diff --git a/contrib/postgres_fdw/deparse.c b/contrib/postgres_fdw/deparse.c
index 8f09cd51ca..dd25699d83 100644
--- a/contrib/postgres_fdw/deparse.c
+++ b/contrib/postgres_fdw/deparse.c
@@ -1806,10 +1806,27 @@ deparseNullTest(NullTest *node, deparse_expr_cxt *context)
 
 	appendStringInfoChar(buf, '(');
 	deparseExpr(node->arg, context);
-	if (node->nulltesttype == IS_NULL)
-		appendStringInfoString(buf, " IS NULL)");
+
+	/*
+	 * For scalar inputs, we prefer to print as IS [NOT] NULL, which is
+	 * shorter and traditional.  If it's a rowtype input but we're applying a
+	 * scalar test, must print IS [NOT] DISTINCT FROM NULL to be semantically
+	 * correct.
+	 */
+	if (node->argisrow || !type_is_rowtype(exprType((Node *) node->arg)))
+	{
+		if (node->nulltesttype == IS_NULL)
+			appendStringInfoString(buf, " IS NULL)");
+		else
+			appendStringInfoString(buf, " IS NOT NULL)");
+	}
 	else
-		appendStringInfoString(buf, " IS NOT NULL)");
+	{
+		if (node->nulltesttype == IS_NULL)
+			appendStringInfoString(buf, " IS NOT DISTINCT FROM NULL)");
+		else
+			appendStringInfoString(buf, " IS DISTINCT FROM NULL)");
+	}
 }
 
 /*
diff --git a/src/backend/optimizer/util/plancat.c b/src/backend/optimizer/util/plancat.c
index 2be0793cc0..f037f90d98 100644
--- a/src/backend/optimizer/util/plancat.c
+++ b/src/backend/optimizer/util/plancat.c
@@ -1090,7 +1090,13 @@ get_relation_constraints(PlannerInfo *root,
 												  att->attcollation,
 												  0);
 					ntest->nulltesttype = IS_NOT_NULL;
-					ntest->argisrow = type_is_rowtype(att->atttypid);
+
+					/*
+					 * argisrow=false is correct even for a composite column,
+					 * because attnotnull does not represent a SQL-spec IS NOT
+					 * NULL test in such a case, just IS DISTINCT FROM NULL.
+					 */
+					ntest->argisrow = false;
 					ntest->location = -1;
 					result = lappend(result, ntest);
 				}
diff --git a/src/backend/utils/adt/ruleutils.c b/src/backend/utils/adt/ruleutils.c
index 97bdccf6ec..8a6d0ad966 100644
--- a/src/backend/utils/adt/ruleutils.c
+++ b/src/backend/utils/adt/ruleutils.c
@@ -7890,17 +7890,43 @@ get_rule_expr(Node *node, deparse_context *context,
 				if (!PRETTY_PAREN(context))
 					appendStringInfoChar(buf, '(');
 				get_rule_expr_paren((Node *) ntest->arg, context, true, node);
-				switch (ntest->nulltesttype)
+
+				/*
+				 * For scalar inputs, we prefer to print as IS [NOT] NULL,
+				 * which is shorter and traditional.  If it's a rowtype input
+				 * but we're applying a scalar test, must print IS [NOT]
+				 * DISTINCT FROM NULL to be semantically correct.
+				 */
+				if (ntest->argisrow ||
+					!type_is_rowtype(exprType((Node *) ntest->arg)))
 				{
-					case IS_NULL:
-						appendStringInfoString(buf, " IS NULL");
-						break;
-					case IS_NOT_NULL:
-						appendStringInfoString(buf, " IS NOT NULL");
-						break;
-					default:
-						elog(ERROR, "unrecognized nulltesttype: %d",
-							 (int) ntest->nulltesttype);
+					switch (ntest->nulltesttype)
+					{
+						case IS_NULL:
+							appendStringInfoString(buf, " IS NULL");
+							break;
+						case IS_NOT_NULL:
+							appendStringInfoString(buf, " IS NOT NULL");
+							break;
+						default:
+							elog(ERROR, "unrecognized nulltesttype: %d",
+								 (int) ntest->nulltesttype);
+					}
+				}
+				else
+				{
+					switch (ntest->nulltesttype)
+					{
+						case IS_NULL:
+							appendStringInfoString(buf, " IS NOT DISTINCT FROM NULL");
+							break;
+						case IS_NOT_NULL:
+							appendStringInfoString(buf, " IS DISTINCT FROM NULL");
+							break;
+						default:
+							elog(ERROR, "unrecognized nulltesttype: %d",
+								 (int) ntest->nulltesttype);
+					}
 				}
 				if (!PRETTY_PAREN(context))
 					appendStringInfoChar(buf, ')');
diff --git a/src/include/nodes/primnodes.h b/src/include/nodes/primnodes.h
index c8b1f907a8..a8a2c4e4e7 100644
--- a/src/include/nodes/primnodes.h
+++ b/src/include/nodes/primnodes.h
@@ -1076,8 +1076,16 @@ typedef struct XmlExpr
  * NullTest represents the operation of testing a value for NULLness.
  * The appropriate test is performed and returned as a boolean Datum.
  *
- * NOTE: the semantics of this for rowtype inputs are noticeably different
- * from the scalar case.  We provide an "argisrow" flag to reflect that.
+ * When argisrow is false, this simply represents a test for the null value.
+ *
+ * When argisrow is true, the input expression must yield a rowtype, and
+ * the node implements "row IS [NOT] NULL" per the SQL standard.  This
+ * includes checking individual fields for NULLness when the row datum
+ * itself isn't NULL.
+ *
+ * NOTE: the combination of a rowtype input and argisrow==false does NOT
+ * correspond to the SQL notation "row IS [NOT] NULL"; instead, this case
+ * represents the SQL notation "row IS [NOT] DISTINCT FROM NULL".
  * ----------------
  */
 
@@ -1091,7 +1099,7 @@ typedef struct NullTest
 	Expr		xpr;
 	Expr	   *arg;			/* input expression */
 	NullTestType nulltesttype;	/* IS NULL, IS NOT NULL */
-	bool		argisrow;		/* T if input is of a composite type */
+	bool		argisrow;		/* T to perform field-by-field null checks */
 	int			location;		/* token location, or -1 if unknown */
 } NullTest;
 
diff --git a/src/test/regress/expected/rowtypes.out b/src/test/regress/expected/rowtypes.out
index 2971640b4b..25b08281c8 100644
--- a/src/test/regress/expected/rowtypes.out
+++ b/src/test/regress/expected/rowtypes.out
@@ -664,10 +664,10 @@ explain (verbose, costs off)
 select r, r is null as isnull, r is not null as isnotnull
 from (values (1,row(1,2)), (1,row(null,null)), (1,null),
              (null,row(1,2)), (null,row(null,null)), (null,null) ) r(a,b);
-                                                                                           QUERY PLAN                                                                                            
--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
+                                                                                                         QUERY PLAN                                                                                                          
+-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
  Values Scan on "*VALUES*"
-   Output: ROW("*VALUES*".column1, "*VALUES*".column2), (("*VALUES*".column1 IS NULL) AND ("*VALUES*".column2 IS NULL)), (("*VALUES*".column1 IS NOT NULL) AND ("*VALUES*".column2 IS NOT NULL))
+   Output: ROW("*VALUES*".column1, "*VALUES*".column2), (("*VALUES*".column1 IS NULL) AND ("*VALUES*".column2 IS NOT DISTINCT FROM NULL)), (("*VALUES*".column1 IS NOT NULL) AND ("*VALUES*".column2 IS DISTINCT FROM NULL))
 (2 rows)
 
 select r, r is null as isnull, r is not null as isnotnull