diff --git a/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java b/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java
index 0fdcbf7bfb3c3..96159ec1b1feb 100644
--- a/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java
+++ b/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeExternalSorter.java
@@ -232,4 +232,4 @@ public UnsafeSorterIterator getSortedIterator() throws IOException {
     spillMerger.addSpill(sorter.getSortedIterator());
     return spillMerger.getSortedIterator();
   }
-}
\ No newline at end of file
+}
diff --git a/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterSpillMerger.java b/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterSpillMerger.java
index 94ee6699ef101..2fb41fb2d402f 100644
--- a/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterSpillMerger.java
+++ b/core/src/main/java/org/apache/spark/util/collection/unsafe/sort/UnsafeSorterSpillMerger.java
@@ -26,8 +26,8 @@ final class UnsafeSorterSpillMerger {
   private final PriorityQueue<UnsafeSorterIterator> priorityQueue;
 
   public UnsafeSorterSpillMerger(
-    final RecordComparator recordComparator,
-    final PrefixComparator prefixComparator) {
+      final RecordComparator recordComparator,
+      final PrefixComparator prefixComparator) {
     final Comparator<UnsafeSorterIterator> comparator = new Comparator<UnsafeSorterIterator>() {
 
       @Override
diff --git a/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/UnsafeSortMergeJoin.scala b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/UnsafeSortMergeJoin.scala
new file mode 100644
index 0000000000000..73a9bc6a2cf60
--- /dev/null
+++ b/sql/core/src/main/scala/org/apache/spark/sql/execution/joins/UnsafeSortMergeJoin.scala
@@ -0,0 +1,190 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.execution.joins
+
+import java.util.NoSuchElementException
+
+import org.apache.spark.annotation.DeveloperApi
+import org.apache.spark.rdd.RDD
+import org.apache.spark.sql.Row
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.catalyst.plans._
+import org.apache.spark.sql.catalyst.plans.physical._
+import org.apache.spark.sql.execution.{UnsafeExternalSort, BinaryNode, SparkPlan}
+import org.apache.spark.util.collection.CompactBuffer
+
+/**
+ * :: DeveloperApi ::
+ * Performs an sort merge join of two child relations.
+ * TODO(josh): Document
+ */
+@DeveloperApi
+case class UnsafeSortMergeJoin(
+    leftKeys: Seq[Expression],
+    rightKeys: Seq[Expression],
+    left: SparkPlan,
+    right: SparkPlan) extends BinaryNode {
+
+  override def output: Seq[Attribute] = left.output ++ right.output
+
+  override def outputPartitioning: Partitioning = left.outputPartitioning
+
+  override def requiredChildDistribution: Seq[Distribution] =
+    ClusteredDistribution(leftKeys) :: ClusteredDistribution(rightKeys) :: Nil
+
+  // this is to manually construct an ordering that can be used to compare keys from both sides
+  private val keyOrdering: RowOrdering = RowOrdering.forSchema(leftKeys.map(_.dataType))
+
+  override def outputOrdering: Seq[SortOrder] = requiredOrders(leftKeys)
+
+  @transient protected lazy val leftKeyGenerator = newProjection(leftKeys, left.output)
+  @transient protected lazy val rightKeyGenerator = newProjection(rightKeys, right.output)
+
+  private def requiredOrders(keys: Seq[Expression]): Seq[SortOrder] =
+    keys.map(SortOrder(_, Ascending))
+
+  protected override def doExecute(): RDD[Row] = {
+    // Note that we purposely do not require out input to be sorted. Instead, we'll sort it
+    // ourselves using UnsafeExternalSorter. Not requiring the input to be sorted will prevent the
+    // Exchange from pushing the sort into the shuffle, which will allow the shuffle to benefit from
+    // Project Tungsten's shuffle optimizations which currently cannot be applied to shuffles that
+    // specify a key ordering.
+
+    // Only sort if necessary:
+    val leftOrder = requiredOrders(leftKeys)
+    val leftResults = {
+      if (left.outputOrdering == leftOrder) {
+        left.execute().map(_.copy())
+      } else {
+        new UnsafeExternalSort(leftOrder, global = false, left).execute()
+      }
+    }
+    val rightOrder = requiredOrders(rightKeys)
+    val rightResults = {
+      if (right.outputOrdering == rightOrder) {
+        right.execute().map(_.copy())
+      } else {
+        new UnsafeExternalSort(rightOrder, global = false, right).execute()
+      }
+    }
+
+    leftResults.zipPartitions(rightResults) { (leftIter, rightIter) =>
+      new Iterator[Row] {
+        // Mutable per row objects.
+        private[this] val joinRow = new JoinedRow5
+        private[this] var leftElement: Row = _
+        private[this] var rightElement: Row = _
+        private[this] var leftKey: Row = _
+        private[this] var rightKey: Row = _
+        private[this] var rightMatches: CompactBuffer[Row] = _
+        private[this] var rightPosition: Int = -1
+        private[this] var stop: Boolean = false
+        private[this] var matchKey: Row = _
+
+        // initialize iterator
+        initialize()
+
+        override final def hasNext: Boolean = nextMatchingPair()
+
+        override final def next(): Row = {
+          if (hasNext) {
+            // we are using the buffered right rows and run down left iterator
+            val joinedRow = joinRow(leftElement, rightMatches(rightPosition))
+            rightPosition += 1
+            if (rightPosition >= rightMatches.size) {
+              rightPosition = 0
+              fetchLeft()
+              if (leftElement == null || keyOrdering.compare(leftKey, matchKey) != 0) {
+                stop = false
+                rightMatches = null
+              }
+            }
+            joinedRow
+          } else {
+            // no more result
+            throw new NoSuchElementException
+          }
+        }
+
+        private def fetchLeft() = {
+          if (leftIter.hasNext) {
+            leftElement = leftIter.next()
+            println(leftElement)
+            leftKey = leftKeyGenerator(leftElement)
+          } else {
+            leftElement = null
+          }
+        }
+
+        private def fetchRight() = {
+          if (rightIter.hasNext) {
+            rightElement = rightIter.next()
+            println(right)
+            rightKey = rightKeyGenerator(rightElement)
+          } else {
+            rightElement = null
+          }
+        }
+
+        private def initialize() = {
+          fetchLeft()
+          fetchRight()
+        }
+
+        /**
+         * Searches the right iterator for the next rows that have matches in left side, and store
+         * them in a buffer.
+         *
+         * @return true if the search is successful, and false if the right iterator runs out of
+         *         tuples.
+         */
+        private def nextMatchingPair(): Boolean = {
+          if (!stop && rightElement != null) {
+            // run both side to get the first match pair
+            while (!stop && leftElement != null && rightElement != null) {
+              val comparing = keyOrdering.compare(leftKey, rightKey)
+              // for inner join, we need to filter those null keys
+              stop = comparing == 0 && !leftKey.anyNull
+              if (comparing > 0 || rightKey.anyNull) {
+                fetchRight()
+              } else if (comparing < 0 || leftKey.anyNull) {
+                fetchLeft()
+              }
+            }
+            rightMatches = new CompactBuffer[Row]()
+            if (stop) {
+              stop = false
+              // iterate the right side to buffer all rows that matches
+              // as the records should be ordered, exit when we meet the first that not match
+              while (!stop && rightElement != null) {
+                rightMatches += rightElement
+                fetchRight()
+                stop = keyOrdering.compare(leftKey, rightKey) != 0
+              }
+              if (rightMatches.size > 0) {
+                rightPosition = 0
+                matchKey = leftKey
+              }
+            }
+          }
+          rightMatches != null && rightMatches.size > 0
+        }
+      }
+    }
+  }
+}
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/UnsafeSortMergeJoinSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/UnsafeSortMergeJoinSuite.scala
new file mode 100644
index 0000000000000..4ce0537f02418
--- /dev/null
+++ b/sql/core/src/test/scala/org/apache/spark/sql/UnsafeSortMergeJoinSuite.scala
@@ -0,0 +1,52 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql
+
+import org.apache.spark.sql.TestData._
+import org.apache.spark.sql.execution.UnsafeExternalSort
+import org.apache.spark.sql.execution.joins._
+import org.apache.spark.sql.test.TestSQLContext._
+import org.apache.spark.sql.test.TestSQLContext.implicits._
+import org.scalatest.BeforeAndAfterEach
+
+class UnsafeSortMergeJoinSuite extends QueryTest with BeforeAndAfterEach {
+  // Ensures tables are loaded.
+  TestData
+
+  conf.setConf(SQLConf.SORTMERGE_JOIN, "true")
+  conf.setConf(SQLConf.CODEGEN_ENABLED, "true")
+  conf.setConf(SQLConf.UNSAFE_ENABLED, "true")
+  conf.setConf(SQLConf.EXTERNAL_SORT, "true")
+  conf.setConf(SQLConf.AUTO_BROADCASTJOIN_THRESHOLD, "-1")
+
+  test("basic sort merge join test") {
+    val df = upperCaseData.join(lowerCaseData, $"n" === $"N")
+    print(df.queryExecution.optimizedPlan)
+    assert(df.queryExecution.sparkPlan.collect {
+      case smj: UnsafeSortMergeJoin => smj
+    }.nonEmpty)
+    checkAnswer(
+      df,
+      Seq(
+        Row(1, "A", 1, "a"),
+        Row(2, "B", 2, "b"),
+        Row(3, "C", 3, "c"),
+        Row(4, "D", 4, "d")
+      ))
+  }
+}
diff --git a/sql/core/src/test/scala/org/apache/spark/sql/execution/UnsafeExternalSortSuite.scala b/sql/core/src/test/scala/org/apache/spark/sql/execution/UnsafeExternalSortSuite.scala
new file mode 100644
index 0000000000000..f5a6368a2b16a
--- /dev/null
+++ b/sql/core/src/test/scala/org/apache/spark/sql/execution/UnsafeExternalSortSuite.scala
@@ -0,0 +1,62 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.execution
+
+import org.apache.spark.sql.catalyst.CatalystTypeConverters
+import org.scalatest.{FunSuite, Matchers}
+
+import org.apache.spark.sql.{SQLConf, SQLContext, Row}
+import org.apache.spark.sql.catalyst.expressions._
+import org.apache.spark.sql.types._
+import org.apache.spark.sql.test.TestSQLContext
+import org.apache.spark.sql.test.TestSQLContext.implicits._
+
+class UnsafeExternalSortSuite extends FunSuite with Matchers {
+
+  private def createRow(values: Any*): Row = {
+    new GenericRow(values.map(CatalystTypeConverters.convertToCatalyst).toArray)
+  }
+
+  test("basic sorting") {
+    val sc = TestSQLContext.sparkContext
+    val sqlContext = new SQLContext(sc)
+    sqlContext.conf.setConf(SQLConf.CODEGEN_ENABLED, "true")
+
+    val schema: StructType = StructType(
+      StructField("word", StringType, nullable = false) ::
+      StructField("number", IntegerType, nullable = false) :: Nil)
+    val sortOrder: Seq[SortOrder] = Seq(
+      SortOrder(BoundReference(0, StringType, nullable = false), Ascending),
+      SortOrder(BoundReference(1, IntegerType, nullable = false), Descending))
+    val rowsToSort: Seq[Row] = Seq(
+      createRow("Hello", 9),
+      createRow("World", 4),
+      createRow("Hello", 7),
+      createRow("Skinny", 0),
+      createRow("Constantinople", 9))
+    SparkPlan.currentContext.set(sqlContext)
+    val input =
+      new PhysicalRDD(schema.toAttributes.map(_.toAttribute), sc.parallelize(rowsToSort, 1))
+    // Treat the existing sort operators as the source-of-truth for this test
+    val defaultSorted = new Sort(sortOrder, global = false, input).executeCollect()
+    val externalSorted = new ExternalSort(sortOrder, global = false, input).executeCollect()
+    val unsafeSorted = new UnsafeExternalSort(sortOrder, global = false, input).executeCollect()
+    assert (defaultSorted === externalSorted)
+    assert (unsafeSorted === externalSorted)
+  }
+}
diff --git a/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/UnsafeSortMergeCompatibiltySuite.scala b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/UnsafeSortMergeCompatibiltySuite.scala
new file mode 100644
index 0000000000000..093ce3504e2c2
--- /dev/null
+++ b/sql/hive/compatibility/src/test/scala/org/apache/spark/sql/hive/execution/UnsafeSortMergeCompatibiltySuite.scala
@@ -0,0 +1,41 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF licenses this file to You under the Apache License, Version 2.0
+ * (the "License"); you may not use this file except in compliance with
+ * the License.  You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+package org.apache.spark.sql.hive.execution
+
+import org.apache.spark.sql.SQLConf
+import org.apache.spark.sql.hive.test.TestHive
+
+/**
+ * Runs the test cases that are included in the hive distribution with sort merge join and
+ * unsafe external sort enabled.
+ */
+class UnsafeSortMergeCompatibiltySuite extends SortMergeCompatibilitySuite {
+  override def beforeAll() {
+    super.beforeAll()
+    TestHive.setConf(SQLConf.CODEGEN_ENABLED, "true")
+    TestHive.setConf(SQLConf.UNSAFE_ENABLED, "true")
+    TestHive.setConf(SQLConf.EXTERNAL_SORT, "true")
+  }
+
+  override def afterAll() {
+    TestHive.setConf(SQLConf.CODEGEN_ENABLED, "false")
+    TestHive.setConf(SQLConf.UNSAFE_ENABLED, "false")
+    TestHive.setConf(SQLConf.EXTERNAL_SORT, "false")
+    super.afterAll()
+  }
+}
\ No newline at end of file