diff --git a/bits/floatn-common.h b/bits/floatn-common.h
new file mode 100644
index 0000000..1b3ab51
--- /dev/null
+++ b/bits/floatn-common.h
@@ -0,0 +1,292 @@
+/* Macros to control TS 18661-3 glibc features where the same
+   definitions are appropriate for all platforms.
+   Copyright (C) 2017 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+
+   The GNU C Library is free software; you can redistribute it and/or
+   modify it under the terms of the GNU Lesser General Public
+   License as published by the Free Software Foundation; either
+   version 2.1 of the License, or (at your option) any later version.
+
+   The GNU C Library is distributed in the hope that it will be useful,
+   but WITHOUT ANY WARRANTY; without even the implied warranty of
+   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+   Lesser General Public License for more details.
+
+   You should have received a copy of the GNU Lesser General Public
+   License along with the GNU C Library; if not, see
+   <http://www.gnu.org/licenses/>.  */
+
+#ifndef _BITS_FLOATN_COMMON_H
+#define _BITS_FLOATN_COMMON_H
+
+#include <features.h>
+
+/* This header should be included at the bottom of each bits/floatn.h.
+   It defines the following macros for each _FloatN and _FloatNx type,
+   where the same definitions, or definitions based only on the macros
+   in bits/floatn.h, are appropriate for all glibc configurations.  */
+
+/* Defined to 1 if the current compiler invocation provides a
+   floating-point type with the right format for this type, and this
+   glibc includes corresponding *fN or *fNx interfaces for it.  */
+#define __HAVE_FLOAT16 0
+#define __HAVE_FLOAT32 0
+#define __HAVE_FLOAT64 0
+#define __HAVE_FLOAT32X 0
+#define __HAVE_FLOAT64X 0
+#define __HAVE_FLOAT128X 0
+
+/* Defined to 1 if the corresponding __HAVE_<type> macro is 1 and the
+   type is the first with its format in the sequence of (the default
+   choices for) float, double, long double, _Float16, _Float32,
+   _Float64, _Float128, _Float32x, _Float64x, _Float128x for this
+   glibc; that is, if functions present once per floating-point format
+   rather than once per type are present for this type.
+
+   All configurations supported by glibc have _Float32 the same format
+   as float, _Float64 and _Float32x the same format as double, the
+   _Float64x the same format as either long double or _Float128.  No
+   configurations support _Float128x or, as of GCC 7, have compiler
+   support for a type meeting the requirements for _Float128x.  */
+#define __HAVE_DISTINCT_FLOAT16 __HAVE_FLOAT16
+#define __HAVE_DISTINCT_FLOAT32 0
+#define __HAVE_DISTINCT_FLOAT64 0
+#define __HAVE_DISTINCT_FLOAT32X 0
+#define __HAVE_DISTINCT_FLOAT64X 0
+#define __HAVE_DISTINCT_FLOAT128X __HAVE_FLOAT128X
+
+/* Defined to 1 if __HAVE_FLOAT64X is 1 and _Float64x has the format
+   of long double.  Otherwise, if __HAVE_FLOAT64X is 1, _Float64x has
+   the format of _Float128, which must be different from that of long
+   double.  */
+#define __HAVE_FLOAT64X_LONG_DOUBLE 0
+
+/* Defined to 1 if any _FloatN or _FloatNx types that are not
+   ABI-distinct are however distinct types at the C language level (so
+   for the purposes of __builtin_types_compatible_p and _Generic).  */
+#if __GNUC_PREREQ (7, 0) && !defined __cplusplus
+# define __HAVE_FLOATN_NOT_TYPEDEF 1
+#else
+# define __HAVE_FLOATN_NOT_TYPEDEF 0
+#endif
+
+/* Defined to concatenate the literal suffix to be used with _FloatN
+   or _FloatNx types, if __HAVE_<type> is 1.  The corresponding
+   literal suffixes exist since GCC 7, for C only.  */
+#if __HAVE_FLOAT16
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+/* No corresponding suffix available for this type.  */
+#  define __f16(x) ((_Float16) x##f)
+# else
+#  define __f16(x) x##f16
+# endif
+#endif
+
+#if __HAVE_FLOAT32
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  define __f32(x) x##f
+# else
+#  define __f32(x) x##f32
+# endif
+#endif
+
+#if __HAVE_FLOAT64
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  define __f64(x) x
+# else
+#  define __f64(x) x##f64
+# endif
+#endif
+
+#if __HAVE_FLOAT32X
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  define __f32x(x) x
+# else
+#  define __f32x(x) x##f32x
+# endif
+#endif
+
+#if __HAVE_FLOAT64X
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  if __HAVE_FLOAT64X_LONG_DOUBLE
+#   define __f64x(x) x##l
+#  else
+#   define __f64x(x) __f128 (x)
+#  endif
+# else
+#  define __f64x(x) x##f64x
+# endif
+#endif
+
+#if __HAVE_FLOAT128X
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  error "_Float128X supported but no constant suffix"
+# else
+#  define __f128x(x) x##f128x
+# endif
+#endif
+
+/* Defined to a complex type if __HAVE_<type> is 1.  */
+#if __HAVE_FLOAT16
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+typedef _Complex float __cfloat16 __attribute__ ((__mode__ (__HC__)));
+#  define __CFLOAT16 __cfloat16
+# else
+#  define __CFLOAT16 _Complex _Float16
+# endif
+#endif
+
+#if __HAVE_FLOAT32
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  define __CFLOAT32 _Complex float
+# else
+#  define __CFLOAT32 _Complex _Float32
+# endif
+#endif
+
+#if __HAVE_FLOAT64
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  define __CFLOAT64 _Complex double
+# else
+#  define __CFLOAT64 _Complex _Float64
+# endif
+#endif
+
+#if __HAVE_FLOAT32X
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  define __CFLOAT32X _Complex double
+# else
+#  define __CFLOAT32X _Complex _Float32x
+# endif
+#endif
+
+#if __HAVE_FLOAT64X
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  if __HAVE_FLOAT64X_LONG_DOUBLE
+#   define __CFLOAT64X _Complex long double
+#  else
+#   define __CFLOAT64X __CFLOAT128
+#  endif
+# else
+#  define __CFLOAT64X _Complex _Float64x
+# endif
+#endif
+
+#if __HAVE_FLOAT128X
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  error "_Float128X supported but no complex type"
+# else
+#  define __CFLOAT128X _Complex _Float128x
+# endif
+#endif
+
+/* The remaining of this file provides support for older compilers.  */
+#if __HAVE_FLOAT16
+
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+typedef float _Float16 __attribute__ ((__mode__ (__HF__)));
+# endif
+
+# if !__GNUC_PREREQ (7, 0)
+#  define __builtin_huge_valf16() ((_Float16) __builtin_huge_val ())
+#  define __builtin_inff16() ((_Float16) __builtin_inf ())
+#  define __builtin_nanf16(x) ((_Float16) __builtin_nan (x))
+#  define __builtin_nansf16(x) ((_Float16) __builtin_nans (x))
+# endif
+
+#endif
+
+#if __HAVE_FLOAT32
+
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+typedef float _Float32;
+# endif
+
+# if !__GNUC_PREREQ (7, 0)
+#  define __builtin_huge_valf32() (__builtin_huge_valf ())
+#  define __builtin_inff32() (__builtin_inff ())
+#  define __builtin_nanf32(x) (__builtin_nanf (x))
+#  define __builtin_nansf32(x) (__builtin_nansf (x))
+# endif
+
+#endif
+
+#if __HAVE_FLOAT64
+
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+typedef double _Float64;
+# endif
+
+# if !__GNUC_PREREQ (7, 0)
+#  define __builtin_huge_valf64() (__builtin_huge_val ())
+#  define __builtin_inff64() (__builtin_inf ())
+#  define __builtin_nanf64(x) (__builtin_nan (x))
+#  define __builtin_nansf64(x) (__builtin_nans (x))
+# endif
+
+#endif
+
+#if __HAVE_FLOAT32X
+
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+typedef double _Float32x;
+# endif
+
+# if !__GNUC_PREREQ (7, 0)
+#  define __builtin_huge_valf32x() (__builtin_huge_val ())
+#  define __builtin_inff32x() (__builtin_inf ())
+#  define __builtin_nanf32x(x) (__builtin_nan (x))
+#  define __builtin_nansf32x(x) (__builtin_nans (x))
+# endif
+
+#endif
+
+#if __HAVE_FLOAT64X
+
+# if __HAVE_FLOAT64X_LONG_DOUBLE
+
+#  if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+typedef long double _Float64x;
+#  endif
+
+#  if !__GNUC_PREREQ (7, 0)
+#   define __builtin_huge_valf64x() (__builtin_huge_vall ())
+#   define __builtin_inff64x() (__builtin_infl ())
+#   define __builtin_nanf64x(x) (__builtin_nanl (x))
+#   define __builtin_nansf64x(x) (__builtin_nansl (x))
+#  endif
+
+# else
+
+#  if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+typedef _Float128 _Float64x;
+#  endif
+
+#  if !__GNUC_PREREQ (7, 0)
+#   define __builtin_huge_valf64x() (__builtin_huge_valf128 ())
+#   define __builtin_inff64x() (__builtin_inff128 ())
+#   define __builtin_nanf64x(x) (__builtin_nanf128 (x))
+#   define __builtin_nansf64x(x) (__builtin_nansf128 (x))
+#  endif
+
+# endif
+
+#endif
+
+#if __HAVE_FLOAT128X
+
+# if !__GNUC_PREREQ (7, 0) || defined __cplusplus
+#  error "_Float128x supported but no type"
+# endif
+
+# if !__GNUC_PREREQ (7, 0)
+#  define __builtin_huge_valf128x() ((_Float128x) __builtin_huge_val ())
+#  define __builtin_inff128x() ((_Float128x) __builtin_inf ())
+#  define __builtin_nanf128x(x) ((_Float128x) __builtin_nan (x))
+#  define __builtin_nansf128x(x) ((_Float128x) __builtin_nans (x))
+# endif
+
+#endif
+
+#endif /* _BITS_FLOATN_COMMON_H */
diff --git a/bits/floatn.h b/bits/floatn.h
index a806496..78eb0f4 100644
--- a/bits/floatn.h
+++ b/bits/floatn.h
@@ -33,3 +33,5 @@
 /* Defined to a complex binary128 type if __HAVE_FLOAT128 is 1.
    E.g.: #define __CFLOAT128 _Complex _Float128.  */
 #undef __CFLOAT128
+
+#include <bits/floatn-common.h>
diff --git a/math/Makefile b/math/Makefile
index 2d47209..1feb425 100644
--- a/math/Makefile
+++ b/math/Makefile
@@ -29,7 +29,7 @@ headers		:= math.h bits/mathcalls.h bits/mathinline.h \
 		   bits/libm-simd-decl-stubs.h bits/iscanonical.h \
 		   bits/flt-eval-method.h bits/fp-fast.h bits/fp-logb.h \
 		   bits/long-double.h bits/mathcalls-helper-functions.h \
-		   bits/floatn.h
+		   bits/floatn.h bits/floatn-common.h
 
 # FPU support code.
 aux		:= setfpucw fpu_control
diff --git a/sysdeps/ia64/bits/floatn.h b/sysdeps/ia64/bits/floatn.h
index dbb6eb2..a88d0f9 100644
--- a/sysdeps/ia64/bits/floatn.h
+++ b/sysdeps/ia64/bits/floatn.h
@@ -99,4 +99,6 @@ typedef __float128 _Float128;
 
 #endif
 
+#include <bits/floatn-common.h>
+
 #endif /* _BITS_FLOATN_H */
diff --git a/sysdeps/ieee754/ldbl-128/bits/floatn.h b/sysdeps/ieee754/ldbl-128/bits/floatn.h
index 5c87366..eab72cf 100644
--- a/sysdeps/ieee754/ldbl-128/bits/floatn.h
+++ b/sysdeps/ieee754/ldbl-128/bits/floatn.h
@@ -77,4 +77,6 @@ typedef long double _Float128;
 
 #endif
 
+#include <bits/floatn-common.h>
+
 #endif /* _BITS_FLOATN_H */
diff --git a/sysdeps/mips/ieee754/bits/floatn.h b/sysdeps/mips/ieee754/bits/floatn.h
index b333491..957343d 100644
--- a/sysdeps/mips/ieee754/bits/floatn.h
+++ b/sysdeps/mips/ieee754/bits/floatn.h
@@ -77,4 +77,6 @@ typedef long double _Float128;
 
 #endif
 
+#include <bits/floatn-common.h>
+
 #endif /* _BITS_FLOATN_H */
diff --git a/sysdeps/powerpc/bits/floatn.h b/sysdeps/powerpc/bits/floatn.h
index 0ce997c..44a9434 100644
--- a/sysdeps/powerpc/bits/floatn.h
+++ b/sysdeps/powerpc/bits/floatn.h
@@ -97,4 +97,6 @@ typedef __float128 _Float128;
 
 #endif
 
+#include <bits/floatn-common.h>
+
 #endif /* _BITS_FLOATN_H */
diff --git a/sysdeps/x86/bits/floatn.h b/sysdeps/x86/bits/floatn.h
index f93a9f8..5a21fd4 100644
--- a/sysdeps/x86/bits/floatn.h
+++ b/sysdeps/x86/bits/floatn.h
@@ -101,4 +101,6 @@ typedef __float128 _Float128;
 
 #endif
 
+#include <bits/floatn-common.h>
+
 #endif /* _BITS_FLOATN_H */
