diff --git a/gcc/c-family/c-ada-spec.cc b/gcc/c-family/c-ada-spec.cc
--- a/gcc/c-family/c-ada-spec.cc
+++ b/gcc/c-family/c-ada-spec.cc
@@ -2783,6 +2783,103 @@ dump_ada_methods (pretty_printer *buffer, tree node, int spc)
   return 1;
 }
 
+/* Return true if NODE needs an explicit Ada layout to describe C++ tail
+   padding, either because its object size exceeds its size as a base class or
+   because it places a field in a direct base class's tail padding.  */
+
+static bool
+needs_tail_padding_layout (tree node)
+{
+  if (!cpp_check || !RECORD_OR_UNION_TYPE_P (node))
+    return false;
+
+  const int data_size = cpp_check (node, GET_AS_BASE_SIZE);
+  const HOST_WIDE_INT object_size = int_size_in_bytes (node);
+  return (data_size >= 0 && object_size > data_size)
+	 || cpp_check (node, REUSES_BASE_TAIL_PADDING);
+}
+
+/* Return true if all of NODE's fields that are visible in the generated Ada
+   record have constant positions and sizes suitable for component clauses.  */
+
+static bool
+has_constant_field_layout (tree node)
+{
+  for (tree field = TYPE_FIELDS (node); field; field = TREE_CHAIN (field))
+    if (TREE_CODE (field) == FIELD_DECL
+	&& DECL_NAME (field)
+	&& !DECL_VIRTUAL_P (field)
+	&& (!DECL_FIELD_OFFSET (field)
+	    || !DECL_FIELD_BIT_OFFSET (field)
+	    || !DECL_SIZE (field)
+	    || !tree_fits_uhwi_p (DECL_FIELD_OFFSET (field))
+	    || !tree_fits_uhwi_p (DECL_FIELD_BIT_OFFSET (field))
+	    || !tree_fits_uhwi_p (DECL_SIZE (field))
+	    || tree_to_uhwi (DECL_SIZE (field)) == 0))
+      return false;
+
+  return true;
+}
+
+/* Dump the size and component clauses needed to preserve NODE's C++ tail
+   padding layout.  TYPE is the declaration used for Ada name qualification.  */
+
+static void
+dump_ada_tail_padding_layout (pretty_printer *buffer, tree node, tree type,
+                              int spc)
+{
+  const int data_size = cpp_check (node, GET_AS_BASE_SIZE);
+  const HOST_WIDE_INT object_size = int_size_in_bytes (node);
+
+  gcc_assert (data_size >= 0 && object_size >= 0);
+
+  newline_and_indent (buffer, spc);
+  pp_string (buffer, "for ");
+  dump_ada_node (buffer, TYPE_NAME (node), type, spc, false, true);
+  pp_string (buffer, "'Size use ");
+  pp_wide_integer (buffer, (HOST_WIDE_INT) data_size * BITS_PER_UNIT);
+  pp_semicolon (buffer);
+
+  newline_and_indent (buffer, spc);
+  pp_string (buffer, "for ");
+  dump_ada_node (buffer, TYPE_NAME (node), type, spc, false, true);
+  pp_string (buffer, "'Object_Size use ");
+  pp_wide_integer (buffer, object_size * BITS_PER_UNIT);
+  pp_semicolon (buffer);
+
+  newline_and_indent (buffer, spc);
+  pp_string (buffer, "for ");
+  dump_ada_node (buffer, TYPE_NAME (node), type, spc, false, true);
+  pp_string (buffer, " use record");
+
+  for (tree field = TYPE_FIELDS (node); field; field = TREE_CHAIN (field))
+    if (TREE_CODE (field) == FIELD_DECL
+	&& DECL_NAME (field)
+	&& !DECL_VIRTUAL_P (field))
+      {
+	const unsigned HOST_WIDE_INT bitpos
+	  = tree_to_uhwi (DECL_FIELD_OFFSET (field)) * BITS_PER_UNIT
+	    + tree_to_uhwi (DECL_FIELD_BIT_OFFSET (field));
+	const unsigned HOST_WIDE_INT position = bitpos / BITS_PER_UNIT;
+	const unsigned HOST_WIDE_INT first_bit = bitpos % BITS_PER_UNIT;
+	const unsigned HOST_WIDE_INT last_bit
+	  = first_bit + tree_to_uhwi (DECL_SIZE (field)) - 1;
+
+	newline_and_indent (buffer, spc + INDENT_INCR);
+	dump_ada_decl_name (buffer, field, false);
+	pp_string (buffer, " at ");
+	pp_unsigned_wide_integer (buffer, position);
+	pp_string (buffer, " range ");
+	pp_unsigned_wide_integer (buffer, first_bit);
+	pp_string (buffer, " .. ");
+	pp_unsigned_wide_integer (buffer, last_bit);
+	pp_semicolon (buffer);
+      }
+
+  newline_and_indent (buffer, spc);
+  pp_string (buffer, "end record;");
+}
+
 /* Dump in BUFFER a forward declaration for TYPE present inside T.
    SPC is the indentation level.  */
 
@@ -3816,6 +3913,18 @@ dump_ada_structure (pretty_printer *buffer, tree node, tree type, bool nested,
 
   need_semicolon = !dump_ada_methods (buffer, node, spc);
 
+  if (needs_tail_padding_layout (node) && has_constant_field_layout (node))
+    {
+      if (need_semicolon)
+	{
+	  need_semicolon = false;
+	  pp_semicolon (buffer);
+	}
+
+      pp_newline (buffer);
+      dump_ada_tail_padding_layout (buffer, node, type, spc);
+    }
+
   /* Print the static fields of the structure, if any.  */
   for (tree tmp = TYPE_FIELDS (node); tmp; tmp = TREE_CHAIN (tmp))
     {
diff --git a/gcc/c-family/c-ada-spec.h b/gcc/c-family/c-ada-spec.h
--- a/gcc/c-family/c-ada-spec.h
+++ b/gcc/c-family/c-ada-spec.h
@@ -25,6 +25,7 @@ along with GCC; see the file COPYING3.  If not see
 /* In c-ada-spec.cc  */
 
 enum cpp_operation {
+  GET_AS_BASE_SIZE,
   GET_FUNCTION_QUALIFIERS,
   HAS_DEPENDENT_TEMPLATE_ARGS,
   IS_ABSTRACT,
@@ -34,7 +35,8 @@ enum cpp_operation {
   IS_COPY_CONSTRUCTOR,
   IS_MOVE_CONSTRUCTOR,
   IS_TEMPLATE,
-  IS_TRIVIAL
+  IS_TRIVIAL,
+  REUSES_BASE_TAIL_PADDING
 };
 
 enum cpp_function_qualifier {
diff --git a/gcc/cp/decl2.cc b/gcc/cp/decl2.cc
--- a/gcc/cp/decl2.cc
+++ b/gcc/cp/decl2.cc
@@ -5257,6 +5257,15 @@ cpp_check (tree t, cpp_operation op)
 {
   switch (op)
     {
+      case GET_AS_BASE_SIZE:
+	{
+	  if (!CLASS_TYPE_P (t) || !COMPLETE_TYPE_P (t))
+	    return -1;
+
+	  const HOST_WIDE_INT size
+	    = int_size_in_bytes (CLASSTYPE_AS_BASE (t));
+	  return size >= 0 && size <= INT_MAX ? size : -1;
+	}
       case GET_FUNCTION_QUALIFIERS:
 	{
 	  int qualifiers = 0;
@@ -5305,6 +5314,47 @@ cpp_check (tree t, cpp_operation op)
 	return TREE_CODE (t) == TEMPLATE_DECL;
       case IS_TRIVIAL:
 	return trivial_type_p (t);
+      case REUSES_BASE_TAIL_PADDING:
+	{
+	  if (!CLASS_TYPE_P (t) || !COMPLETE_TYPE_P (t) || !TYPE_BINFO (t))
+	    return 0;
+
+	  for (unsigned int i = 0;
+	       i < BINFO_N_BASE_BINFOS (TYPE_BINFO (t));
+	       ++i)
+	    {
+	      tree base_binfo = BINFO_BASE_BINFO (TYPE_BINFO (t), i);
+	      if (BINFO_VIRTUAL_P (base_binfo)
+		  || !tree_fits_uhwi_p (BINFO_OFFSET (base_binfo)))
+		continue;
+
+	      tree base_type = BINFO_TYPE (base_binfo);
+	      const HOST_WIDE_INT data_size
+		= int_size_in_bytes (CLASSTYPE_AS_BASE (base_type));
+	      const HOST_WIDE_INT object_size = int_size_in_bytes (base_type);
+	      if (data_size < 0 || object_size <= data_size)
+		continue;
+
+	      const unsigned HOST_WIDE_INT base_offset
+		= tree_to_uhwi (BINFO_OFFSET (base_binfo));
+	      for (tree field = TYPE_FIELDS (t); field;
+		   field = DECL_CHAIN (field))
+		if (TREE_CODE (field) == FIELD_DECL
+		    && !DECL_ARTIFICIAL (field)
+		    && tree_fits_uhwi_p (bit_position (field)))
+		  {
+		    const unsigned HOST_WIDE_INT field_bitpos
+		      = tree_to_uhwi (bit_position (field));
+		    if (field_bitpos
+			>= (base_offset + data_size) * BITS_PER_UNIT
+			&& field_bitpos < ((base_offset + object_size)
+					   * BITS_PER_UNIT))
+		      return 1;
+		  }
+	    }
+
+	  return 0;
+	}
       default:
         return 0;
     }
diff --git a/gcc/testsuite/g++.dg/ada-spec/inherited-tail-padding.C b/gcc/testsuite/g++.dg/ada-spec/inherited-tail-padding.C
new file mode 100644
--- /dev/null
+++ b/gcc/testsuite/g++.dg/ada-spec/inherited-tail-padding.C
@@ -0,0 +1,114 @@
+/* { dg-do compile } */
+/* { dg-require-effective-target lp64 } */
+/* { dg-options "-fdump-ada-spec-slim" } */
+/* { dg-final { scan-file inherited_tail_padding_c.ads "for Tail_Base'Size use 96;" } } */
+/* { dg-final { scan-file inherited_tail_padding_c.ads "for Tail_Base'Object_Size use 128;" } } */
+/* { dg-final { scan-file inherited_tail_padding_c.ads "value_u at 8 range 0 .. 31;" } } */
+/* { dg-final { scan-file inherited_tail_padding_c.ads "extra_u at 12 range 0 .. 31;" } } */
+/* { dg-final { scan-file inherited_tail_padding_c.ads "for Plain_Base'Size use 24;" } } */
+/* { dg-final { scan-file inherited_tail_padding_c.ads "derived_char at 3 range 0 .. 7;" } } */
+/* { dg-final { scan-file inherited_tail_padding_c.ads "extra at 7 range 0 .. 7;" } } */
+
+class Tail_Base
+{
+public:
+  Tail_Base (int value);
+  virtual ~Tail_Base ();
+  int value () const { return value_; }
+
+protected:
+  int value_;
+};
+
+class Tail_Derived : public Tail_Base
+{
+public:
+  Tail_Derived (int value, int extra);
+  ~Tail_Derived () override;
+  int extra () const { return extra_; }
+
+private:
+  int extra_;
+};
+
+Tail_Base::Tail_Base (int value) : value_ (value) {}
+Tail_Base::~Tail_Base () = default;
+Tail_Derived::Tail_Derived (int value, int extra)
+  : Tail_Base (value), extra_ (extra) {}
+Tail_Derived::~Tail_Derived () = default;
+
+extern "C" unsigned long
+cpp_base_size ()
+{
+  return sizeof (Tail_Base);
+}
+
+extern "C" unsigned long
+cpp_derived_size ()
+{
+  return sizeof (Tail_Derived);
+}
+
+extern "C" int
+cpp_value (const Tail_Derived *object)
+{
+  return object->value ();
+}
+
+extern "C" int
+cpp_extra (const Tail_Derived *object)
+{
+  return object->extra ();
+}
+
+struct Plain_Base
+{
+  short base_short;
+  char base_char;
+  Plain_Base () : base_short (1), base_char (2) {}
+};
+
+struct Plain_Derived : Plain_Base
+{
+  char derived_char;
+  Plain_Derived () : derived_char (3) {}
+};
+
+struct Plain_Left
+{
+  short left_short;
+  char left_char;
+  Plain_Left () : left_short (4), left_char (5) {}
+};
+
+struct Plain_Right
+{
+  short right_short;
+  char right_char;
+  Plain_Right () : right_short (6), right_char (7) {}
+};
+
+struct Plain_Both : Plain_Left, Plain_Right
+{
+  char extra;
+  Plain_Both () : extra (8) {}
+};
+
+extern "C" Plain_Derived *cpp_plain_create () { return new Plain_Derived; }
+extern "C" void cpp_plain_delete (Plain_Derived *p) { delete p; }
+extern "C" unsigned long cpp_plain_size () { return sizeof (Plain_Derived); }
+extern "C" int cpp_plain_values (const Plain_Derived *p)
+{
+  return p->base_short + p->base_char + p->derived_char;
+}
+
+extern "C" Plain_Both *cpp_both_create () { return new Plain_Both; }
+extern "C" void cpp_both_delete (Plain_Both *p) { delete p; }
+extern "C" unsigned long cpp_both_plain_size () { return sizeof (Plain_Both); }
+extern "C" int cpp_both_values (const Plain_Both *p)
+{
+  return p->left_short + p->left_char + p->right_short
+    + p->right_char + p->extra;
+}
+
+/* { dg-final { cleanup-ada-spec } } */