diff --git a/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactory.java b/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactory.java
index 99b5c1dfea..73a18dbf33 100644
--- a/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactory.java
+++ b/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactory.java
@@ -97,38 +97,63 @@ public CommittedBundle<T> commit(final Instant synchronizedCompletionTime) {
       checkState(!committed, "Can't commit already committed bundle %s", this);
       committed = true;
       final Iterable<WindowedValue<T>> committedElements = elements.build();
-      return new CommittedBundle<T>() {
-        @Override
-        @Nullable
-        public Object getKey() {
-          return key;
-        }
-
-        @Override
-        public Iterable<WindowedValue<T>> getElements() {
-          return committedElements;
-        }
-
-        @Override
-        public PCollection<T> getPCollection() {
-          return pcollection;
-        }
-
-        @Override
-        public Instant getSynchronizedProcessingOutputWatermark() {
-          return synchronizedCompletionTime;
-        }
-
-        @Override
-        public String toString() {
-          return MoreObjects.toStringHelper(this)
-              .omitNullValues()
-              .add("pcollection", pcollection)
-              .add("key", key)
-              .add("elements", committedElements)
-              .toString();
-        }
-      };
+      return new CommittedInProcessBundle<>(
+          pcollection, key, committedElements, synchronizedCompletionTime);
+    }
+  }
+
+  private static class CommittedInProcessBundle<T> implements CommittedBundle<T> {
+    public CommittedInProcessBundle(
+        PCollection<T> pcollection,
+        Object key,
+        Iterable<WindowedValue<T>> committedElements,
+        Instant synchronizedCompletionTime) {
+      this.pcollection = pcollection;
+      this.key = key;
+      this.committedElements = committedElements;
+      this.synchronizedCompletionTime = synchronizedCompletionTime;
+    }
+
+    private final PCollection<T> pcollection;
+    private final Object key;
+    private final Iterable<WindowedValue<T>> committedElements;
+    private final Instant synchronizedCompletionTime;
+
+    @Override
+    @Nullable
+    public Object getKey() {
+      return key;
+    }
+
+    @Override
+    public Iterable<WindowedValue<T>> getElements() {
+      return committedElements;
+    }
+
+    @Override
+    public PCollection<T> getPCollection() {
+      return pcollection;
+    }
+
+    @Override
+    public Instant getSynchronizedProcessingOutputWatermark() {
+      return synchronizedCompletionTime;
+    }
+
+    @Override
+    public String toString() {
+      return MoreObjects.toStringHelper(this)
+          .omitNullValues()
+          .add("pcollection", pcollection)
+          .add("key", key)
+          .add("elements", committedElements)
+          .toString();
+    }
+
+    @Override
+    public CommittedBundle<T> withElements(Iterable<WindowedValue<T>> elements) {
+      return new CommittedInProcessBundle<>(
+          pcollection, key, ImmutableList.copyOf(elements), synchronizedCompletionTime);
     }
   }
 }
diff --git a/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessPipelineRunner.java b/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessPipelineRunner.java
index 3e333399a4..297e9e8ed9 100644
--- a/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessPipelineRunner.java
+++ b/sdk/src/main/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessPipelineRunner.java
@@ -149,6 +149,19 @@ public static interface CommittedBundle<T> {
      * timers that fired to produce this bundle.
      */
     Instant getSynchronizedProcessingOutputWatermark();
+
+    /**
+     * Return a new {@link CommittedBundle} that is like this one, except calls to
+     * {@link #getElements()} will return the provided elements. This bundle is unchanged.
+     *
+     * <p>
+     * The value of the {@link #getSynchronizedProcessingOutputWatermark() synchronized processing
+     * output watermark} of the returned {@link CommittedBundle} is equal to the value returned from
+     * the current bundle. This is used to ensure a {@link PTransform} that could not complete
+     * processing on input elements properly holds the synchronized processing time to the
+     * appropriate value.
+     */
+    CommittedBundle<T> withElements(Iterable<WindowedValue<T>> elements);
   }
 
   /**
diff --git a/sdk/src/test/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactoryTest.java b/sdk/src/test/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactoryTest.java
index 9b4e630042..a88f6b3ddc 100644
--- a/sdk/src/test/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactoryTest.java
+++ b/sdk/src/test/java/com/google/cloud/dataflow/sdk/runners/inprocess/InProcessBundleFactoryTest.java
@@ -1,4 +1,4 @@
-  /*
+/*
  * Copyright (C) 2016 Google Inc.
  *
  * Licensed under the Apache License, Version 2.0 (the "License"); you may not
@@ -25,6 +25,8 @@
 import com.google.cloud.dataflow.sdk.testing.TestPipeline;
 import com.google.cloud.dataflow.sdk.transforms.Create;
 import com.google.cloud.dataflow.sdk.transforms.WithKeys;
+import com.google.cloud.dataflow.sdk.transforms.windowing.IntervalWindow;
+import com.google.cloud.dataflow.sdk.transforms.windowing.PaneInfo;
 import com.google.cloud.dataflow.sdk.util.WindowedValue;
 import com.google.cloud.dataflow.sdk.values.KV;
 import com.google.cloud.dataflow.sdk.values.PCollection;
@@ -94,7 +96,8 @@ public void keyedWithKeyShouldCreateKeyedBundle() {
     createKeyedBundle(new Object());
   }
 
-  private <T> void afterCommitGetElementsShouldHaveAddedElements(Iterable<WindowedValue<T>> elems) {
+  private <T> CommittedBundle<T>
+  afterCommitGetElementsShouldHaveAddedElements(Iterable<WindowedValue<T>> elems) {
     PCollection<T> pcollection = TestPipeline.create().apply(Create.<T>of());
 
     UncommittedBundle<T> bundle = bundleFactory.createRootBundle(pcollection);
@@ -105,7 +108,10 @@ private <T> void afterCommitGetElementsShouldHaveAddedElements(Iterable<Windowed
     }
     Matcher<Iterable<? extends WindowedValue<T>>> containsMatcher =
         Matchers.<WindowedValue<T>>containsInAnyOrder(expectations);
-    assertThat(bundle.commit(Instant.now()).getElements(), containsMatcher);
+    CommittedBundle<T> committed = bundle.commit(Instant.now());
+    assertThat(committed.getElements(), containsMatcher);
+
+    return committed;
   }
 
   @Test
@@ -122,6 +128,36 @@ public void getElementsAfterAddShouldReturnAddedElements() {
     afterCommitGetElementsShouldHaveAddedElements(ImmutableList.of(firstValue, secondValue));
   }
 
+  @SuppressWarnings("unchecked")
+  @Test
+  public void withElementsShouldReturnIndependentBundle() {
+    WindowedValue<Integer> firstValue = WindowedValue.valueInGlobalWindow(1);
+    WindowedValue<Integer> secondValue =
+        WindowedValue.timestampedValueInGlobalWindow(2, new Instant(1000L));
+
+    CommittedBundle<Integer> committed =
+        afterCommitGetElementsShouldHaveAddedElements(ImmutableList.of(firstValue, secondValue));
+
+    WindowedValue<Integer> firstReplacement =
+        WindowedValue.of(
+            9,
+            new Instant(2048L),
+            new IntervalWindow(new Instant(2044L), Instant.now()),
+            PaneInfo.NO_FIRING);
+    WindowedValue<Integer> secondReplacement =
+        WindowedValue.timestampedValueInGlobalWindow(-1, Instant.now());
+    CommittedBundle<Integer> withed =
+        committed.withElements(ImmutableList.of(firstReplacement, secondReplacement));
+
+    assertThat(withed.getElements(), containsInAnyOrder(firstReplacement, secondReplacement));
+    assertThat(committed.getElements(), containsInAnyOrder(firstValue, secondValue));
+    assertThat(withed.getKey(), equalTo(committed.getKey()));
+    assertThat(withed.getPCollection(), equalTo(committed.getPCollection()));
+    assertThat(
+        withed.getSynchronizedProcessingOutputWatermark(),
+        equalTo(committed.getSynchronizedProcessingOutputWatermark()));
+  }
+
   @Test
   public void addAfterCommitShouldThrowException() {
     PCollection<Integer> pcollection = TestPipeline.create().apply(Create.<Integer>of());