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 a73fdb1d3ba..bfa04feb1bb 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
@@ -3159,7 +3159,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit, Accountable,
           // Commit thread timed out waiting for this merge and moved on. No need to manipulate toCommit.
           return;
         }
-        if (isAborted() == false) {
+        if (committed) {
           deleter.incRef(this.info.files());
           // Resolve "live" SegmentInfos segments to their toCommit cloned equivalents, based on segment name.
           Set<String> mergedSegmentNames = new HashSet<>();
@@ -4076,6 +4076,7 @@ public class IndexWriter implements Closeable, TwoPhaseCommit, Accountable,
     }
 
     try (Closeable finalizer = this::checkpoint) {
+      merge.committed = true;
       // Must close before checkpoint, otherwise IFD won't be
       // able to delete the held-open files from the merge
       // readers:
diff --git a/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java b/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java
index c191c6571ce..ad4069d5358 100644
--- a/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java
+++ b/lucene/core/src/java/org/apache/lucene/index/MergePolicy.java
@@ -225,6 +225,8 @@ public abstract class MergePolicy {
     public final int totalMaxDoc;
     Throwable error;
 
+    boolean committed; // Set by IndexWriter once the merge has been committed to disk
+
     /** Sole constructor.
      * @param segments List of {@link SegmentCommitInfo}s
      *        to be merged. */
diff --git a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java
index f58ecee67b3..8a463efd835 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriterMergePolicy.java
@@ -19,10 +19,7 @@ package org.apache.lucene.index;
 
 import java.io.IOException;
 import java.util.ArrayList;
-import java.util.Collection;
 import java.util.List;
-import java.util.concurrent.CountDownLatch;
-import java.util.concurrent.atomic.AtomicInteger;
 
 import org.apache.lucene.analysis.MockAnalyzer;
 import org.apache.lucene.document.Document;
@@ -32,11 +29,31 @@ import org.apache.lucene.search.IndexSearcher;
 import org.apache.lucene.search.MatchAllDocsQuery;
 import org.apache.lucene.store.Directory;
 
-import org.apache.lucene.util.LineFileDocs;
 import org.apache.lucene.util.LuceneTestCase;
 
 public class TestIndexWriterMergePolicy extends LuceneTestCase {
-  
+
+  private static final MergePolicy MERGE_ON_COMMIT_POLICY = new LogDocMergePolicy() {
+    @Override
+    public MergeSpecification findFullFlushMerges(MergeTrigger mergeTrigger, SegmentInfos segmentInfos, MergeContext mergeContext) {
+      // Optimize down to a single segment on commit
+      if (mergeTrigger == MergeTrigger.COMMIT && segmentInfos.size() > 1) {
+        List<SegmentCommitInfo> nonMergingSegments = new ArrayList<>();
+        for (SegmentCommitInfo sci : segmentInfos) {
+          if (mergeContext.getMergingSegments().contains(sci) == false) {
+            nonMergingSegments.add(sci);
+          }
+        }
+        if (nonMergingSegments.size() > 1) {
+          MergeSpecification mergeSpecification = new MergeSpecification();
+          mergeSpecification.add(new OneMerge(nonMergingSegments));
+          return mergeSpecification;
+        }
+      }
+      return null;
+    }
+  };
+
   // Test the normal case
   public void testNormalCase() throws IOException {
     Directory dir = newDirectory();
@@ -286,7 +303,8 @@ public class TestIndexWriterMergePolicy extends LuceneTestCase {
     assertSetters(new LogDocMergePolicy());
   }
 
-  public void testMergeOnCommit() throws IOException, InterruptedException {
+  // Test basic semantics of merge on commit
+  public void testMergeOnCommit() throws IOException {
     Directory dir = newDirectory();
 
     IndexWriter firstWriter = new IndexWriter(dir, newIndexWriterConfig(new MockAnalyzer(random()))
@@ -298,118 +316,33 @@ public class TestIndexWriterMergePolicy extends LuceneTestCase {
     DirectoryReader firstReader = DirectoryReader.open(firstWriter);
     assertEquals(5, firstReader.leaves().size());
     firstReader.close();
-    firstWriter.close();
+    firstWriter.close(); // When this writer closes, it does not merge on commit.
 
-    MergePolicy mergeOnCommitPolicy = new LogDocMergePolicy() {
-      @Override
-      public MergeSpecification findFullFlushMerges(MergeTrigger mergeTrigger, SegmentInfos segmentInfos, MergeContext mergeContext) {
-        // Optimize down to a single segment on commit
-        if (mergeTrigger == MergeTrigger.COMMIT && segmentInfos.size() > 1) {
-          List<SegmentCommitInfo> nonMergingSegments = new ArrayList<>();
-          for (SegmentCommitInfo sci : segmentInfos) {
-            if (mergeContext.getMergingSegments().contains(sci) == false) {
-              nonMergingSegments.add(sci);
-            }
-          }
-          if (nonMergingSegments.size() > 1) {
-            MergeSpecification mergeSpecification = new MergeSpecification();
-            mergeSpecification.add(new OneMerge(nonMergingSegments));
-            return mergeSpecification;
-          }
-        }
-        return null;
-      }
-    };
-
-    AtomicInteger abandonedMerges = new AtomicInteger(0);
     IndexWriterConfig iwc = newIndexWriterConfig(new MockAnalyzer(random()))
-        .setMergePolicy(mergeOnCommitPolicy)
-        .setIndexWriterEvents(new IndexWriterEvents() {
-          @Override
-          public void beginMergeOnCommit() {
+        .setMergePolicy(MERGE_ON_COMMIT_POLICY);
 
-          }
-
-          @Override
-          public void finishMergeOnCommit() {
-
-          }
-
-          @Override
-          public void abandonedMergesOnCommit(int abandonedCount) {
-            abandonedMerges.incrementAndGet();
-          }
-        });
     IndexWriter writerWithMergePolicy = new IndexWriter(dir, iwc);
-
-    writerWithMergePolicy.commit();
+    writerWithMergePolicy.commit(); // No changes. Commit doesn't trigger a merge.
 
     DirectoryReader unmergedReader = DirectoryReader.open(writerWithMergePolicy);
-    assertEquals(5, unmergedReader.leaves().size()); // Don't merge unless there's a change
+    assertEquals(5, unmergedReader.leaves().size());
     unmergedReader.close();
 
     TestIndexWriter.addDoc(writerWithMergePolicy);
-    writerWithMergePolicy.commit();
+    writerWithMergePolicy.commit(); // Doc added, do merge on commit.
+    assertEquals(1, writerWithMergePolicy.getSegmentCount()); //
 
     DirectoryReader mergedReader = DirectoryReader.open(writerWithMergePolicy);
-    assertEquals(1, mergedReader.leaves().size()); // Now we merge on commit
+    assertEquals(1, mergedReader.leaves().size());
     mergedReader.close();
 
-    LineFileDocs lineFileDocs = new LineFileDocs(random());
-    int docCount = atLeast(1000);
-    AtomicInteger indexedDocs = new AtomicInteger(0);
-    int numIndexingThreads = atLeast(2);
-    CountDownLatch startingGun = new CountDownLatch(1);
-    Collection<Thread> indexingThreads = new ArrayList<>();
-    for (int i = 0; i < numIndexingThreads; i++) {
-      Thread t = new Thread(() -> {
-        try {
-          startingGun.await();
-          while (indexedDocs.getAndIncrement() < docCount) {
-            writerWithMergePolicy.addDocument(lineFileDocs.nextDoc());
-            if (rarely()) {
-              writerWithMergePolicy.commit();
-            }
-          }
-        } catch (IOException | InterruptedException e) {
-          e.printStackTrace();
-          fail();
-        }
-      });
-      t.start();
-      indexingThreads.add(t);
-    }
-    startingGun.countDown();
-    for (Thread t : indexingThreads) {
-      t.join();
-    }
-    for (int i = 0; i < 50; i++) {
-      // Wait for pending merges to finish
-      synchronized (writerWithMergePolicy) {
-        if (writerWithMergePolicy.getMergingSegments().isEmpty()) {
-          break;
-        }
-      }
-      Thread.sleep(100);
-    }
-    abandonedMerges.set(0);
-    // Ensure there's at least one pending change so merge on commit happens
-    TestIndexWriter.addDoc(writerWithMergePolicy);
-    writerWithMergePolicy.commit();
-    if (abandonedMerges.get() == 0) {
-      assertEquals(1, writerWithMergePolicy.listOfSegmentCommitInfos().size());
-    } else {
-      assertNotEquals(1, writerWithMergePolicy.listOfSegmentCommitInfos().size());
-    }
-
     try (IndexReader reader = writerWithMergePolicy.getReader()) {
       IndexSearcher searcher = new IndexSearcher(reader);
-      assertEquals(docCount + 7, reader.numDocs());
-      assertEquals(docCount + 7, searcher.count(new MatchAllDocsQuery()));
+      assertEquals(6, reader.numDocs());
+      assertEquals(6, searcher.count(new MatchAllDocsQuery()));
     }
 
     writerWithMergePolicy.close();
-
     dir.close();
   }