diff --git a/hadoop-common-project/hadoop-common/CHANGES.txt b/hadoop-common-project/hadoop-common/CHANGES.txt
index 86deddeb5f..ecf895f1cb 100644
--- a/hadoop-common-project/hadoop-common/CHANGES.txt
+++ b/hadoop-common-project/hadoop-common/CHANGES.txt
@@ -297,6 +297,9 @@ Release 2.0.3-alpha - Unreleased
     HADOOP-8804. Improve Web UIs when the wildcard address is used.
     (Senthil Kumar via eli)
 
+    HADOOP-8894. GenericTestUtils.waitFor should dump thread stacks on timeout
+    (todd)
+
   OPTIMIZATIONS
 
     HADOOP-8866. SampleQuantiles#query is O(N^2) instead of O(N). (Andrew Wang
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/GenericTestUtils.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/GenericTestUtils.java
index 806df54718..2a361d9192 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/GenericTestUtils.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/GenericTestUtils.java
@@ -104,7 +104,10 @@ public static void waitFor(Supplier<Boolean> check,
       
       Thread.sleep(checkEveryMillis);
     } while (Time.now() - st < waitForMillis);
-    throw new TimeoutException("Timed out waiting for condition");
+    
+    throw new TimeoutException("Timed out waiting for condition. " +
+        "Thread diagnostics:\n" +
+        TimedOutTestsListener.buildThreadDiagnosticString());
   }
   
   public static class LogCapturer {
diff --git a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/TimedOutTestsListener.java b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/TimedOutTestsListener.java
index a10edbbd27..220ab1daea 100644
--- a/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/TimedOutTestsListener.java
+++ b/hadoop-common-project/hadoop-common/src/test/java/org/apache/hadoop/test/TimedOutTestsListener.java
@@ -58,19 +58,28 @@ public void testFailure(Failure failure) throws Exception {
         && failure.getMessage().startsWith(TEST_TIMED_OUT_PREFIX)) {
       output.println("====> TEST TIMED OUT. PRINTING THREAD DUMP. <====");
       output.println();
-      DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss,SSS");
-      output.println(String.format("Timestamp: %s", dateFormat.format(new Date())));
-      output.println();
-      output.println(buildThreadDump());
-      
-      String deadlocksInfo = buildDeadlockInfo();
-      if (deadlocksInfo != null) {
-        output.println("====> DEADLOCKS DETECTED <====");
-        output.println();
-        output.println(deadlocksInfo);
-      }
+      output.print(buildThreadDiagnosticString());
     }
   }
+  
+  public static String buildThreadDiagnosticString() {
+    StringWriter sw = new StringWriter();
+    PrintWriter output = new PrintWriter(sw);
+    
+    DateFormat dateFormat = new SimpleDateFormat("yyyy-MM-dd hh:mm:ss,SSS");
+    output.println(String.format("Timestamp: %s", dateFormat.format(new Date())));
+    output.println();
+    output.println(buildThreadDump());
+    
+    String deadlocksInfo = buildDeadlockInfo();
+    if (deadlocksInfo != null) {
+      output.println("====> DEADLOCKS DETECTED <====");
+      output.println();
+      output.println(deadlocksInfo);
+    }
+
+    return sw.toString();
+  }
 
   static String buildThreadDump() {
     StringBuilder dump = new StringBuilder();