diff --git a/CHANGES.txt b/CHANGES.txt
index 5168acb46268..a6bc9d9d005b 100644
--- a/CHANGES.txt
+++ b/CHANGES.txt
@@ -2,6 +2,7 @@
  * Fix short read protection for GROUP BY queries (CASSANDRA-15459)
  * 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)
  * stop_paranoid disk failure policy is ignored on CorruptSSTableException after node is up (CASSANDRA-15191)
diff --git a/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java b/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java
index a820a899fffb..c5de4446f0c0 100644
--- a/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java
+++ b/src/java/org/apache/cassandra/db/SinglePartitionReadCommand.java
@@ -919,7 +919,6 @@ private UnfilteredRowIterator queryMemtableAndSSTablesInTimestampOrder(ColumnFam
 
         /* 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)
@@ -993,9 +992,6 @@ private UnfilteredRowIterator queryMemtableAndSSTablesInTimestampOrder(ColumnFam
                 if (iter.isEmpty())
                     continue;
 
-                if (sstable.isRepaired())
-                    onlyUnrepaired = false;
-
                 result = add(
                     RTBoundValidator.validate(isForThrift() ? ThriftResultsMerger.maybeWrap(iter, nowInSec()) : iter, RTBoundValidator.Stage.SSTABLE, false),
                     result,
@@ -1014,26 +1010,6 @@ private UnfilteredRowIterator queryMemtableAndSSTablesInTimestampOrder(ColumnFam
         cfs.metric.samplers.get(TableMetrics.Sampler.READS).addSample(key.getKey(), key.hashCode(), 1);
         StorageHook.instance.reportRead(cfs.metadata.cfId, 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()));
-                StageManager.getStage(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 5d431432edf5..3a5e9aa92b0b 100644
--- a/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java
+++ b/src/java/org/apache/cassandra/db/compaction/AbstractCompactionStrategy.java
@@ -304,11 +304,6 @@ public ScannerList getScanners(Collection<SSTableReader> sstables, Collection<Ra
         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 86170a1050bb..d48667944a01 100644
--- a/src/java/org/apache/cassandra/db/compaction/CompactionStrategyManager.java
+++ b/src/java/org/apache/cassandra/db/compaction/CompactionStrategyManager.java
@@ -104,7 +104,6 @@ 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;
 
@@ -216,7 +215,6 @@ private void startup()
             }
             repaired.forEach(AbstractCompactionStrategy::startup);
             unrepaired.forEach(AbstractCompactionStrategy::startup);
-            shouldDefragment = repaired.get(0).shouldDefragment();
             supportsEarlyOpen = repaired.get(0).supportsEarlyOpen();
             fanout = (repaired.get(0) instanceof LeveledCompactionStrategy) ? ((LeveledCompactionStrategy) repaired.get(0)).getLevelFanoutSize() : LeveledCompactionStrategy.DEFAULT_LEVEL_FANOUT_SIZE;
         }
@@ -472,11 +470,6 @@ else if (i < a.length)
         return res;
     }
 
-    public boolean shouldDefragment()
-    {
-        return shouldDefragment;
-    }
-
     public Directories getDirectories()
     {
         maybeReloadDiskBoundaries();
diff --git a/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java b/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java
index 01b918192371..048803a66d4b 100644
--- a/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java
+++ b/src/java/org/apache/cassandra/db/compaction/SizeTieredCompactionStrategy.java
@@ -322,12 +322,6 @@ public static Map<String, String> validateOptions(Map<String, String> options) t
         return uncheckedOptions;
     }
 
-    @Override
-    public boolean shouldDefragment()
-    {
-        return true;
-    }
-
     @Override
     public synchronized void addSSTable(SSTableReader added)
     {