diff --git a/presto-docs/src/main/sphinx/functions/array.rst b/presto-docs/src/main/sphinx/functions/array.rst
index 767d2acae0e58..98e4b6e346a3e 100644
--- a/presto-docs/src/main/sphinx/functions/array.rst
+++ b/presto-docs/src/main/sphinx/functions/array.rst
@@ -48,6 +48,16 @@ Array Functions
 
     Returns an array of elements in ``x`` but not in ``y``, without duplicates.
 
+.. function:: array_frequency(array(bigint)) -> map(bigint, int)
+
+    Returns a map: keys are the unique elements in the ``array``, values are how many times the key appears.
+    Ignores null elements. Empty array returns empty map.
+
+.. function:: array_frequency(array(varchar)) -> map(varchar, int)
+
+    Returns a map: keys are the unique elements in the ``array``, values are how many times the key appears.
+    Ignores null elements. Empty array returns empty map.
+
 .. function:: array_intersect(x, y) -> array
 
     Returns an array of the elements in the intersection of ``x`` and ``y``, without duplicates.
diff --git a/presto-main/src/main/java/com/facebook/presto/operator/scalar/sql/ArrayArithmeticFunctions.java b/presto-main/src/main/java/com/facebook/presto/operator/scalar/sql/ArrayArithmeticFunctions.java
index aeb6d7daf74fc..be61800bc9bcb 100644
--- a/presto-main/src/main/java/com/facebook/presto/operator/scalar/sql/ArrayArithmeticFunctions.java
+++ b/presto-main/src/main/java/com/facebook/presto/operator/scalar/sql/ArrayArithmeticFunctions.java
@@ -52,4 +52,30 @@ public static String arrayAverage()
                 "(s, x) -> IF(x IS NOT NULL, (s[1] + x, s[2] + 1), s), " +
                 "s -> if(s[2] = 0, cast(null as double), s[1] / cast(s[2] as double)))";
     }
+
+    @SqlInvokedScalarFunction(value = "array_frequency", deterministic = true, calledOnNullInput = false)
+    @Description("Returns the frequency of all array elements as a map.")
+    @SqlParameter(name = "input", type = "array(bigint)")
+    @SqlType("map(bigint, int)")
+    public static String arrayFrequencyBigint()
+    {
+        return "RETURN reduce(" +
+                "input," +
+                "MAP()," +
+                "(m, x) -> IF (x IS NOT NULL, MAP_CONCAT(m,MAP_FROM_ENTRIES(ARRAY[ROW(x, COALESCE(ELEMENT_AT(m,x) + 1, 1))])), m)," +
+                "m -> m)";
+    }
+
+    @SqlInvokedScalarFunction(value = "array_frequency", deterministic = true, calledOnNullInput = false)
+    @Description("Returns the frequency of all array elements as a map.")
+    @SqlParameter(name = "input", type = "array(varchar)")
+    @SqlType("map(varchar, int)")
+    public static String arrayFrequencyVarchar()
+    {
+        return "RETURN reduce(" +
+                "input," +
+                "MAP()," +
+                "(m, x) -> IF (x IS NOT NULL, MAP_CONCAT(m,MAP_FROM_ENTRIES(ARRAY[ROW(x, COALESCE(ELEMENT_AT(m,x) + 1, 1))])), m)," +
+                "m -> m)";
+    }
 }
diff --git a/presto-main/src/test/java/com/facebook/presto/operator/scalar/sql/TestArrayArithmeticFunctions.java b/presto-main/src/test/java/com/facebook/presto/operator/scalar/sql/TestArrayArithmeticFunctions.java
index c017d3c532123..35e60c61e10f9 100644
--- a/presto-main/src/test/java/com/facebook/presto/operator/scalar/sql/TestArrayArithmeticFunctions.java
+++ b/presto-main/src/test/java/com/facebook/presto/operator/scalar/sql/TestArrayArithmeticFunctions.java
@@ -13,11 +13,20 @@
  */
 package com.facebook.presto.operator.scalar.sql;
 
+import com.facebook.presto.common.type.MapType;
+import com.facebook.presto.common.type.TestRowType;
+import com.facebook.presto.common.type.TypeSignature;
+import com.facebook.presto.metadata.FunctionAndTypeManager;
 import com.facebook.presto.operator.scalar.AbstractTestFunctions;
+import com.google.common.collect.ImmutableMap;
 import org.testng.annotations.Test;
 
+import static com.facebook.presto.common.block.MethodHandleUtil.methodHandle;
 import static com.facebook.presto.common.type.BigintType.BIGINT;
 import static com.facebook.presto.common.type.DoubleType.DOUBLE;
+import static com.facebook.presto.common.type.IntegerType.INTEGER;
+import static com.facebook.presto.common.type.VarcharType.VARCHAR;
+import static com.facebook.presto.metadata.FunctionAndTypeManager.createTestFunctionAndTypeManager;
 
 public class TestArrayArithmeticFunctions
         extends AbstractTestFunctions
@@ -65,4 +74,51 @@ public void testArrayAverage()
         assertFunction("array_average(array[null, null])", DOUBLE, null);
         assertFunction("array_average(null)", DOUBLE, null);
     }
+
+    @Test
+    public void testArrayFrequencyBigint()
+    {
+        FunctionAndTypeManager functionAndTypeManager = createTestFunctionAndTypeManager();
+        MapType type = new MapType(BIGINT,
+                INTEGER,
+                methodHandle(TestRowType.class, "throwUnsupportedOperation"),
+                methodHandle(TestRowType.class, "throwUnsupportedOperation"));
+        TypeSignature typeSignature = TypeSignature.parseTypeSignature(type.getDisplayName());
+
+        assertFunction("array_frequency(cast(null as array(bigint)))", functionAndTypeManager.getType(typeSignature), null);
+        assertFunction("array_frequency(cast(array[] as array(bigint)))", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
+        assertFunction("array_frequency(array[cast(null as bigint), cast(null as bigint), cast(null as bigint)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
+        assertFunction("array_frequency(array[cast(null as bigint), bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 1));
+        assertFunction("array_frequency(array[cast(null as bigint), bigint '1', bigint '3', cast(null as bigint), bigint '1', bigint '3', cast(null as bigint)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 3L, 2));
+        assertFunction("array_frequency(array[bigint '1', bigint '1', bigint '2', bigint '2', bigint '3', bigint '1', bigint '3', bigint '2'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 3, 2L, 3, 3L, 2));
+        assertFunction("array_frequency(array[bigint '45'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(45L, 1));
+        assertFunction("array_frequency(array[bigint '-45'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(-45L, 1));
+        assertFunction("array_frequency(array[bigint '1', bigint '3', bigint '1', bigint '3'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 3L, 2));
+        assertFunction("array_frequency(array[bigint '3', bigint '1', bigint '3',bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 3L, 2));
+        assertFunction("array_frequency(array[bigint '4',bigint '3',bigint '3',bigint '2',bigint '2',bigint '2',bigint '1',bigint '1',bigint '1',bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 4, 2L, 3, 3L, 2, 4L, 1));
+        assertFunction("array_frequency(array[bigint '3', bigint '3', bigint '2', bigint '2', bigint '5', bigint '5', bigint '1', bigint '1'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of(1L, 2, 2L, 2, 3L, 2, 5L, 2));
+    }
+
+    @Test
+    public void testArrayFrequencyVarchar()
+    {
+        FunctionAndTypeManager functionAndTypeManager = createTestFunctionAndTypeManager();
+
+        MapType type = new MapType(VARCHAR,
+                INTEGER,
+                methodHandle(TestRowType.class, "throwUnsupportedOperation"),
+                methodHandle(TestRowType.class, "throwUnsupportedOperation"));
+        TypeSignature typeSignature = TypeSignature.parseTypeSignature(type.getDisplayName());
+
+        assertFunction("array_frequency(cast(null as array(varchar)))", functionAndTypeManager.getType(typeSignature), null);
+        assertFunction("array_frequency(cast(array[] as array(varchar)))", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
+        assertFunction("array_frequency(array[cast(null as varchar), cast(null as varchar), cast(null as varchar)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of());
+        assertFunction("array_frequency(array[varchar 'z', cast(null as varchar)])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("z", 1));
+        assertFunction("array_frequency(array[varchar 'a', cast(null as varchar), varchar 'b', cast(null as varchar), cast(null as varchar) ])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("a", 1, "b", 1));
+        assertFunction("array_frequency(array[varchar 'a', varchar 'b', varchar 'a', varchar 'a', varchar 'a'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("a", 4, "b", 1));
+        assertFunction("array_frequency(array[varchar 'a', varchar 'b', varchar 'a', varchar 'b', varchar 'c'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("a", 2, "b", 2, "c", 1));
+        assertFunction("array_frequency(array[varchar 'y', varchar 'p'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("p", 1, "y", 1));
+        assertFunction("array_frequency(array[varchar 'a', varchar 'a', varchar 'p'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("p", 1, "a", 2));
+        assertFunction("array_frequency(array[varchar 'z'])", functionAndTypeManager.getType(typeSignature), ImmutableMap.of("z", 1));
+    }
 }