diff --git a/CHANGES.txt b/CHANGES.txt
index 58239c9de9..7298e0c643 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -12,6 +12,7 @@ Merged from 3.11:
  * stop_paranoid disk failure policy is ignored on CorruptSSTableException after node is up (CASSANDRA-15191)
  * Frozen RawTuple is not annotated with frozen in the toString method (CASSANDRA-15857)
 Merged from 3.0:
+ * Remove broken 'defrag-on-read' optimization (CASSANDRA-15432)
  * Check for endpoint collision with hibernating nodes (CASSANDRA-14599)
  * Operational improvements and hardening for replica filtering protection (CASSANDRA-15907)
  * Fix empty/null json string representation (CASSANDRA-15896)
diff --git a/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java b/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java
index 6fbe52314a..e581be56df 100644
--- a/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java
+++ b/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java
@@ -28,7 +28,6 @@ import com.google.common.collect.Sets;
 import org.apache.cassandra.cache.IRowCacheEntry;
 import org.apache.cassandra.cache.RowCacheKey;
 import org.apache.cassandra.cache.RowCacheSentinel;
-import org.apache.cassandra.concurrent.Stage;
 import org.apache.cassandra.config.DatabaseDescriptor;
 import org.apache.cassandra.db.filter.*;
 import org.apache.cassandra.db.lifecycle.*;
@@ -817,7 +816,6 @@ public class SinglePartitionReadCommand extends ReadCommand implements SinglePar
 
         /* add the SSTables on disk */
         Collections.sort(view.sstables, SSTableReader.maxTimestampDescending);
-        boolean onlyUnrepaired = true;
         // read sorted sstables
         SSTableReadMetricsCollector metricsCollector = new SSTableReadMetricsCollector();
         for (SSTableReader sstable : view.sstables)
@@ -889,9 +887,6 @@ public class SinglePartitionReadCommand extends ReadCommand implements SinglePar
                 if (iter.isEmpty())
                     continue;
 
-                if (sstable.isRepaired())
-                    onlyUnrepaired = false;
-
                 result = add(
                     RTBoundValidator.validate(iter, RTBoundValidator.Stage.SSTABLE, false),
                     result,
@@ -910,26 +905,6 @@ public class SinglePartitionReadCommand extends ReadCommand implements SinglePar
         cfs.metric.topReadPartitionFrequency.addSample(key.getKey(), 1);
         StorageHook.instance.reportRead(cfs.metadata.id, partitionKey());
 
-        // "hoist up" the requested data into a more recent sstable
-        if (metricsCollector.getMergedSSTables() > cfs.getMinimumCompactionThreshold()
-            && onlyUnrepaired
-            && !cfs.isAutoCompactionDisabled()
-            && cfs.getCompactionStrategyManager().shouldDefragment())
-        {
-            // !!WARNING!!   if we stop copying our data to a heap-managed object,
-            //               we will need to track the lifetime of this mutation as well
-            Tracing.trace("Defragmenting requested data");
-
-            try (UnfilteredRowIterator iter = result.unfilteredIterator(columnFilter(), Slices.ALL, false))
-            {
-                final Mutation mutation = new Mutation(PartitionUpdate.fromIterator(iter, columnFilter()));
-                Stage.MUTATION.execute(() -> {
-                    // skipping commitlog and index updates is fine since we're just de-fragmenting existing data
-                    Keyspace.open(mutation.getKeyspaceName()).apply(mutation, false, false);
-                });
-            }
-        }
-
         return result.unfilteredIterator(columnFilter(), Slices.ALL, clusteringIndexFilter().isReversed());
     }
 
diff --git a/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java b/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java
index 1e72ae55ff..c764d6e5d1 100644
--- a/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java
+++ b/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java
@@ -252,11 +252,6 @@ public abstract class AbstractCompactionStrategy
         return new ScannerList(scanners);
     }
 
-    public boolean shouldDefragment()
-    {
-        return false;
-    }
-
     public String getName()
     {
         return getClass().getSimpleName();
diff --git a/src/java/org/apache/cassandra/db/compaction/CompactionStrategyManager.java b/src/java/org/apache/cassandra/db/compaction/CompactionStrategyManager.java
index 546f61b445..708faff44a 100644
--- a/src/java/org/apache/cassandra/db/compaction/CompactionStrategyManager.java
+++ b/src/java/org/apache/cassandra/db/compaction/CompactionStrategyManager.java
@@ -134,7 +134,6 @@ public class CompactionStrategyManager implements INotificationConsumer
         we will use the new compaction parameters.
      */
     private volatile CompactionParams schemaCompactionParams;
-    private boolean shouldDefragment;
     private boolean supportsEarlyOpen;
     private int fanout;
 
@@ -309,7 +308,6 @@ public class CompactionStrategyManager implements INotificationConsumer
                     compactionStrategyFor(sstable).addSSTable(sstable);
             }
             holders.forEach(AbstractStrategyHolder::startup);
-            shouldDefragment = repaired.first().shouldDefragment();
             supportsEarlyOpen = repaired.first().supportsEarlyOpen();
             fanout = (repaired.first() instanceof LeveledCompactionStrategy) ? ((LeveledCompactionStrategy) repaired.first()).getLevelFanoutSize() : LeveledCompactionStrategy.DEFAULT_LEVEL_FANOUT_SIZE;
         }
@@ -600,11 +598,6 @@ public class CompactionStrategyManager implements INotificationConsumer
         return res;
     }
 
-    public boolean shouldDefragment()
-    {
-        return shouldDefragment;
-    }
-
     private void handleFlushNotification(Iterable<SSTableReader> added)
     {
         // If reloaded, SSTables will be placed in their correct locations
diff --git a/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java b/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java
index a79299e1b4..8d1d8dac2e 100644
--- a/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java
+++ b/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java
@@ -323,12 +323,6 @@ public class SizeTieredCompactionStrategy extends AbstractCompactionStrategy
         return uncheckedOptions;
     }
 
-    @Override
-    public boolean shouldDefragment()
-    {
-        return true;
-    }
-
     @Override
     public synchronized void addSSTable(SSTableReader added)
     {