diff --git a/bits/byteswap-16.h b/bits/byteswap-16.h
deleted file mode 100644
index 0fbd8d6..0000000
--- a/bits/byteswap-16.h
+++ /dev/null
@@ -1,34 +0,0 @@
-/* Macros to swap the order of bytes in 16-bit integer values.
-   Copyright (C) 2012-2018 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_BYTESWAP_H
-# error "Never use <bits/byteswap-16.h> directly; include <byteswap.h> instead."
-#endif
-
-#ifdef __GNUC__
-# define __bswap_16(x) \
-    (__extension__							      \
-     ({ unsigned short int __bsx = (unsigned short int) (x);		      \
-       __bswap_constant_16 (__bsx); }))
-#else
-static __inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
-{
-  return __bswap_constant_16 (__bsx);
-}
-#endif
diff --git a/bits/byteswap.h b/bits/byteswap.h
index f99a6a4..23974e9 100644
--- a/bits/byteswap.h
+++ b/bits/byteswap.h
@@ -1,4 +1,4 @@
-/* Macros to swap the order of bytes in integer values.
+/* Macros and inline functions to swap the order of bytes in integer values.
    Copyright (C) 1997-2018 Free Software Foundation, Inc.
    This file is part of the GNU C Library.
 
@@ -26,87 +26,54 @@
 #include <features.h>
 #include <bits/types.h>
 
-/* Swap bytes in 16 bit value.  */
-#define __bswap_constant_16(x) \
-	((unsigned short int)((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8)))
+/* Swap bytes in 16-bit value.  */
+#define __bswap_constant_16(x)					\
+  ((__uint16_t) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
 
-/* Get __bswap_16.  */
-#include <bits/byteswap-16.h>
+static __inline __uint16_t
+__bswap_16 (__uint16_t __bsx)
+{
+#if __GNUC_PREREQ (4, 8)
+  return __builtin_bswap16 (__bsx);
+#else
+  return __bswap_constant_16 (__bsx);
+#endif
+}
 
-/* Swap bytes in 32 bit value.  */
-#define __bswap_constant_32(x) \
-     ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >>  8) |	      \
-      (((x) & 0x0000ff00u) <<  8) | (((x) & 0x000000ffu) << 24))
+/* Swap bytes in 32-bit value.  */
+#define __bswap_constant_32(x)					\
+  ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >> 8)	\
+   | (((x) & 0x0000ff00u) << 8) | (((x) & 0x000000ffu) << 24))
 
-#ifdef __GNUC__
-# if __GNUC_PREREQ (4, 3)
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
+static __inline __uint32_t
+__bswap_32 (__uint32_t __bsx)
 {
+#if __GNUC_PREREQ (4, 3)
   return __builtin_bswap32 (__bsx);
-}
-# else
-#  define __bswap_32(x) \
-  (__extension__							      \
-   ({ unsigned int __bsx = (x); __bswap_constant_32 (__bsx); }))
-# endif
 #else
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
-{
   return __bswap_constant_32 (__bsx);
-}
 #endif
+}
 
-/* Swap bytes in 64 bit value.  */
-#if __GNUC_PREREQ (2, 0)
-# define __bswap_constant_64(x) \
-     (__extension__ ((((x) & 0xff00000000000000ull) >> 56)		      \
-		     | (((x) & 0x00ff000000000000ull) >> 40)		      \
-		     | (((x) & 0x0000ff0000000000ull) >> 24)		      \
-		     | (((x) & 0x000000ff00000000ull) >> 8)		      \
-		     | (((x) & 0x00000000ff000000ull) << 8)		      \
-		     | (((x) & 0x0000000000ff0000ull) << 24)		      \
-		     | (((x) & 0x000000000000ff00ull) << 40)		      \
-		     | (((x) & 0x00000000000000ffull) << 56)))
+/* Swap bytes in 64-bit value.  */
+#define __bswap_constant_64(x)			\
+  ((((x) & 0xff00000000000000ull) >> 56)	\
+   | (((x) & 0x00ff000000000000ull) >> 40)	\
+   | (((x) & 0x0000ff0000000000ull) >> 24)	\
+   | (((x) & 0x000000ff00000000ull) >> 8)	\
+   | (((x) & 0x00000000ff000000ull) << 8)	\
+   | (((x) & 0x0000000000ff0000ull) << 24)	\
+   | (((x) & 0x000000000000ff00ull) << 40)	\
+   | (((x) & 0x00000000000000ffull) << 56))
 
-# if __GNUC_PREREQ (4, 3)
-static __inline __uint64_t
+__extension__ static __inline __uint64_t
 __bswap_64 (__uint64_t __bsx)
 {
+#if __GNUC_PREREQ (4, 3)
   return __builtin_bswap64 (__bsx);
-}
-# else
-#  define __bswap_64(x) \
-     (__extension__							      \
-      ({ union { __extension__ __uint64_t __ll;				      \
-		 unsigned int __l[2]; } __w, __r;			      \
-	 if (__builtin_constant_p (x))					      \
-	   __r.__ll = __bswap_constant_64 (x);				      \
-	 else								      \
-	   {								      \
-	     __w.__ll = (x);						      \
-	     __r.__l[0] = __bswap_32 (__w.__l[1]);			      \
-	     __r.__l[1] = __bswap_32 (__w.__l[0]);			      \
-	   }								      \
-	 __r.__ll; }))
-# endif
 #else
-# define __bswap_constant_64(x) \
-     ((((x) & 0xff00000000000000ull) >> 56)				      \
-      | (((x) & 0x00ff000000000000ull) >> 40)				      \
-      | (((x) & 0x0000ff0000000000ull) >> 24)				      \
-      | (((x) & 0x000000ff00000000ull) >> 8)				      \
-      | (((x) & 0x00000000ff000000ull) << 8)				      \
-      | (((x) & 0x0000000000ff0000ull) << 24)				      \
-      | (((x) & 0x000000000000ff00ull) << 40)				      \
-      | (((x) & 0x00000000000000ffull) << 56))
-
-static __inline __uint64_t
-__bswap_64 (__uint64_t __bsx)
-{
   return __bswap_constant_64 (__bsx);
-}
 #endif
+}
 
 #endif /* _BITS_BYTESWAP_H */
diff --git a/string/Makefile b/string/Makefile
index 1bcc9bb..680431f 100644
--- a/string/Makefile
+++ b/string/Makefile
@@ -24,7 +24,7 @@ include ../Makeconfig
 
 headers		:= string.h bits/string_fortified.h			\
 		   strings.h bits/strings_fortified.h			\
-		   byteswap.h bits/byteswap.h bits/byteswap-16.h	\
+		   byteswap.h bits/byteswap.h				\
 		   endian.h bits/endian.h bits/uintn-identity.h		\
 		   memory.h argz.h envz.h
 
@@ -58,7 +58,8 @@ tests		:= tester inl-tester noinl-tester testcopy test-ffs	\
 		   bug-strtok1 $(addprefix test-,$(strop-tests))	\
 		   bug-envz1 tst-strxfrm2 tst-endian tst-svc2		\
 		   tst-strtok_r bug-strcoll2 tst-cmp tst-xbzero-opt	\
-		   test-endian-types
+		   test-endian-types test-endian-file-scope		\
+		   test-endian-sign-conversion
 
 # This test allocates a lot of memory and can run for a long time.
 xtests = tst-strcoll-overflow
@@ -76,6 +77,7 @@ CFLAGS-stratcliff.c += -fno-builtin
 CFLAGS-test-ffs.c += -fno-builtin
 CFLAGS-tst-inlcall.c += -fno-builtin
 CFLAGS-tst-xbzero-opt.c += -O3
+CFLAGS-test-endian-sign-conversion.c += -Werror -Wsign-conversion
 # BZ 21006: Resolve all functions but at least explicit_bzero at startup.
 # Otherwise the test fails on s390x as the memcpy in prepare_test_buffer is
 # done by loading r4 / r5 with the test_pattern and using store multiple
diff --git a/string/test-endian-file-scope.c b/string/test-endian-file-scope.c
new file mode 100644
index 0000000..e03063c
--- /dev/null
+++ b/string/test-endian-file-scope.c
@@ -0,0 +1,44 @@
+/* Test endian.h endian-conversion macros accepted at file scope.
+   Copyright (C) 2018 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/>.  */
+
+#include <endian.h>
+#include <stddef.h>
+
+int i;
+
+size_t s0 = sizeof (htobe16 (i));
+size_t s1 = sizeof (htole16 (i));
+size_t s2 = sizeof (be16toh (i));
+size_t s3 = sizeof (le16toh (i));
+size_t s4 = sizeof (htobe32 (i));
+size_t s5 = sizeof (htole32 (i));
+size_t s6 = sizeof (be32toh (i));
+size_t s7 = sizeof (le32toh (i));
+size_t s8 = sizeof (htobe64 (i));
+size_t s9 = sizeof (htole64 (i));
+size_t s10 = sizeof (be64toh (i));
+size_t s11 = sizeof (le64toh (i));
+
+static int
+do_test (void)
+{
+  /* This is a compilation test.  */
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/string/test-endian-sign-conversion.c b/string/test-endian-sign-conversion.c
new file mode 100644
index 0000000..e0b13b2
--- /dev/null
+++ b/string/test-endian-sign-conversion.c
@@ -0,0 +1,48 @@
+/* Test endian.h endian-conversion macros work with -Wsign-conversion.
+   Copyright (C) 2018 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/>.  */
+
+#include <endian.h>
+#include <stdint.h>
+
+uint16_t u16;
+uint32_t u32;
+uint64_t u64;
+
+static int
+do_test (void)
+{
+  /* This is a compilation test.  */
+  u16 = (htobe16 (u16));
+  u16 = (htole16 (u16));
+  u16 = (be16toh (u16));
+  u16 = (le16toh (u16));
+  u32 = (htobe32 (u32));
+  u32 = (htole32 (u32));
+  u32 = (be32toh (u32));
+  u32 = (le32toh (u32));
+  u64 = (htobe64 (u64));
+  u64 = (htole64 (u64));
+  u64 = (be64toh (u64));
+  u64 = (le64toh (u64));
+  (void) u16;
+  (void) u32;
+  (void) u64;
+  return 0;
+}
+
+#include <support/test-driver.c>
diff --git a/sysdeps/ia64/bits/byteswap-16.h b/sysdeps/ia64/bits/byteswap-16.h
deleted file mode 100644
index 3c382c8..0000000
--- a/sysdeps/ia64/bits/byteswap-16.h
+++ /dev/null
@@ -1,42 +0,0 @@
-/* Macros to swap the order of bytes in 16-bit integer values.
-   Copyright (C) 1997-2018 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_BYTESWAP_H
-# error "Never use <bits/byteswap-16.h> directly; include <byteswap.h> instead."
-#endif
-
-#if defined __GNUC__ && __GNUC__ >= 2
-# define __bswap_16(x) \
-     (__extension__							      \
-      ({ unsigned short int __v, __x = (unsigned short int) (x);	      \
-	 if (__builtin_constant_p (x))					      \
-	   __v = __bswap_constant_16 (__x);				      \
-	 else								      \
-	   __asm__ __volatile__ ("shl %0 = %1, 48 ;;"			      \
-				 "mux1 %0 = %0, @rev ;;"		      \
-				 : "=r" (__v)				      \
-				 : "r" ((unsigned short int) (__x)));	      \
-	 __v; }))
-#else
-/* This is better than nothing.  */
-static __inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
-{
-  return __bswap_constant_16 (__bsx);
-}
-#endif
diff --git a/sysdeps/ia64/bits/byteswap.h b/sysdeps/ia64/bits/byteswap.h
deleted file mode 100644
index 553c72f..0000000
--- a/sysdeps/ia64/bits/byteswap.h
+++ /dev/null
@@ -1,100 +0,0 @@
-/* Macros to swap the order of bytes in integer values.
-   Copyright (C) 1997-2018 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/>.  */
-
-#if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H
-# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
-#endif
-
-#ifndef _BITS_BYTESWAP_H
-#define _BITS_BYTESWAP_H 1
-
-/* Swap bytes in 16 bit value.  */
-#define __bswap_constant_16(x) \
-     ((unsigned short int)((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
-
-/* Get __bswap_16.  */
-#include <bits/byteswap-16.h>
-
-/* Swap bytes in 32 bit value.  */
-#define __bswap_constant_32(x) \
-     ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |		      \
-      (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
-
-#if defined __GNUC__ && __GNUC__ >= 2
-# define __bswap_32(x) \
-     (__extension__							      \
-      ({ unsigned int __v, __x = (x);					      \
-	 if (__builtin_constant_p (x))					      \
-	   __v = __bswap_constant_32 (__x);				      \
-	 else								      \
-	   __asm__ __volatile__ ("shl %0 = %1, 32 ;;"			      \
-				 "mux1 %0 = %0, @rev ;;"		      \
-				 : "=r" (__v)				      \
-				 : "r" ((unsigned int) (__x)));		      \
-	 __v; }))
-#else
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
-{
-  return __bswap_constant_32 (__bsx);
-}
-#endif
-
-
-/* Swap bytes in 64 bit value.  */
-#if defined __GNUC__ && __GNUC__ >= 2
-# define __bswap_constant_64(x) \
-     (__extension__ ((((x) & 0xff00000000000000ul) >> 56)		      \
-		     | (((x) & 0x00ff000000000000ul) >>  40)		      \
-		     | (((x) & 0x0000ff0000000000ul) >> 24)		      \
-		     | (((x) & 0x000000ff00000000ul) >> 8)		      \
-		     | (((x) & 0x00000000ff000000ul) << 8)		      \
-		     | (((x) & 0x0000000000ff0000ul) << 24)		      \
-		     | (((x) & 0x000000000000ff00ul) << 40)		      \
-		     | (((x) & 0x00000000000000fful) << 56)))
-
-# define __bswap_64(x) \
-     (__extension__							      \
-      ({ unsigned long int __v, __x = (x);				      \
-	 if (__builtin_constant_p (x))					      \
-	   __v = __bswap_constant_64 (__x);				      \
-	 else								      \
-	   __asm__ __volatile__ ("mux1 %0 = %1, @rev ;;"		      \
-				 : "=r" (__v)				      \
-				 : "r" ((unsigned long int) (__x)));	      \
-	 __v; }))
-
-#else
-# define __bswap_constant_64(x) \
-     ((((x) & 0xff00000000000000ul) >> 56)				      \
-      | (((x) & 0x00ff000000000000ul) >>  40)				      \
-      | (((x) & 0x0000ff0000000000ul) >> 24)				      \
-      | (((x) & 0x000000ff00000000ul) >> 8)				      \
-      | (((x) & 0x00000000ff000000ul) << 8)				      \
-      | (((x) & 0x0000000000ff0000ul) << 24)				      \
-      | (((x) & 0x000000000000ff00ul) << 40)				      \
-      | (((x) & 0x00000000000000fful) << 56))
-
-static __inline unsigned long int
-__bswap_64 (unsigned long int __bsx)
-{
-  return __bswap_constant_64 (__bsx);
-}
-#endif
-
-#endif /* _BITS_BYTESWAP_H */
diff --git a/sysdeps/m68k/bits/byteswap.h b/sysdeps/m68k/bits/byteswap.h
deleted file mode 100644
index 3055230..0000000
--- a/sysdeps/m68k/bits/byteswap.h
+++ /dev/null
@@ -1,88 +0,0 @@
-/* Macros to swap the order of bytes in integer values.  m68k version.
-   Copyright (C) 1997-2018 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/>.  */
-
-#if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H
-# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
-#endif
-
-#ifndef _BITS_BYTESWAP_H
-#define _BITS_BYTESWAP_H 1
-
-/* Swap bytes in 16 bit value.  We don't provide an assembler version
-   because GCC is smart enough to generate optimal assembler output, and
-   this allows for better cse.  */
-#define __bswap_constant_16(x) \
-  ((((x) >> 8) & 0xffu) | (((x) & 0xffu) << 8))
-
-static __always_inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
-{
-  return __bswap_constant_16 (__bsx);
-}
-
-/* Swap bytes in 32 bit value.  */
-#define __bswap_constant_32(x) \
-  ((((x) & 0xff000000u) >> 24) | (((x) & 0x00ff0000u) >>  8) |		      \
-   (((x) & 0x0000ff00u) <<  8) | (((x) & 0x000000ffu) << 24))
-
-#if !defined(__mcoldfire__)
-static __always_inline unsigned int
-__bswap_32 (unsigned int __bsx)
-{
-  if (__builtin_constant_p (__bsx))
-    return __bswap_constant_32 (__bsx);
-  __asm__ __volatile__ ("ror%.w %#8, %0;"
-			"swap %0;"
-			"ror%.w %#8, %0"
-			: "+d" (__bsx));
-  return __bsx;
-}
-#else
-static __always_inline unsigned int
-__bswap_32 (unsigned int __bsx)
-{
-  return __bswap_constant_32 (__bsx);
-}
-#endif
-
-#if defined __GNUC__ && __GNUC__ >= 2
-/* Swap bytes in 64 bit value.  */
-# define __bswap_constant_64(x) \
-  __extension__								      \
-  ((((x) & 0xff00000000000000ull) >> 56)				      \
-   | (((x) & 0x00ff000000000000ull) >> 40)				      \
-   | (((x) & 0x0000ff0000000000ull) >> 24)				      \
-   | (((x) & 0x000000ff00000000ull) >> 8)				      \
-   | (((x) & 0x00000000ff000000ull) << 8)				      \
-   | (((x) & 0x0000000000ff0000ull) << 24)				      \
-   | (((x) & 0x000000000000ff00ull) << 40)				      \
-   | (((x) & 0x00000000000000ffull) << 56))
-
-/* Swap bytes in 64 bit value.  */
-__extension__
-static __always_inline unsigned long long
-__bswap_64 (unsigned long long __bsx)
-{
-  if (__builtin_constant_p (__bsx))
-    return __bswap_constant_64 (__bsx);
-  return (__bswap_32 (__bsx >> 32)
-	  | ((unsigned long long) __bswap_32 (__bsx) << 32));
-}
-#endif
-
-#endif /* _BITS_BYTESWAP_H */
diff --git a/sysdeps/s390/bits/byteswap-16.h b/sysdeps/s390/bits/byteswap-16.h
deleted file mode 100644
index d1e67d3..0000000
--- a/sysdeps/s390/bits/byteswap-16.h
+++ /dev/null
@@ -1,65 +0,0 @@
-/* Macros to swap the order of bytes in 16-bit integer values.  s390 version
-   Copyright (C) 2012-2018 Free Software Foundation, Inc.
-   Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
-   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_BYTESWAP_H
-# error "Never use <bits/byteswap-16.h> directly; include <byteswap.h> instead."
-#endif
-
-#include <bits/wordsize.h>
-
-/* Swap bytes in 16 bit value. */
-#if defined __GNUC__ && __GNUC__ >= 2
-# if __WORDSIZE == 64
-#  define __bswap_16(x) \
-     (__extension__							      \
-      ({ unsigned short int __v, __x = (unsigned short int) (x);	      \
-	 if (__builtin_constant_p (x))					      \
-	   __v = __bswap_constant_16 (__x);				      \
-	 else {								      \
-	   unsigned short int __tmp = (unsigned short int) (__x);             \
-	   __asm__ __volatile__ (                                             \
-	      "lrvh %0,%1"                                                    \
-	      : "=&d" (__v) : "m" (__tmp) );                                  \
-	 }                                                                    \
-	 __v; }))
-# else
-#  define __bswap_16(x) \
-     (__extension__							      \
-      ({ unsigned short int __v, __x = (unsigned short int) (x);	      \
-	 if (__builtin_constant_p (x))					      \
-	   __v = __bswap_constant_16 (__x);				      \
-	 else {								      \
-	   unsigned short int __tmp = (unsigned short int) (__x);             \
-	   __asm__ __volatile__ (                                             \
-	      "sr   %0,%0\n"                                                  \
-	      "la   1,%1\n"                                                   \
-	      "icm  %0,2,1(1)\n"                                              \
-	      "ic   %0,0(1)"                                                  \
-	      : "=&d" (__v) : "m" (__tmp) : "1");                             \
-	 }                                                                    \
-	 __v; }))
-# endif
-#else
-/* This is better than nothing.  */
-static __inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
-{
-  return __bswap_constant_16 (__bsx);
-}
-#endif
diff --git a/sysdeps/s390/bits/byteswap.h b/sysdeps/s390/bits/byteswap.h
deleted file mode 100644
index 79a6e5f..0000000
--- a/sysdeps/s390/bits/byteswap.h
+++ /dev/null
@@ -1,134 +0,0 @@
-/* Macros to swap the order of bytes in integer values.  s390 version.
-   Copyright (C) 2000-2018 Free Software Foundation, Inc.
-   Contributed by Martin Schwidefsky (schwidefsky@de.ibm.com).
-   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/>.  */
-
-#if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H
-# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
-#endif
-
-#include <bits/wordsize.h>
-
-#ifndef _BITS_BYTESWAP_H
-#define _BITS_BYTESWAP_H 1
-
-#define __bswap_constant_16(x) \
-	((unsigned short int) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
-
-/* Get __bswap_16.  */
-#include <bits/byteswap-16.h>
-
-/* Swap bytes in 32 bit value.  */
-#define __bswap_constant_32(x) \
-     ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |		      \
-      (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
-
-#if defined __GNUC__ && __GNUC__ >= 2
-# if __WORDSIZE == 64
-#  define __bswap_32(x) \
-     (__extension__							      \
-      ({ unsigned int __v, __x = (x);					      \
-	 if (__builtin_constant_p (x))					      \
-	   __v = __bswap_constant_32 (__x);				      \
-	 else {								      \
-	   unsigned int __tmp = (unsigned int) (__x);                         \
-	   __asm__ __volatile__ (                                             \
-	      "lrv   %0,%1"                                                   \
-	      : "=&d" (__v) : "m" (__tmp));                                   \
-	 }                                                                    \
-	 __v; }))
-# else
-#  define __bswap_32(x) \
-     (__extension__							      \
-      ({ unsigned int __v, __x = (x);					      \
-	 if (__builtin_constant_p (x))					      \
-	   __v = __bswap_constant_32 (__x);				      \
-	 else {								      \
-	   unsigned int __tmp = (unsigned int) (__x);                         \
-	   __asm__ __volatile__ (                                             \
-	      "la    1,%1\n"                                                  \
-	      "icm   %0,8,3(1)\n"                                             \
-	      "icm   %0,4,2(1)\n"                                             \
-	      "icm   %0,2,1(1)\n"                                             \
-	      "ic    %0,0(1)"                                                 \
-	      : "=&d" (__v) : "m" (__tmp) : "1");                             \
-	 }                                                                    \
-	 __v; }))
-# endif
-#else
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
-{
-  return __bswap_constant_32 (__bsx);
-}
-#endif
-
-/* Swap bytes in 64 bit value.  */
-#if defined __GNUC__ && __GNUC__ >= 2
-# define __bswap_constant_64(x) \
-     (__extension__ ((((x) & 0xff00000000000000ul) >> 56)		      \
-		     | (((x) & 0x00ff000000000000ul) >>  40)		      \
-		     | (((x) & 0x0000ff0000000000ul) >> 24)		      \
-		     | (((x) & 0x000000ff00000000ul) >> 8)		      \
-		     | (((x) & 0x00000000ff000000ul) << 8)		      \
-		     | (((x) & 0x0000000000ff0000ul) << 24)		      \
-		     | (((x) & 0x000000000000ff00ul) << 40)		      \
-		     | (((x) & 0x00000000000000fful) << 56)))
-
-# if __WORDSIZE == 64
-#  define __bswap_64(x) \
-     (__extension__							      \
-      ({ unsigned long __w, __x = (x);					      \
-	 if (__builtin_constant_p (x))					      \
-	   __w = __bswap_constant_64 (__x);				      \
-	 else {								      \
-	   unsigned long __tmp = (unsigned long) (__x);                       \
-	   __asm__ __volatile__ (                                             \
-	      "lrvg  %0,%1"                                                   \
-	      : "=&d" (__w) : "m" (__tmp));                                   \
-	 }                                                                    \
-	 __w; }))
-# else
-#  define __bswap_64(x) \
-     __extension__					\
-       ({ union { unsigned long long int __ll;		\
-		  unsigned long int __l[2]; } __w, __r;	\
-	  __w.__ll = (x);				\
-	  __r.__l[0] = __bswap_32 (__w.__l[1]);		\
-	  __r.__l[1] = __bswap_32 (__w.__l[0]);		\
-	  __r.__ll; })
-# endif
-#else
-# define __bswap_constant_64(x) \
-     ((((x) & 0xff00000000000000ull) >> 56)				      \
-      | (((x) & 0x00ff000000000000ull) >> 40)				      \
-      | (((x) & 0x0000ff0000000000ull) >> 24)				      \
-      | (((x) & 0x000000ff00000000ull) >> 8)				      \
-      | (((x) & 0x00000000ff000000ull) << 8)				      \
-      | (((x) & 0x0000000000ff0000ull) << 24)				      \
-      | (((x) & 0x000000000000ff00ull) << 40)				      \
-      | (((x) & 0x00000000000000ffull) << 56))
-
-__extension__
-static __inline unsigned long long int
-__bswap_64 (unsigned long long int __bsx)
-{
-  return __bswap_constant_64 (__bsx);
-}
-#endif
-
-#endif /* _BITS_BYTESWAP_H */
diff --git a/sysdeps/tile/bits/byteswap.h b/sysdeps/tile/bits/byteswap.h
deleted file mode 100644
index ab36055..0000000
--- a/sysdeps/tile/bits/byteswap.h
+++ /dev/null
@@ -1,37 +0,0 @@
-/* Copyright (C) 2011-2018 Free Software Foundation, Inc.
-   This file is part of the GNU C Library.
-   Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
-
-   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/>.  */
-
-#if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H
-# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
-#endif
-
-#ifndef _BITS_BYTESWAP_H
-#define _BITS_BYTESWAP_H 1
-
-#include <bits/types.h>
-
-/* gcc __builtin_bswap64() can constant-fold, etc, so always use it. */
-#define __bswap_16(x) ((unsigned short)(__builtin_bswap32(x) >> 16))
-#define __bswap_32(x) ((unsigned int)__builtin_bswap32(x))
-#define __bswap_64(x) ((__uint64_t)__builtin_bswap64(x))
-
-#define __bswap_constant_16(x) __bswap_16(x)
-#define __bswap_constant_32(x) __bswap_32(x)
-#define __bswap_constant_64(x) __bswap_64(x)
-
-#endif /* _BITS_BYTESWAP_H */
diff --git a/sysdeps/x86/bits/byteswap-16.h b/sysdeps/x86/bits/byteswap-16.h
deleted file mode 100644
index 34af790..0000000
--- a/sysdeps/x86/bits/byteswap-16.h
+++ /dev/null
@@ -1,49 +0,0 @@
-/* Macros to swap the order of bytes in 16-bit integer values.
-   Copyright (C) 2012-2018 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_BYTESWAP_H
-# error "Never use <bits/byteswap-16.h> directly; include <byteswap.h> instead."
-#endif
-
-#ifdef __GNUC__
-# if __GNUC__ >= 2
-#  define __bswap_16(x) \
-     (__extension__							      \
-      ({ unsigned short int __v, __x = (unsigned short int) (x);	      \
-	 if (__builtin_constant_p (__x))				      \
-	   __v = __bswap_constant_16 (__x);				      \
-	 else								      \
-	   __asm__ ("rorw $8, %w0"					      \
-		    : "=r" (__v)					      \
-		    : "0" (__x)						      \
-		    : "cc");						      \
-	 __v; }))
-# else
-/* This is better than nothing.  */
-#  define __bswap_16(x) \
-     (__extension__							      \
-      ({ unsigned short int __x = (unsigned short int) (x);		      \
-	 __bswap_constant_16 (__x); }))
-# endif
-#else
-static __inline unsigned short int
-__bswap_16 (unsigned short int __bsx)
-{
-  return __bswap_constant_16 (__bsx);
-}
-#endif
diff --git a/sysdeps/x86/bits/byteswap.h b/sysdeps/x86/bits/byteswap.h
deleted file mode 100644
index 23c8f42..0000000
--- a/sysdeps/x86/bits/byteswap.h
+++ /dev/null
@@ -1,155 +0,0 @@
-/* Macros to swap the order of bytes in integer values.
-   Copyright (C) 1997-2018 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/>.  */
-
-#if !defined _BYTESWAP_H && !defined _NETINET_IN_H && !defined _ENDIAN_H
-# error "Never use <bits/byteswap.h> directly; include <byteswap.h> instead."
-#endif
-
-#ifndef _BITS_BYTESWAP_H
-#define _BITS_BYTESWAP_H 1
-
-#include <features.h>
-#include <bits/types.h>
-#include <bits/wordsize.h>
-
-/* Swap bytes in 16 bit value.  */
-#define __bswap_constant_16(x) \
-     ((unsigned short int) ((((x) >> 8) & 0xff) | (((x) & 0xff) << 8)))
-
-/* Get __bswap_16.  */
-#include <bits/byteswap-16.h>
-
-/* Swap bytes in 32 bit value.  */
-#define __bswap_constant_32(x) \
-     ((((x) & 0xff000000) >> 24) | (((x) & 0x00ff0000) >>  8) |		      \
-      (((x) & 0x0000ff00) <<  8) | (((x) & 0x000000ff) << 24))
-
-#ifdef __GNUC__
-# if __GNUC_PREREQ (4, 3)
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
-{
-  return __builtin_bswap32 (__bsx);
-}
-# elif __GNUC__ >= 2
-#  if __WORDSIZE == 64 || (defined __i486__ || defined __pentium__	      \
-			   || defined __pentiumpro__ || defined __pentium4__  \
-			   || defined __k8__ || defined __athlon__	      \
-			   || defined __k6__ || defined __nocona__	      \
-			   || defined __core2__ || defined __geode__	      \
-			   || defined __amdfam10__)
-/* To swap the bytes in a word the i486 processors and up provide the
-   `bswap' opcode.  On i386 we have to use three instructions.  */
-#   define __bswap_32(x) \
-      (__extension__							      \
-       ({ unsigned int __v, __x = (x);					      \
-	  if (__builtin_constant_p (__x))				      \
-	    __v = __bswap_constant_32 (__x);				      \
-	  else								      \
-	    __asm__ ("bswap %0" : "=r" (__v) : "0" (__x));		      \
-	  __v; }))
-#  else
-#   define __bswap_32(x)						      \
-      (__extension__							      \
-       ({ unsigned int __v, __x = (x);					      \
-	  if (__builtin_constant_p (__x))				      \
-	    __v = __bswap_constant_32 (__x);				      \
-	  else								      \
-	    __asm__ ("rorw $8, %w0;"					      \
-		     "rorl $16, %0;"					      \
-		     "rorw $8, %w0"					      \
-		     : "=r" (__v)					      \
-		     : "0" (__x)					      \
-		     : "cc");						      \
-	  __v; }))
-#  endif
-# else
-#  define __bswap_32(x) \
-     (__extension__							      \
-      ({ unsigned int __x = (x); __bswap_constant_32 (__x); }))
-# endif
-#else
-static __inline unsigned int
-__bswap_32 (unsigned int __bsx)
-{
-  return __bswap_constant_32 (__bsx);
-}
-#endif
-
-
-#if __GNUC_PREREQ (2, 0)
-/* Swap bytes in 64 bit value.  */
-# define __bswap_constant_64(x) \
-     (__extension__ ((((x) & 0xff00000000000000ull) >> 56)		      \
-		     | (((x) & 0x00ff000000000000ull) >> 40)		      \
-		     | (((x) & 0x0000ff0000000000ull) >> 24)		      \
-		     | (((x) & 0x000000ff00000000ull) >> 8)		      \
-		     | (((x) & 0x00000000ff000000ull) << 8)		      \
-		     | (((x) & 0x0000000000ff0000ull) << 24)		      \
-		     | (((x) & 0x000000000000ff00ull) << 40)		      \
-		     | (((x) & 0x00000000000000ffull) << 56)))
-
-# if __GNUC_PREREQ (4, 3)
-static __inline __uint64_t
-__bswap_64 (__uint64_t __bsx)
-{
-  return __builtin_bswap64 (__bsx);
-}
-# elif __WORDSIZE == 64
-#  define __bswap_64(x) \
-     (__extension__							      \
-      ({ __uint64_t __v, __x = (x);					      \
-	 if (__builtin_constant_p (__x))				      \
-	   __v = __bswap_constant_64 (__x);				      \
-	 else								      \
-	   __asm__ ("bswap %q0" : "=r" (__v) : "0" (__x));		      \
-	 __v; }))
-# else
-#  define __bswap_64(x) \
-     (__extension__                                                           \
-      ({ union { __extension__ __uint64_t __ll;		                      \
-		 unsigned int __l[2]; } __w, __r;                             \
-	 if (__builtin_constant_p (x))                                        \
-	   __r.__ll = __bswap_constant_64 (x);                                \
-	 else                                                                 \
-	   {                                                                  \
-	     __w.__ll = (x);                                                  \
-	     __r.__l[0] = __bswap_32 (__w.__l[1]);                            \
-	     __r.__l[1] = __bswap_32 (__w.__l[0]);                            \
-	   }                                                                  \
-	 __r.__ll; }))
-# endif
-#else
-# define __bswap_constant_64(x) \
-     ((((x) & 0xff00000000000000ull) >> 56)				      \
-      | (((x) & 0x00ff000000000000ull) >> 40)				      \
-      | (((x) & 0x0000ff0000000000ull) >> 24)				      \
-      | (((x) & 0x000000ff00000000ull) >> 8)				      \
-      | (((x) & 0x00000000ff000000ull) << 8)				      \
-      | (((x) & 0x0000000000ff0000ull) << 24)				      \
-      | (((x) & 0x000000000000ff00ull) << 40)				      \
-      | (((x) & 0x00000000000000ffull) << 56))
-
-static __inline __uint64_t
-__bswap_64 (__uint64_t __bsx)
-{
-  return __bswap_constant_64 (__bsx);
-}
-#endif
-
-#endif /* _BITS_BYTESWAP_H */
