diff --git a/CHANGES.txt b/CHANGES.txt
index 845c2b78bd..d9672ba542 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -34,6 +34,7 @@ Merged from 2.0:
  * Make sure high level sstables get compacted (CASSANDRA-7414)
  * Fix AssertionError when using empty clustering columns and static columns
    (CASSANDRA-7455)
+ * Add option to disable STCS in L0 (CASSANDRA-6621)
  * Upgrade to snappy-java 1.0.5.2 (CASSANDRA-7476)
 
 
diff --git a/NEWS.txt b/NEWS.txt
index 377296c27e..232cdf7e9d 100644
--- a/NEWS.txt
+++ b/NEWS.txt
@@ -80,6 +80,15 @@ Upgrading
    - support for supercolumns has been removed from json2sstable
 
 
+2.0.10
+====
+New features
+------------
+    - If you are using Leveled Compaction, you can now disable doing size-tiered
+      compaction in L0 by starting Cassandra with -Dcassandra.disable_stcs_in_l0
+      (see CASSANDRA-6621 for details).
+
+
 2.0.9
 =====
 
diff --git a/src/java/org/apache/cassandra/config/DatabaseDescriptor.java b/src/java/org/apache/cassandra/config/DatabaseDescriptor.java
index 9400705cc1..31f3bc622a 100644
--- a/src/java/org/apache/cassandra/config/DatabaseDescriptor.java
+++ b/src/java/org/apache/cassandra/config/DatabaseDescriptor.java
@@ -995,6 +995,11 @@ public class DatabaseDescriptor
         conf.compaction_throughput_mb_per_sec = value;
     }
 
+    public static boolean getDisableSTCSInL0()
+    {
+        return Boolean.getBoolean("cassandra.disable_stcs_in_l0");
+    }
+
     public static int getStreamThroughputOutboundMegabitsPerSec()
     {
         return conf.stream_throughput_outbound_megabits_per_sec;
diff --git a/src/java/org/apache/cassandra/db/compaction/LeveledManifest.java b/src/java/org/apache/cassandra/db/compaction/LeveledManifest.java
index aac57c0354..6ed21c8311 100644
--- a/src/java/org/apache/cassandra/db/compaction/LeveledManifest.java
+++ b/src/java/org/apache/cassandra/db/compaction/LeveledManifest.java
@@ -31,6 +31,9 @@ import com.google.common.primitives.Ints;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import org.apache.cassandra.config.CFMetaData;
+import org.apache.cassandra.config.DatabaseDescriptor;
+import org.apache.cassandra.config.Schema;
 import org.apache.cassandra.db.ColumnFamilyStore;
 import org.apache.cassandra.db.RowPosition;
 import org.apache.cassandra.dht.Bounds;
@@ -370,7 +373,7 @@ public class LeveledManifest
             if (score > 1.001)
             {
                 // before proceeding with a higher level, let's see if L0 is far enough behind to warrant STCS
-                if (getLevel(0).size() > MAX_COMPACTING_L0)
+                if (!DatabaseDescriptor.getDisableSTCSInL0() && getLevel(0).size() > MAX_COMPACTING_L0)
                 {
                     List<SSTableReader> mostInteresting = getSSTablesForSTCS(getLevel(0));
                     if (!mostInteresting.isEmpty())