cdeb3..c69395a4185 100644
--- a/src/renderers/shared/fiber/ReactFiberScheduler.js
+++ b/src/renderers/shared/fiber/ReactFiberScheduler.js
@@ -209,7 +209,10 @@ module.exports = function<T, P, I, TI, C>(config : HostConfig<T, P, I, TI, C>) {
     while (effectfulFiber) {
       if (effectfulFiber.effectTag & (Update | Callback)) {
         const current = effectfulFiber.alternate;
+        const previousPriorityContext = priorityContext;
+        priorityContext = TaskPriority;
         commitLifeCycles(current, effectfulFiber);
+        priorityContext = previousPriorityContext;
       }
       const next = effectfulFiber.nextEffect;
       // Ensure that we clean these up so that we don't accidentally keep them.
diff --git a/src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js b/src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js
index 220a69a2fb5..5808ab4c666 100644
--- a/src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js
+++ b/src/renderers/shared/fiber/__tests__/ReactIncrementalScheduling-test.js
@@ -449,373 +449,4 @@ describe('ReactIncrementalScheduling', () => {
     expect(ReactNoop.getChildren('b')).toEqual([span('b:3')]);
     expect(ReactNoop.getChildren('c')).toEqual([span('c:3')]);
   });
-
-  it('performs animation work in animation callback', () => {
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Animation work that will get performed during animation callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        });
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule animation work
-    ReactNoop.performAnimationWork(() => {
-      ReactNoop.renderToRootWithID(<Foo />, 'a');
-    });
-
-    // Flushing animation work should flush animation work scheduled inside it
-    ReactNoop.flushAnimationPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-  });
-
-  it('schedules deferred work in animation callback', () => {
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Deferred work that will get scheduled during animation callback
-        ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule animation work
-    ReactNoop.performAnimationWork(() => {
-      ReactNoop.renderToRootWithID(<Foo />, 'a');
-    });
-
-    // Flushing animation work should not flush the deferred work
-    ReactNoop.flushAnimationPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([]);
-
-    // Flush the deferred work
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-  });
-
-  it('schedules deferred work and performs animation work in animation callback', () => {
-    let hasScheduled = false;
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Deferred work that will get scheduled during animation callback
-        ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        // Animation work that will get performed during animation callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="c:1" />, 'c');
-        });
-        // Deferred work that will get scheduled during animation callback
-        ReactNoop.renderToRootWithID(<span prop="d:1" />, 'd');
-        hasScheduled = true;
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule animation work
-    ReactNoop.performAnimationWork(() => {
-      ReactNoop.renderToRootWithID(<Foo />, 'a');
-    });
-
-    // Flushing animation work should flush animation work scheduled inside it
-    ReactNoop.flushAnimationPri();
-    expect(hasScheduled).toBe(true);
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([]);
-    expect(ReactNoop.getChildren('c')).toEqual([span('c:1')]);
-    expect(ReactNoop.getChildren('d')).toEqual([]);
-
-    // Flush the deferred work
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-    expect(ReactNoop.getChildren('c')).toEqual([span('c:1')]);
-    expect(ReactNoop.getChildren('d')).toEqual([span('d:1')]);
-  });
-
-  it('performs animation work and schedules deferred work in animation callback', () => {
-    let hasScheduled = false;
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Animation work that will get performed during animation callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        });
-        // Deferred work that will get scheduled during animation callback
-        ReactNoop.renderToRootWithID(<span prop="c:1" />, 'c');
-        // Animation work that will get performed during animation callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="d:1" />, 'd');
-        });
-        hasScheduled = true;
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule animation work
-    ReactNoop.performAnimationWork(() => {
-      ReactNoop.renderToRootWithID(<Foo />, 'a');
-    });
-
-    // Flushing animation work should flush animation work scheduled inside it
-    ReactNoop.flushAnimationPri();
-    expect(hasScheduled).toBe(true);
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-    expect(ReactNoop.getChildren('c')).toEqual([]);
-    expect(ReactNoop.getChildren('d')).toEqual([span('d:1')]);
-
-    // Flush the deferred work
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-    expect(ReactNoop.getChildren('c')).toEqual([span('c:1')]);
-    expect(ReactNoop.getChildren('d')).toEqual([span('d:1')]);
-  });
-
-  it('performs deferred work in deferred callback if it has time', () => {
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Deferred work that will get performed during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flushing deferred work should flush deferred work scheduled inside it
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-  });
-
-  it('schedules deferred work in deferred callback if it runs out of time', () => {
-    let hasScheduled = false;
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Deferred work that will get scheduled during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        hasScheduled = true;
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flush just enough deferred work to schedule more deferred work
-    ReactNoop.flushDeferredPri(20);
-    expect(hasScheduled).toBe(true);
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([]);
-
-    // Flush the rest of the deferred work
-    ReactNoop.flushDeferredPri(15);
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-  });
-
-  it('performs animated work in deferred callback if it has time', () => {
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Animated work that will get performed during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        });
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flushing deferred work should flush animated work scheduled inside it
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-  });
-
-  it('performs animated work and deferred work in deferred callback if it has time', () => {
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Deferred work that will get performed during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        // Animation work that will get performed during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="c:1" />, 'c');
-        });
-        // Deferred work that will get performed during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="d:1" />, 'd');
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flushing deferred work should flush both deferred and animated work scheduled inside it
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-    expect(ReactNoop.getChildren('c')).toEqual([span('c:1')]);
-    expect(ReactNoop.getChildren('d')).toEqual([span('d:1')]);
-  });
-
-  it('performs deferred and animated work work in deferred callback if it has time', () => {
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Animation work that will get performed during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        });
-        // Deferred work that will get performed during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="c:1" />, 'c');
-        // Animation work that will get performed during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="d:1" />, 'd');
-        });
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flushing deferred work should flush both deferred and animated work scheduled inside it
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-    expect(ReactNoop.getChildren('c')).toEqual([span('c:1')]);
-    expect(ReactNoop.getChildren('d')).toEqual([span('d:1')]);
-  });
-
-  it('schedules animated work in deferred callback if it runs out of time', () => {
-    let hasScheduled = false;
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Animated work that will get scheduled during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        });
-        hasScheduled = true;
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flush just enough deferred work to schedule animated work
-    ReactNoop.flushDeferredPri(20);
-    expect(hasScheduled).toBe(true);
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([]);
-
-    // Flush the rest of work in an animated callback.
-    ReactNoop.flushAnimationPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-  });
-
-  it('schedules animated work and deferred work in deferred callback if it runs out of time', () => {
-    let isScheduled = false;
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Deferred work that will get performed during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        // Animation work that will get performed during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="c:1" />, 'c');
-        });
-        // Deferred work that will get performed during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="d:1" />, 'd');
-        isScheduled = true;
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flushing deferred work should schedule both deferred and animated work
-    ReactNoop.flushDeferredPri(20);
-    expect(isScheduled).toBe(true);
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([]);
-    expect(ReactNoop.getChildren('c')).toEqual([]);
-    expect(ReactNoop.getChildren('d')).toEqual([]);
-
-    // Flush the rest of the work
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-    expect(ReactNoop.getChildren('c')).toEqual([span('c:1')]);
-    expect(ReactNoop.getChildren('d')).toEqual([span('d:1')]);
-  });
-
-  it('schedules deferred work and animated work in deferred callback if it runs out of time', () => {
-    let isScheduled = false;
-    class Foo extends React.Component {
-      componentDidMount() {
-        // Animation work that will get performed during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="b:1" />, 'b');
-        });
-        // Deferred work that will get performed during deferred callback
-        ReactNoop.renderToRootWithID(<span prop="c:1" />, 'c');
-        // Animation work that will get performed during deferred callback
-        ReactNoop.performAnimationWork(() => {
-          ReactNoop.renderToRootWithID(<span prop="d:1" />, 'd');
-        });
-        isScheduled = true;
-      }
-      render() {
-        return <span prop="a:1" />;
-      }
-    }
-
-    // Schedule deferred work
-    ReactNoop.renderToRootWithID(<Foo />, 'a');
-
-    // Flushing deferred work should schedule both deferred and animated work
-    ReactNoop.flushDeferredPri(20);
-    expect(isScheduled).toBe(true);
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([]);
-    expect(ReactNoop.getChildren('c')).toEqual([]);
-    expect(ReactNoop.getChildren('d')).toEqual([]);
-
-    // Flush the rest of the work
-    ReactNoop.flushDeferredPri();
-    expect(ReactNoop.getChildren('a')).toEqual([span('a:1')]);
-    expect(ReactNoop.getChildren('b')).toEqual([span('b:1')]);
-    expect(ReactNoop.getChildren('c')).toEqual([span('c:1')]);
-    expect(ReactNoop.getChildren('d')).toEqual([span('d:1')]);
-  });
 });
diff --git a/src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js b/src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
index 9e64dc43c13..a9294e2501f 100644
--- a/src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
+++ b/src/renderers/shared/fiber/__tests__/ReactIncrementalSideEffects-test.js
@@ -1036,6 +1036,66 @@ describe('ReactIncrementalSideEffects', () => {
 
   });
 
+  it('schedules sync updates when inside componentDidMount/Update', () => {
+    var instance;
+    var ops = [];
+
+    class Foo extends React.Component {
+      state = { tick: 0 };
+
+      componentDidMount() {
+        ops.push('componentDidMount (before setState): ' + this.state.tick);
+        this.setState({ tick: 1 });
+        // We're in a batch. Update hasn't flushed yet.
+        ops.push('componentDidMount (after setState): ' + this.state.tick);
+      }
+
+      componentDidUpdate() {
+        ops.push('componentDidUpdate: ' + this.state.tick);
+        if (this.state.tick === 2) {
+          ops.push('componentDidUpdate (before setState): ' + this.state.tick);
+          this.setState({ tick: 3 });
+          ops.push('componentDidUpdate (after setState): ' + this.state.tick);
+          // We're in a batch. Update hasn't flushed yet.
+        }
+      }
+
+      render() {
+        ops.push('render: ' + this.state.tick);
+        instance = this;
+        return <span prop={this.state.tick} />;
+      }
+    }
+
+    ReactNoop.render(<Foo />);
+
+    ReactNoop.flushDeferredPri(20);
+    expect(ops).toEqual([
+      'render: 0',
+      'componentDidMount (before setState): 0',
+      'componentDidMount (after setState): 0',
+      // If the setState inside componentDidMount were deferred, there would be
+      // no more ops. Because it has Task priority, we get these ops, too:
+      'render: 1',
+      'componentDidUpdate: 1',
+    ]);
+
+    ops = [];
+    instance.setState({ tick: 2 });
+    ReactNoop.flushDeferredPri(20);
+
+    expect(ops).toEqual([
+      'render: 2',
+      'componentDidUpdate: 2',
+      'componentDidUpdate (before setState): 2',
+      'componentDidUpdate (after setState): 2',
+      // If the setState inside componentDidUpdate were deferred, there would be
+      // no more ops. Because it has Task priority, we get these ops, too:
+      'render: 3',
+      'componentDidUpdate: 3',
+    ]);
+  });
+
   it('invokes ref callbacks after insertion/update/unmount', () => {
 
     var classInstance = null;