diff --git a/gcc/c-family/c-common.cc b/gcc/c-family/c-common.cc
index e7e371fd26f..15b90bae8b5 100644
--- a/gcc/c-family/c-common.cc
+++ b/gcc/c-family/c-common.cc
@@ -430,6 +430,7 @@ const struct c_common_resword c_common_reswords[] =
   { "__builtin_choose_expr", RID_CHOOSE_EXPR, D_CONLY },
   { "__builtin_complex", RID_BUILTIN_COMPLEX, D_CONLY },
   { "__builtin_convertvector", RID_BUILTIN_CONVERTVECTOR, 0 },
+  { "__builtin_counted_by_ref", RID_BUILTIN_COUNTED_BY_REF, D_CONLY },
   { "__builtin_has_attribute", RID_BUILTIN_HAS_ATTRIBUTE, 0 },
   { "__builtin_launder", RID_BUILTIN_LAUNDER, D_CXXONLY },
   { "__builtin_shuffle", RID_BUILTIN_SHUFFLE, 0 },
diff --git a/gcc/c-family/c-common.h b/gcc/c-family/c-common.h
index 027f077d51b..4400d2c5d43 100644
--- a/gcc/c-family/c-common.h
+++ b/gcc/c-family/c-common.h
@@ -110,6 +110,7 @@ enum rid
   RID_TYPES_COMPATIBLE_P,      RID_BUILTIN_COMPLEX,	   RID_BUILTIN_SHUFFLE,
   RID_BUILTIN_SHUFFLEVECTOR,   RID_BUILTIN_CONVERTVECTOR,  RID_BUILTIN_TGMATH,
   RID_BUILTIN_HAS_ATTRIBUTE,   RID_BUILTIN_ASSOC_BARRIER,  RID_BUILTIN_STDC,
+  RID_BUILTIN_COUNTED_BY_REF,
   RID_DFLOAT32, RID_DFLOAT64, RID_DFLOAT128,
 
   /* TS 18661-3 keywords, in the same sequence as the TI_* values.  */
diff --git a/gcc/c/c-decl.cc b/gcc/c/c-decl.cc
index aa7f69d1b7b..1145dde9bb1 100644
--- a/gcc/c/c-decl.cc
+++ b/gcc/c/c-decl.cc
@@ -11788,6 +11788,7 @@ names_builtin_p (const char *name)
     case RID_BUILTIN_SHUFFLE:
     case RID_BUILTIN_SHUFFLEVECTOR:
     case RID_BUILTIN_STDC:
+    case RID_BUILTIN_COUNTED_BY_REF:
     case RID_CHOOSE_EXPR:
     case RID_OFFSETOF:
     case RID_TYPES_COMPATIBLE_P:
diff --git a/gcc/c/c-parser.cc b/gcc/c/c-parser.cc
index aff5af17430..0feddf72f95 100644
--- a/gcc/c/c-parser.cc
+++ b/gcc/c/c-parser.cc
@@ -10647,6 +10647,35 @@ c_parser_predefined_identifier (c_parser *parser)
   return expr;
 }
 
+/* Check whether the ARRAY_REF has an counted-by object associated with it
+   through the "counted_by" attribute.  */
+static bool
+has_counted_by_object (tree array_ref)
+{
+  /* Currently, only when the array_ref is an indirect_ref to a call to the
+     .ACCESS_WITH_SIZE, return true.
+     More cases can be included later when the counted_by attribute is
+     extended to other situations.  */
+  if ((TREE_CODE (array_ref) == INDIRECT_REF)
+      && is_access_with_size_p (TREE_OPERAND (array_ref, 0)))
+    return true;
+  return false;
+}
+
+/* Get the reference to the counted-by object associated with the ARRAY_REF.  */
+static tree
+get_counted_by_ref (tree array_ref)
+{
+  /* Currently, only when the array_ref is an indirect_ref to a call to the
+     .ACCESS_WITH_SIZE, get the corresponding counted_by ref.
+     More cases can be included later when the counted_by attribute is
+     extended to other situations.  */
+  if ((TREE_CODE (array_ref) == INDIRECT_REF)
+      && is_access_with_size_p (TREE_OPERAND (array_ref, 0)))
+    return CALL_EXPR_ARG (TREE_OPERAND (array_ref, 0), 1);
+  return NULL_TREE;
+}
+
 /* Parse a postfix expression (C90 6.3.1-6.3.2, C99 6.5.1-6.5.2,
    C11 6.5.1-6.5.2).  Compound literals aren't handled here; callers have to
    call c_parser_postfix_expression_after_paren_type on encountering them.
@@ -11741,6 +11770,54 @@ c_parser_postfix_expression (c_parser *parser)
 	    set_c_expr_source_range (&expr, loc, close_paren_loc);
 	    break;
 	  }
+	case RID_BUILTIN_COUNTED_BY_REF:
+	  {
+	    vec<c_expr_t, va_gc> *cexpr_list;
+	    c_expr_t *e_p;
+	    location_t close_paren_loc;
+
+	    in_builtin_counted_by_ref = true;
+
+	    c_parser_consume_token (parser);
+	    if (!c_parser_get_builtin_args (parser,
+					    "__builtin_counted_by_ref",
+					    &cexpr_list, false,
+					    &close_paren_loc))
+	      {
+		expr.set_error ();
+		goto error_exit;
+	      }
+	    if (vec_safe_length (cexpr_list) != 1)
+	      {
+		error_at (loc, "wrong number of arguments to "
+			       "%<__builtin_counted_by_ref%>");
+		expr.set_error ();
+		goto error_exit;
+	      }
+
+	    e_p = &(*cexpr_list)[0];
+
+	    if (TREE_CODE (TREE_TYPE (e_p->value)) != ARRAY_TYPE)
+	      {
+		error_at (loc, "the argument must be an array"
+			       "%<__builtin_counted_by_ref%>");
+		expr.set_error ();
+		goto error_exit;
+	      }
+
+	    if (has_counted_by_object ((*cexpr_list)[0].value))
+	      expr.value
+		= get_counted_by_ref ((*cexpr_list)[0].value);
+	    else
+	      expr.value
+		= build_int_cst (build_pointer_type (void_type_node), 0);
+
+	    set_c_expr_source_range (&expr, loc, close_paren_loc);
+
+error_exit:
+	    in_builtin_counted_by_ref = false;
+	    break;
+	  }
 	case RID_BUILTIN_SHUFFLE:
 	  {
 	    vec<c_expr_t, va_gc> *cexpr_list;
diff --git a/gcc/c/c-tree.h b/gcc/c/c-tree.h
index 57befb94c08..1e8a090d3b6 100644
--- a/gcc/c/c-tree.h
+++ b/gcc/c/c-tree.h
@@ -737,6 +737,7 @@ extern int c_type_dwarf_attribute (const_tree, int);
 extern int in_alignof;
 extern int in_sizeof;
 extern int in_typeof;
+extern bool in_builtin_counted_by_ref;
 extern bool c_in_omp_for;
 extern bool c_omp_array_section_p;
 
diff --git a/gcc/c/c-typeck.cc b/gcc/c/c-typeck.cc
index 58b2724b39e..ed9444e2077 100644
--- a/gcc/c/c-typeck.cc
+++ b/gcc/c/c-typeck.cc
@@ -74,6 +74,9 @@ int in_sizeof;
 /* The level of nesting inside "typeof".  */
 int in_typeof;
 
+/* inside "builtin_counted_by_ref".  */
+bool in_builtin_counted_by_ref;
+
 /* True when parsing OpenMP loop expressions.  */
 bool c_in_omp_for;
 
@@ -2848,7 +2851,9 @@ build_component_ref (location_t loc, tree datum, tree component,
 	  bool use_datum_quals;
 	  tree counted_by_type = NULL_TREE;
 	  /* Do not handle counted_by when in typeof and alignof operator.  */
-	  handle_counted_by = handle_counted_by && !in_typeof && !in_alignof;
+	  handle_counted_by = handle_counted_by
+			      && !(in_typeof && !in_builtin_counted_by_ref)
+			      && !in_alignof;
 	  tree counted_by_ref = handle_counted_by
 				? build_counted_by_ref (datum, subdatum,
 							&counted_by_type)
diff --git a/gcc/doc/extend.texi b/gcc/doc/extend.texi
index 2d795ba7e59..268e50677d7 100644
--- a/gcc/doc/extend.texi
+++ b/gcc/doc/extend.texi
@@ -15287,6 +15287,61 @@ initializers of variables usable in constant expressions.   For more details
 refer to the latest revision of the C++ standard.
 @enddefbuiltin
 
+@defbuiltin{@var{type} __builtin_counted_by_ref (@var{ptr})}
+The built-in function @code{__builtin_counted_by_ref} checks whether the array
+object pointed by the pointer @var{ptr} has another object associated with it
+that represents the number of elements in the array object through the
+@code{counted_by} attribute (i.e. the counted-by object). If so, returns a
+pointer to the corresponding counted-by object.
+If such counted-by object does not exist, returns a NULL pointer.
+
+This built-in function is only available in C for now.
+
+The argument @var{ptr} must be a pointer to an array.
+The @var{type} of the returned value must be a pointer type pointing to the
+corresponding type of the counted-by object or a VOID pointer type in case
+of a NULL pointer being returned.
+
+For example:
+
+@smallexample
+struct foo1 @{
+  int counter;
+  struct bar1 array[] __attribute__((counted_by (counter)));
+@} *p;
+
+struct foo2 @{
+  int other;
+  struct bar2 array[];
+@} *q;
+@end smallexample
+
+@noindent
+the following call to the built-in
+
+@smallexample
+__builtin_counted_by_ref (p->array)
+@end smallexample
+
+@noindent
+returns:
+
+@smallexample
+&p->counter with type @code{int *}.
+@end smallexample
+
+@noindent
+However, the following call to the built-in
+
+@smallexample
+__builtin_counted_by_ref (q->array)
+@end smallexample
+
+@noindent
+returns a void NULL pointer.
+
+@enddefbuiltin
+
 @defbuiltin{void __builtin_clear_padding (@var{ptr})}
 The built-in function @code{__builtin_clear_padding} function clears
 padding bits inside of the object representation of object pointed by
diff --git a/gcc/testsuite/gcc.dg/builtin-counted-by-ref-1.c b/gcc/testsuite/gcc.dg/builtin-counted-by-ref-1.c
new file mode 100644
index 00000000000..0939708510a
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/builtin-counted-by-ref-1.c
@@ -0,0 +1,97 @@
+/* Test the code generation for the new __builtin_counted_by_ref.  */
+/* { dg-do run } */
+/* { dg-options "-O2" } */
+#include <stdio.h>
+
+struct annotated {
+  char b;
+  int c[] __attribute ((counted_by (b)));
+} *array_annotated; 
+
+struct flex {
+  short b;
+  int c[];
+} *array_flex;
+
+struct nested_annotated {
+  struct {
+    union {
+      int b;
+      float f;
+    };
+    int n;
+  };
+  char c[] __attribute__ ((counted_by (b)));
+} *array_nested_annotated;
+
+struct nested_flex {
+  struct {
+    union {
+      unsigned int b;
+      float f;
+    };
+    int n;
+  };
+  char c[];
+} *array_nested_flex;
+
+#define MY_ALLOC(P, FAM, COUNT) ({ \
+  typeof(P) __p; \
+  size_t __size = sizeof(*P) + sizeof(*P->FAM) * COUNT; \
+  __p = (typeof(P)) __builtin_malloc(__size); \
+  __builtin_memset(__p, 0, __size); \
+  typeof(_Generic(__builtin_counted_by_ref(__p->FAM), \
+	 void *: (size_t *)NULL, \
+	 default: __builtin_counted_by_ref(__p->FAM))) \
+    ret = __builtin_counted_by_ref(__p->FAM); \
+  if (ret) \
+    *ret = COUNT; \
+  if (sizeof (__builtin_counted_by_ref (__p->FAM)) != sizeof (char *)) \
+    __builtin_abort (); \
+  P = __p; \
+})
+
+int count;
+
+int main(int argc, char *argv[])
+{
+  MY_ALLOC(array_annotated, c, 10);
+  if (array_annotated->b != 10)
+    __builtin_abort ();
+
+  MY_ALLOC(array_flex, c, 20);
+  if (array_flex->b == 20)
+    __builtin_abort ();
+
+  MY_ALLOC(array_nested_annotated, c, 30);
+  if (array_nested_annotated->b != 30)
+    __builtin_abort ();
+
+  MY_ALLOC(array_nested_flex, c, 40);
+  if (array_nested_flex->b == 40)
+    __builtin_abort ();
+
+  count = array_annotated->b * 2 + array_nested_annotated->b * 3;
+  struct annotated * annotated_p;
+  struct flex * flex_p;
+  struct nested_annotated * nested_annotated_p;
+  struct nested_flex * nested_flex_p;  
+
+  MY_ALLOC(annotated_p, c, count);
+  if (annotated_p->b != count)
+    __builtin_abort ();
+
+  MY_ALLOC(flex_p, c, count * 2);
+  if (flex_p->b == count * 2)
+    __builtin_abort ();
+
+  MY_ALLOC(nested_annotated_p, c, count * 3);
+  if (nested_annotated_p->b != count * 3)
+    __builtin_abort ();
+
+  MY_ALLOC(nested_flex_p, c, count * 4);
+  if (nested_flex_p->b == count * 4)
+    __builtin_abort ();
+
+  return 0;
+}
diff --git a/gcc/testsuite/gcc.dg/builtin-counted-by-ref.c b/gcc/testsuite/gcc.dg/builtin-counted-by-ref.c
new file mode 100644
index 00000000000..78650a5d20e
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/builtin-counted-by-ref.c
@@ -0,0 +1,58 @@
+/* Testing the correct usage of the new __builtin_counted_by_ref.  */
+/* { dg-do compile } */
+/* { dg-options "-O" } */
+
+#include <stdio.h>
+
+struct annotated {
+  size_t b;
+  int other;
+  int c[] __attribute ((counted_by (b)));
+} *array_annotated;
+
+struct flex {
+  size_t b;
+  int other;
+  int c[];
+} *array_flex;
+
+#define MY_ALLOC(P, FAM, COUNT) ({ \
+  typeof(P) __p; \
+  size_t __size = sizeof(*P) + sizeof(*P->FAM) * COUNT; \
+  __p = (typeof(P)) __builtin_malloc(__size); \
+  typeof(_Generic(__builtin_counted_by_ref(__p->FAM), \
+	 void *: (size_t *)NULL, \
+	 default: __builtin_counted_by_ref(__p->FAM))) \
+    ret = __builtin_counted_by_ref(__p->FAM); \
+  if (ret) \
+    *ret = COUNT; \
+  P = __p; \
+})
+
+extern char c_count;
+extern short s_count;
+extern int i_count;
+extern long l_count;
+extern float f_count;
+
+extern int * foo ();
+
+int main(int argc, char *argv[])
+{
+  /* The good usages.  */
+  MY_ALLOC(array_annotated, c, 10);
+  MY_ALLOC(array_flex, c, 20);
+  MY_ALLOC(array_annotated, c, c_count);
+  MY_ALLOC(array_flex, c, i_count);
+  MY_ALLOC(array_annotated, c, l_count);
+  MY_ALLOC(array_flex, c, c_count * 3);
+  MY_ALLOC(array_annotated, c, l_count * i_count);
+
+  /* The bad usages, issue errors.  */
+  __builtin_counted_by_ref (); /* { dg-error "wrong number of arguments to" } */
+  __builtin_counted_by_ref (array_annotated->c, 10); /* { dg-error "wrong number of arguments to" } */
+  __builtin_counted_by_ref (array_annotated->other); /* { dg-error "the argument must be an array" } */
+  __builtin_counted_by_ref (foo());  /* { dg-error "the argument must be an array" } */
+
+  return 0;
+}
