diff --git a/bits/timesize.h b/bits/timesize.h
new file mode 100644
index 0000000000..0739a34df4
--- /dev/null
+++ b/bits/timesize.h
@@ -0,0 +1,23 @@
+/* Bit size of the time_t type at glibc build time, general case.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   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 <bits/wordsize.h>
+
+/* Size in bits of the 'time_t' type.  */
+#define __TIMESIZE	__WORDSIZE
diff --git a/bits/timesizes.h b/bits/timesizes.h
new file mode 100644
index 0000000000..0bbbfca8ff
--- /dev/null
+++ b/bits/timesizes.h
@@ -0,0 +1,37 @@
+/* bits/timesizes.h -- underlying types for __time64_t.  Generic version.
+   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/>.  */
+
+#ifndef _BITS_TYPES_H
+# error "Never include <bits/timesizes.h> directly; use <sys/types.h> instead."
+#endif
+
+#ifndef	_BITS_TIMESIZES_H
+#define	_BITS_TIMESIZES_H	1
+
+/* See <bits/types.h> for the meaning of these macros.  This file exists so
+   that <bits/types.h> need not vary across different GNU platforms.  */
+
+#if __TIMESIZE == 64
+/* If we already have 64-bit time then use it.  */
+# define __TIME64_T_TYPE		__TIME_T_TYPE
+#else
+/* Define a 64-bit type alongsize the 32-bit one.  */
+# define __TIME64_T_TYPE		__SQUAD_TYPE
+#endif
+
+#endif /* bits/timesizes.h */
diff --git a/include/time.h b/include/time.h
index 23d2580528..a311d30d53 100644
--- a/include/time.h
+++ b/include/time.h
@@ -3,6 +3,7 @@
 
 #ifndef _ISOMAC
 # include <bits/types/locale_t.h>
+# include <stdbool.h>
 
 extern __typeof (strftime_l) __strftime_l;
 libc_hidden_proto (__strftime_l)
@@ -26,10 +27,6 @@ extern __typeof (clock_getcpuclockid) __clock_getcpuclockid;
 /* Now define the internal interfaces.  */
 struct tm;
 
-/* time_t variant for representing time zone data, independent of
-   time_t.  */
-typedef __int64_t internal_time_t;
-
 /* Defined in mktime.c.  */
 extern const unsigned short int __mon_yday[2][13] attribute_hidden;
 
@@ -43,7 +40,7 @@ extern int __use_tzfile attribute_hidden;
 
 extern void __tzfile_read (const char *file, size_t extra,
 			   char **extrap) attribute_hidden;
-extern void __tzfile_compute (internal_time_t timer, int use_localtime,
+extern void __tzfile_compute (__time64_t timer, int use_localtime,
 			      long int *leap_correct, int *leap_hit,
 			      struct tm *tp) attribute_hidden;
 extern void __tzfile_default (const char *std, const char *dst,
@@ -101,7 +98,6 @@ extern char * __strptime_internal (const char *rp, const char *fmt,
 
 extern double __difftime (time_t time1, time_t time0);
 
-
 /* Use in the clock_* functions.  Size of the field representing the
    actual clock ID.  */
 #define CLOCK_IDFIELD_SIZE	3
diff --git a/posix/bits/types.h b/posix/bits/types.h
index 5e22ce41bf..66ccb0a6bc 100644
--- a/posix/bits/types.h
+++ b/posix/bits/types.h
@@ -25,6 +25,7 @@
 
 #include <features.h>
 #include <bits/wordsize.h>
+#include <bits/timesize.h>
 
 /* Convenience types.  */
 typedef unsigned char __u_char;
@@ -138,6 +139,7 @@ __extension__ typedef unsigned long long int __uintmax_t;
 # error
 #endif
 #include <bits/typesizes.h>	/* Defines __*_T_TYPE macros.  */
+#include <bits/timesizes.h>	/* Defines __TIME*_T_TYPE macros.  */
 
 
 __STD_TYPE __DEV_T_TYPE __dev_t;	/* Type of device numbers.  */
@@ -211,6 +213,12 @@ __STD_TYPE __U32_TYPE __socklen_t;
    It is not currently necessary for this to be machine-specific.  */
 typedef int __sig_atomic_t;
 
+#if __TIMESIZE == 64
+# define __time64_t __time_t
+#else
+__STD_TYPE __TIME64_T_TYPE __time64_t;	/* Seconds since the Epoch (_TIME_BITS==64).  */
+#endif
+
 #undef __STD_TYPE
 
 #endif /* bits/types.h */
diff --git a/stdlib/Makefile b/stdlib/Makefile
index 808a8ceab7..c6ef3c8d06 100644
--- a/stdlib/Makefile
+++ b/stdlib/Makefile
@@ -29,7 +29,7 @@ headers	:= stdlib.h bits/stdlib.h bits/stdlib-ldbl.h bits/stdlib-float.h      \
 	   ucontext.h sys/ucontext.h					      \
 	   alloca.h fmtmsg.h						      \
 	   bits/stdlib-bsearch.h sys/random.h bits/stdint-intn.h	      \
-	   bits/stdint-uintn.h
+	   bits/stdint-uintn.h bits/timesizes.h bits/timesize.h		      \
 
 routines	:=							      \
 	atof atoi atol atoll						      \
diff --git a/sysdeps/unix/sysv/linux/x86/bits/timesize.h b/sysdeps/unix/sysv/linux/x86/bits/timesize.h
new file mode 100644
index 0000000000..f8fe3929bc
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/bits/timesize.h
@@ -0,0 +1,26 @@
+/* Bit size of the time_t type at glibc build time, x86-64 and x32 case.
+   Copyright (C) 2018 Free Software Foundation, Inc.
+   This file is part of the GNU C Library.
+   Contributed by Ulrich Drepper <drepper@redhat.com>, 2002.
+
+   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 __x86_64__ && defined __ILP32__
+/* For x32, time is 64-bit even though word size is 32-bit.  */
+# define __TIMESIZE	64
+#else
+/* For others, time size is word size.  */
+# define __TIMESIZE	__WORDSIZE
+#endif
diff --git a/sysdeps/unix/sysv/linux/x86/bits/timesizes.h b/sysdeps/unix/sysv/linux/x86/bits/timesizes.h
new file mode 100644
index 0000000000..6132ec86ab
--- /dev/null
+++ b/sysdeps/unix/sysv/linux/x86/bits/timesizes.h
@@ -0,0 +1,40 @@
+/* bits/typesizes.h -- underlying types for __time64_t.  Linux/x86-64 version.
+   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/>.  */
+
+#ifndef _BITS_TYPES_H
+# error "Never include <bits/timesizes.h> directly; use <sys/types.h> instead."
+#endif
+
+#ifndef	_BITS_TIMESIZES_H
+#define	_BITS_TIMESIZES_H	1
+
+/* See <bits/types.h> for the meaning of these macros.  This file exists so
+   that <bits/types.h> need not vary across different GNU platforms.  */
+
+#if defined __x86_64__ && defined __ILP32__
+/* For x32, time is 64-bit even though word size is 32-bit.  */
+# define __TIME64_T_TYPE		__SQUAD_TYPE
+#elif __TIMESIZE == 64
+/* If we already have 64-bit time then use it.  */
+# define __TIME64_T_TYPE		__TIME_T_TYPE
+#else
+/* Define a 64-bit type alongsize the 32-bit one.  */
+# define __TIME64_T_TYPE		__SQUAD_TYPE
+#endif
+
+#endif /* bits/timesizes.h */
diff --git a/time/tzfile.c b/time/tzfile.c
index 2a385b92bc..d7e391c3a3 100644
--- a/time/tzfile.c
+++ b/time/tzfile.c
@@ -44,12 +44,12 @@ struct ttinfo
 
 struct leap
   {
-    internal_time_t transition;	/* Time the transition takes effect.  */
+    __time64_t transition;	/* Time the transition takes effect.  */
     long int change;		/* Seconds of correction to apply.  */
   };
 
 static size_t num_transitions;
-libc_freeres_ptr (static internal_time_t *transitions);
+libc_freeres_ptr (static __time64_t *transitions);
 static unsigned char *type_idxs;
 static size_t num_types;
 static struct ttinfo *types;
@@ -113,8 +113,8 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
   size_t tzspec_len;
   char *new = NULL;
 
-  _Static_assert (sizeof (internal_time_t) == 8,
-		  "internal_time_t must be eight bytes");
+  _Static_assert (sizeof (__time64_t) == 8,
+		  "__time64_t must be eight bytes");
 
   __use_tzfile = 0;
 
@@ -220,9 +220,9 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
 
   if (__builtin_expect (num_transitions
 			> ((SIZE_MAX - (__alignof__ (struct ttinfo) - 1))
-			   / (sizeof (internal_time_t) + 1)), 0))
+			   / (sizeof (__time64_t) + 1)), 0))
     goto lose;
-  total_size = num_transitions * (sizeof (internal_time_t) + 1);
+  total_size = num_transitions * (sizeof (__time64_t) + 1);
   total_size = ((total_size + __alignof__ (struct ttinfo) - 1)
 		& ~(__alignof__ (struct ttinfo) - 1));
   types_idx = total_size;
@@ -279,7 +279,7 @@ __tzfile_read (const char *file, size_t extra, char **extrap)
     goto lose;
 
   type_idxs = (unsigned char *) transitions + (num_transitions
-					       * sizeof (internal_time_t));
+					       * sizeof (__time64_t));
   types = (struct ttinfo *) ((char *) transitions + types_idx);
   zone_names = (char *) types + num_types * sizeof (struct ttinfo);
   leaps = (struct leap *) ((char *) transitions + leaps_idx);
@@ -580,7 +580,7 @@ __tzfile_default (const char *std, const char *dst,
 }
 
 void
-__tzfile_compute (internal_time_t timer, int use_localtime,
+__tzfile_compute (__time64_t timer, int use_localtime,
 		  long int *leap_correct, int *leap_hit,
 		  struct tm *tp)
 {
@@ -669,7 +669,7 @@ __tzfile_compute (internal_time_t timer, int use_localtime,
 	     initial search spot from it.  Half of a gregorian year
 	     has on average 365.2425 * 86400 / 2 = 15778476 seconds.
 	     The value i can be truncated if size_t is smaller than
-	     internal_time_t, but this is harmless because it is just
+	     __time64_t, but this is harmless because it is just
 	     a guess.  */
 	  i = (transitions[num_transitions - 1] - timer) / 15778476;
 	  if (i < num_transitions)
