diff --git a/mingw-w64-crt/misc/winbs_uint64.c b/mingw-w64-crt/misc/winbs_uint64.c
index c0b3162..0158eb6 100644
--- a/mingw-w64-crt/misc/winbs_uint64.c
+++ b/mingw-w64-crt/misc/winbs_uint64.c
@@ -2,38 +2,5 @@
 
 unsigned long long __cdecl _byteswap_uint64(unsigned long long _Int64)
 {
-#if defined(_AMD64_) || defined(__x86_64__)
-  unsigned long long retval;
-  __asm__ __volatile__ ("bswapq %[retval]" : [retval] "=rm" (retval) : "[retval]" (_Int64));
-  return retval;
-#elif defined(_X86_) || defined(__i386__)
-  union {
-    long long int64part;
-    struct {
-      unsigned long lowpart;
-      unsigned long hipart;
-    };
-  } retval;
-  retval.int64part = _Int64;
-  __asm__ __volatile__ ("bswapl %[lowpart]\n"
-    "bswapl %[hipart]\n"
-    : [lowpart] "=rm" (retval.hipart), [hipart] "=rm" (retval.lowpart)  : "[lowpart]" (retval.lowpart), "[hipart]" (retval.hipart));
-  return retval.int64part;
-#else
-  unsigned char *b = (void*)&_Int64;
-  unsigned char tmp;
-  tmp = b[0];
-  b[0] = b[7];
-  b[7] = tmp;
-  tmp = b[1];
-  b[1] = b[6];
-  b[6] = tmp;
-  tmp = b[2];
-  b[2] = b[5];
-  b[5] = tmp;
-  tmp = b[3];
-  b[3] = b[4];
-  b[4] = tmp;
-  return _Int64;
-#endif
+  return __builtin_bswap64(_Int64);
 }
diff --git a/mingw-w64-crt/misc/winbs_ulong.c b/mingw-w64-crt/misc/winbs_ulong.c
index 9cd6b29..e23c113 100644
--- a/mingw-w64-crt/misc/winbs_ulong.c
+++ b/mingw-w64-crt/misc/winbs_ulong.c
@@ -2,19 +2,5 @@
 
 unsigned long __cdecl _byteswap_ulong (unsigned long _Long)
 {
-#if defined(_AMD64_) || defined(__x86_64__) || defined(_X86_) || defined(__i386__)
-  unsigned long retval;
-  __asm__ __volatile__ ("bswapl %[retval]" : [retval] "=rm" (retval) : "[retval]" (_Long));
-  return retval;
-#else
-  unsigned char *b = (void*)&_Long;
-  unsigned char tmp;
-  tmp = b[0];
-  b[0] = b[3];
-  b[3] = tmp;
-  tmp = b[1];
-  b[1] = b[2];
-  b[2] = tmp;
-  return _Long;
-#endif /* defined(_AMD64_) || defined(__x86_64__) || defined(_X86_) || defined(__i386__) */
+  return __builtin_bswap32(_Long);
 }
diff --git a/mingw-w64-crt/misc/winbs_ushort.c b/mingw-w64-crt/misc/winbs_ushort.c
index 46b57fd..b1b9ef3 100644
--- a/mingw-w64-crt/misc/winbs_ushort.c
+++ b/mingw-w64-crt/misc/winbs_ushort.c
@@ -2,16 +2,5 @@
 
 unsigned short __cdecl _byteswap_ushort(unsigned short _Short)
 {
-#if defined(_AMD64_) || defined(__x86_64__) || defined(_X86_) || defined(__i386__)
-  unsigned short retval;
-  __asm__ __volatile__ ("rorw $8, %w[retval]" : [retval] "=rm" (retval) : "[retval]" (_Short));
-  return retval;
-#else
-  unsigned char *b = (void*)&_Short;
-  unsigned char tmp;
-  tmp = b[0];
-  b[0] = b[1];
-  b[1] = tmp;
-  return _Short;
-#endif /* defined(_AMD64_) || defined(__x86_64__) || defined(_X86_) || defined(__i386__) */
+  return __builtin_bswap16(_Short);
 }