diff --git a/lucene/CHANGES.txt b/lucene/CHANGES.txt
index 59779ded566..2a8397c1224 100644
--- a/lucene/CHANGES.txt
+++ b/lucene/CHANGES.txt
@@ -91,6 +91,9 @@ API Changes
   incorrect results for Numeric fields using precisionStep
   (hossman, Robert Muir)
 
+* LUCENE-6511: Add missing ConcurrentMergeScheduler.getAutoIOThrottle
+  getter (Simon Willnauer, Mike McCandless)
+
 Bug fixes
 
 * LUCENE-6500: ParallelCompositeReader did not always call
diff --git a/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java b/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java
index 641598323df..edbacd53303 100644
--- a/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java
+++ b/lucene/core/src/java/org/apache/lucene/index/ConcurrentMergeScheduler.java
@@ -214,6 +214,11 @@ public class ConcurrentMergeScheduler extends MergeScheduler {
     updateMergeThreads();
   }
 
+  /** Returns true if auto IO throttling is currently enabled. */
+  public synchronized boolean getAutoIOThrottle() {
+    return doAutoIOThrottle;
+  }
+
   /** Returns the currently set per-merge IO writes rate limit, if {@link #enableAutoIOThrottle}
    *  was called, else {@code Double.POSITIVE_INFINITY}. */
   public synchronized double getIORateLimitMBPerSec() {
diff --git a/lucene/core/src/test/org/apache/lucene/index/TestConcurrentMergeScheduler.java b/lucene/core/src/test/org/apache/lucene/index/TestConcurrentMergeScheduler.java
index ba8c8b746b0..083e4269ac0 100644
--- a/lucene/core/src/test/org/apache/lucene/index/TestConcurrentMergeScheduler.java
+++ b/lucene/core/src/test/org/apache/lucene/index/TestConcurrentMergeScheduler.java
@@ -635,6 +635,14 @@ public class TestConcurrentMergeScheduler extends LuceneTestCase {
     assertEquals(6, cms.getMaxMergeCount());
   }
 
+  public void testAutoIOThrottleGetter() throws Exception {
+    ConcurrentMergeScheduler cms = new ConcurrentMergeScheduler();
+    cms.disableAutoIOThrottle();
+    assertFalse(cms.getAutoIOThrottle());
+    cms.enableAutoIOThrottle();
+    assertTrue(cms.getAutoIOThrottle());
+  }
+
   public void testNonSpinningDefaults() throws Exception {
     ConcurrentMergeScheduler cms = new ConcurrentMergeScheduler();
     cms.setDefaultMaxMergesAndThreads(false);
diff --git a/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java b/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java
index 51306dbb350..5463dcec191 100644
--- a/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java
+++ b/lucene/test-framework/src/java/org/apache/lucene/util/LuceneTestCase.java
@@ -915,6 +915,7 @@ public abstract class LuceneTestCase extends Assert {
       cms.setMaxMergesAndThreads(maxMergeCount, maxThreadCount);
       if (random().nextBoolean()) {
         cms.disableAutoIOThrottle();
+        assertFalse(cms.getAutoIOThrottle());
       }
       cms.setForceMergeMBPerSec(10 + 10*random().nextDouble());
       c.setMergeScheduler(cms);
@@ -1180,11 +1181,18 @@ public abstract class LuceneTestCase extends Assert {
       // change CMS merge parameters
       MergeScheduler ms = c.getMergeScheduler();
       if (ms instanceof ConcurrentMergeScheduler) {
+        ConcurrentMergeScheduler cms = (ConcurrentMergeScheduler) ms;
         int maxThreadCount = TestUtil.nextInt(r, 1, 4);
         int maxMergeCount = TestUtil.nextInt(r, maxThreadCount, maxThreadCount + 4);
-        ((ConcurrentMergeScheduler)ms).setMaxMergesAndThreads(maxMergeCount, maxThreadCount);
+        boolean enableAutoIOThrottle = random().nextBoolean();
+        if (enableAutoIOThrottle) {
+          cms.enableAutoIOThrottle();
+        } else {
+          cms.disableAutoIOThrottle();
+        }
+        cms.setMaxMergesAndThreads(maxMergeCount, maxThreadCount);
+        didChange = true;
       }
-      didChange = true;
     }
     
     if (rarely(r)) {