diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 3b96df97b10..932555b0a3d 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -254,6 +254,9 @@ New Features
 * LUCENE-5063: FieldCache.DEFAULT.get(Ints|Longs) now uses bit-packing to save
   memory. (Adrien Grand)
 
+* LUCENE-5079: IndexWriter.hasUncommittedChanges() returns true if there are
+  changes that have not been committed. (yonik, Mike McCandless, Uwe Schindler)
+
 API Changes
 
 * LUCENE-5077: Make it easier to use compressed norms. Lucene42NormsFormat takes
diff --git a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
index 2cf0fe8f2d9..d891562b1ae 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
@@ -214,7 +214,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit {
   private final Analyzer analyzer;    // how to analyze text
 
   private volatile long changeCount; // increments every time a change is completed
-  private long lastCommitChangeCount; // last changeCount that was committed
+  private volatile long lastCommitChangeCount; // last changeCount that was committed
 
   private List<SegmentInfoPerCommit> rollbackSegments;      // list of segmentInfo we will fallback to if the commit fails
 
@@ -2827,6 +2827,11 @@ public class IndexWriter implements Closeable, TwoPhaseCommit {
     commitInternal();
   }
 
+  /** Returns true if there are changes that have not been committed */
+  public final boolean hasUncommittedChanges() {
+    return changeCount != lastCommitChangeCount;
+  }
+
   private final void commitInternal() throws IOException {
 
     if (infoStream.isEnabled("IW")) {
@@ -2866,8 +2871,8 @@ public class IndexWriter implements Closeable, TwoPhaseCommit {
         if (infoStream.isEnabled("IW")) {
           infoStream.message("IW", "commit: wrote segments file \"" + pendingCommit.getSegmentsFileName() + "\"");
         }
-        lastCommitChangeCount = pendingCommitChangeCount;
         segmentInfos.updateGeneration(pendingCommit);
+        lastCommitChangeCount = pendingCommitChangeCount;
         rollbackSegments = pendingCommit.createBackupSegmentInfos();
         deleter.checkpoint(pendingCommit, true);
       } finally {
diff --git a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
index 95e9fef1382..8caafd6dcba 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriter.java
@@ -2209,4 +2209,27 @@ public class TestIndexWriter extends LuceneTestCase {
       dir.close();
     }
   }
+
+  public void testHasUncommittedChanges() throws IOException {
+    Directory dir = newDirectory();
+    IndexWriter writer = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT, new MockAnalyzer(random())));
+    assertTrue(writer.hasUncommittedChanges());  // this will be true because a commit will create an empty index
+    Document doc = new Document();
+    doc.add(newTextField("myfield", "a b c", Field.Store.NO));
+    writer.addDocument(doc);
+    assertTrue(writer.hasUncommittedChanges());
+    writer.commit();
+    assertFalse(writer.hasUncommittedChanges());
+    writer.addDocument(doc);
+    assertTrue(writer.hasUncommittedChanges());
+    writer.close();
+
+    writer = new IndexWriter(dir, newIndexWriterConfig( TEST_VERSION_CURRENT, new MockAnalyzer(random())));
+    assertFalse(writer.hasUncommittedChanges());
+    writer.addDocument(doc);
+    assertTrue(writer.hasUncommittedChanges());
+
+    writer.close();
+    dir.close();
+  }
 }