diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index ab541b937b2..b97d5aa526b 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -41,6 +41,13 @@ New Features
   faster intersection by avoiding loading positions in certain cases.
   (Paul Elschot, Robert Muir via Mike McCandless)
 
+Optimizations
+
+* LUCENE-6379: IndexWriter.deleteDocuments(Query...) now detects if
+  one of the queries is MatchAllDocsQuery and just invokes the much
+  faster IndexWriter.deleteAll in that case (Robert Muir, Adrien
+  Grand, Mike McCandless)
+
 ======================= Lucene 5.1.0 =======================
 
 New Features
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 2893eea53ca..a64be82aef2 100644
--- a/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
+++ b/lucene/core/src/java/org/apache/lucene/index/IndexWriter.java
@@ -32,8 +32,8 @@ import java.util.Iterator;
 import java.util.LinkedList;
 import java.util.List;
 import java.util.Locale;
-import java.util.Map;
 import java.util.Map.Entry;
+import java.util.Map;
 import java.util.Queue;
 import java.util.Set;
 import java.util.concurrent.atomic.AtomicInteger;
@@ -47,6 +47,7 @@ import org.apache.lucene.index.DocValuesUpdate.BinaryDocValuesUpdate;
 import org.apache.lucene.index.DocValuesUpdate.NumericDocValuesUpdate;
 import org.apache.lucene.index.FieldInfos.FieldNumbers;
 import org.apache.lucene.index.IndexWriterConfig.OpenMode;
+import org.apache.lucene.search.MatchAllDocsQuery;
 import org.apache.lucene.search.Query;
 import org.apache.lucene.store.AlreadyClosedException;
 import org.apache.lucene.store.Directory;
@@ -1315,6 +1316,15 @@ public class IndexWriter implements Closeable, TwoPhaseCommit, Accountable {
    */
   public void deleteDocuments(Query... queries) throws IOException {
     ensureOpen();
+
+    // LUCENE-6379: Specialize MatchAllDocsQuery
+    for(Query query : queries) {
+      if (query.getClass() == MatchAllDocsQuery.class) {
+        deleteAll();
+        return;
+      }
+    }
+
     try {
       if (docWriter.deleteQueries(queries)) {
         processEvents(true, false);
diff --git a/lucene/core/src/java/org/apache/lucene/search/MatchAllDocsQuery.java b/lucene/core/src/java/org/apache/lucene/search/MatchAllDocsQuery.java
index 4089bc050e8..f13667ad401 100644
--- a/lucene/core/src/java/org/apache/lucene/search/MatchAllDocsQuery.java
+++ b/lucene/core/src/java/org/apache/lucene/search/MatchAllDocsQuery.java
@@ -30,7 +30,7 @@ import org.apache.lucene.util.ToStringUtils;
  * A query that matches all documents.
  *
  */
-public class MatchAllDocsQuery extends Query {
+public final class MatchAllDocsQuery extends Query {
 
   private class MatchAllScorer extends Scorer {
     final float score;
@@ -88,7 +88,7 @@ public class MatchAllDocsQuery extends Query {
     private float queryWeight;
     private float queryNorm;
 
-    public MatchAllDocsWeight(IndexSearcher searcher) {
+    public MatchAllDocsWeight() {
       super(MatchAllDocsQuery.this);
     }
 
@@ -130,7 +130,7 @@ public class MatchAllDocsQuery extends Query {
 
   @Override
   public Weight createWeight(IndexSearcher searcher, boolean needsScores) {
-    return new MatchAllDocsWeight(searcher);
+    return new MatchAllDocsWeight();
   }
 
   @Override
diff --git a/lucene/core/src/test/org/apache/lucene/index/TestIndexWriterDeleteByQuery.java b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriterDeleteByQuery.java
new file mode 100644
index 00000000000..10023506298
--- /dev/null
+++ b/lucene/core/src/test/org/apache/lucene/index/TestIndexWriterDeleteByQuery.java
@@ -0,0 +1,71 @@
+package org.apache.lucene.index;
+
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import org.apache.lucene.document.Document;
+import org.apache.lucene.document.Field;
+import org.apache.lucene.search.MatchAllDocsQuery;
+import org.apache.lucene.store.Directory;
+import org.apache.lucene.util.LuceneTestCase;
+
+public class TestIndexWriterDeleteByQuery extends LuceneTestCase {
+
+  // LUCENE-6379
+  public void testDeleteMatchAllDocsQuery() throws Exception {
+    Directory dir = newDirectory();
+    IndexWriter w = new IndexWriter(dir, newIndexWriterConfig());
+    Document doc = new Document();
+    // Norms are disabled:
+    doc.add(newStringField("field", "foo", Field.Store.NO));
+    w.addDocument(doc);
+    DirectoryReader r = DirectoryReader.open(w, true);
+    FieldInfo fi = MultiFields.getMergedFieldInfos(r).fieldInfo("field");
+    assertNotNull(fi);
+    assertFalse(fi.hasNorms());
+    assertEquals(1, r.numDocs());
+    assertEquals(1, r.maxDoc());
+
+    w.deleteDocuments(new MatchAllDocsQuery());
+    DirectoryReader r2 = DirectoryReader.openIfChanged(r);
+    r.close();
+
+    assertNotNull(r2);
+    assertEquals(0, r2.numDocs());
+    assertEquals(0, r2.maxDoc());
+
+    // Confirm the omitNorms bit is in fact no longer set:
+    doc = new Document();
+    // Norms are disabled:
+    doc.add(newTextField("field", "foo", Field.Store.NO));
+    w.addDocument(doc);
+
+    DirectoryReader r3 = DirectoryReader.openIfChanged(r2);
+    r2.close();
+    assertNotNull(r3);
+    assertEquals(1, r3.numDocs());
+    assertEquals(1, r3.maxDoc());
+
+    // Make sure norms can come back to life for a field after deleting by MatchAllDocsQuery:
+    fi = MultiFields.getMergedFieldInfos(r3).fieldInfo("field");    
+    assertNotNull(fi);
+    assertTrue(fi.hasNorms());
+    r3.close();
+    w.close();
+    dir.close();
+  }
+}