diff --git a/doc/src/sgml/release-9.4.sgml b/doc/src/sgml/release-9.4.sgml
index 7ae67e0cec..5330c425d3 100644
--- a/doc/src/sgml/release-9.4.sgml
+++ b/doc/src/sgml/release-9.4.sgml
@@ -120,7 +120,7 @@
 
     <listitem>
      <para>
-      When converting values of type <type>timestamp</>
+      When converting values of type <type>date</>, <type>timestamp</>
       or <type>timestamptz</>
       to <link linkend="datatype-json"><type>JSON</type></link>, render the
       values in a format compliant with ISO 8601 (Andrew Dunstan)
@@ -129,7 +129,10 @@
      <para>
       Previously such values were rendered according to the current
       <xref linkend="guc-datestyle"> setting; but many JSON processors
-      require timestamps to be in ISO 8601 format.
+      require timestamps to be in ISO 8601 format.  If necessary, the
+      previous behavior can be obtained by explicitly casting the datetime
+      value to <type>text</> before passing it to the JSON conversion
+      function.
      </para>
     </listitem>
 
diff --git a/src/backend/utils/adt/json.c b/src/backend/utils/adt/json.c
index 68132aea4b..494a028526 100644
--- a/src/backend/utils/adt/json.c
+++ b/src/backend/utils/adt/json.c
@@ -25,6 +25,7 @@
 #include "parser/parse_coerce.h"
 #include "utils/array.h"
 #include "utils/builtins.h"
+#include "utils/date.h"
 #include "utils/datetime.h"
 #include "utils/lsyscache.h"
 #include "utils/json.h"
@@ -55,8 +56,9 @@ typedef enum					/* type categories for datum_to_json */
 	JSONTYPE_NULL,				/* null, so we didn't bother to identify */
 	JSONTYPE_BOOL,				/* boolean (built-in types only) */
 	JSONTYPE_NUMERIC,			/* numeric (ditto) */
-	JSONTYPE_TIMESTAMP,         /* we use special formatting for timestamp */
-	JSONTYPE_TIMESTAMPTZ,       /* ... and timestamptz */
+	JSONTYPE_DATE,				/* we use special formatting for datetimes */
+	JSONTYPE_TIMESTAMP,
+	JSONTYPE_TIMESTAMPTZ,
 	JSONTYPE_JSON,				/* JSON itself (and JSONB) */
 	JSONTYPE_ARRAY,				/* array */
 	JSONTYPE_COMPOSITE,			/* composite */
@@ -1267,6 +1269,10 @@ json_categorize_type(Oid typoid,
 			*tcategory = JSONTYPE_NUMERIC;
 			break;
 
+		case DATEOID:
+			*tcategory = JSONTYPE_DATE;
+			break;
+
 		case TIMESTAMPOID:
 			*tcategory = JSONTYPE_TIMESTAMP;
 			break;
@@ -1348,7 +1354,7 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 		 tcategory == JSONTYPE_CAST))
 		ereport(ERROR,
 				(errcode(ERRCODE_INVALID_PARAMETER_VALUE),
-		  errmsg("key value must be scalar, not array, composite, or json")));
+		 errmsg("key value must be scalar, not array, composite, or json")));
 
 	switch (tcategory)
 	{
@@ -1388,6 +1394,30 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 			}
 			pfree(outputstr);
 			break;
+		case JSONTYPE_DATE:
+			{
+				DateADT		date;
+				struct pg_tm tm;
+				char		buf[MAXDATELEN + 1];
+
+				date = DatumGetDateADT(val);
+
+				/* XSD doesn't support infinite values */
+				if (DATE_NOT_FINITE(date))
+					ereport(ERROR,
+							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
+							 errmsg("date out of range"),
+							 errdetail("JSON does not support infinite date values.")));
+				else
+				{
+					j2date(date + POSTGRES_EPOCH_JDATE,
+						   &(tm.tm_year), &(tm.tm_mon), &(tm.tm_mday));
+					EncodeDateOnly(&tm, USE_XSD_DATES, buf);
+				}
+
+				appendStringInfo(result, "\"%s\"", buf);
+			}
+			break;
 		case JSONTYPE_TIMESTAMP:
 			{
 				Timestamp	timestamp;
@@ -1410,7 +1440,7 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
 
-				appendStringInfo(result,"\"%s\"",buf);
+				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_TIMESTAMPTZ:
@@ -1437,7 +1467,7 @@ datum_to_json(Datum val, bool is_null, StringInfo result,
 							(errcode(ERRCODE_DATETIME_VALUE_OUT_OF_RANGE),
 							 errmsg("timestamp out of range")));
 
-				appendStringInfo(result,"\"%s\"",buf);
+				appendStringInfo(result, "\"%s\"", buf);
 			}
 			break;
 		case JSONTYPE_JSON:
@@ -2305,20 +2335,21 @@ escape_json(StringInfo buf, const char *str)
 				appendStringInfoString(buf, "\\\"");
 				break;
 			case '\\':
+
 				/*
 				 * Unicode escapes are passed through as is. There is no
 				 * requirement that they denote a valid character in the
 				 * server encoding - indeed that is a big part of their
 				 * usefulness.
 				 *
-				 * All we require is that they consist of \uXXXX where
-				 * the Xs are hexadecimal digits. It is the responsibility
-				 * of the caller of, say, to_json() to make sure that the
-				 * unicode escape is valid.
+				 * All we require is that they consist of \uXXXX where the Xs
+				 * are hexadecimal digits. It is the responsibility of the
+				 * caller of, say, to_json() to make sure that the unicode
+				 * escape is valid.
 				 *
-				 * In the case of a jsonb string value being escaped, the
-				 * only unicode escape that should be present is \u0000,
-				 * all the other unicode escapes will have been resolved.
+				 * In the case of a jsonb string value being escaped, the only
+				 * unicode escape that should be present is \u0000, all the
+				 * other unicode escapes will have been resolved.
 				 */
 				if (p[1] == 'u' &&
 					isxdigit((unsigned char) p[2]) &&