Index: libelftc/Makefile
===================================================================
--- libelftc/Makefile
+++ libelftc/Makefile
@@ -10,6 +10,7 @@
 	elftc_reloc_type_str.c			\
 	elftc_set_timestamps.c			\
 	elftc_string_table.c			\
+	elftc_timestamp.c			\
 	elftc_version.c				\
 	libelftc_bfdtarget.c			\
 	libelftc_dem_arm.c			\
Index: libelftc/elftc_timestamp.3
===================================================================
--- /dev/null
+++ libelftc/elftc_timestamp.3
@@ -0,0 +1,78 @@
+.\" Copyright (c) 2016 The FreeBSD Foundation.  All rights reserved.
+.\"
+.\" This documentation was written by Ed Maste under sponsorship of
+.\" the FreeBSD Foundation.
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" This software is provided by the author and contributors ``as is'' and
+.\" any express or implied warranties, including, but not limited to, the
+.\" implied warranties of merchantability and fitness for a particular purpose
+.\" are disclaimed.  In no event shall the author or contributors be liable
+.\" for any direct, indirect, incidental, special, exemplary, or consequential
+.\" damages (including, but not limited to, procurement of substitute goods
+.\" or services; loss of use, data, or profits; or business interruption)
+.\" however caused and on any theory of liability, whether in contract, strict
+.\" liability, or tort (including negligence or otherwise) arising in any way
+.\" out of the use of this software, even if advised of the possibility of
+.\" such damage.
+.\"
+.\" $Id$
+.\"
+.Dd August 24, 2016
+.Os
+.Dt ELFTC_TIMESTAMP 3
+.Sh NAME
+.Nm elftc_timestamp
+.Nd return the current or environment-provided timestamp
+.Sh LIBRARY
+.Lb libelftc
+.Sh SYNOPSIS
+.In libelftc.h
+.Ft int
+.Fo elftc_timestamp
+.Fa "time_t *timestamp"
+.Fc
+.Sh DESCRIPTION
+The
+.Fn elftc_timestamp
+function returns a timestamp supplied by the
+.Ev SOURCE_DATE_EPOCH
+environment variable, or the current time provided by
+.Xr time 3
+if the environment variable is not set.
+.Pp
+The
+.Ar timestamp
+argument specifies a pointer to the location where the timestamp will be
+stored.
+.Sh RETURN VALUE
+Function
+.Fn elftc_timestamp
+returns 0 on success, and -1 in the event of an error.
+.Sh ERRORS
+The
+.Fn elftc_timestamp
+function may fail with the following errors:
+.Bl -tag -width ".Bq Er ERANGE"
+.It Bq Er EINVAL
+.Ev SOURCE_DATE_EPOCH
+contains invalid characters.
+.It Bq Er ERANGE
+.Ev SOURCE_DATE_EPOCH
+specifies a negative value or a value that cannot be stored in a
+time_t.
+The
+.Fn elftc_timestamp
+function may also fail for any of the reasons described in
+.Xr strtoll 3 .
+.Sh SEE ALSO
+.Xr strtoll 3 ,
+.Xr time 3
Index: libelftc/elftc_timestamp.c
===================================================================
--- /dev/null
+++ libelftc/elftc_timestamp.c
@@ -0,0 +1,55 @@
+/*-
+ * Copyright (c) 2016 The FreeBSD Foundation
+ * All rights reserved.
+ *
+ * This software was developed by Ed Maste under sponsorship
+ * of the FreeBSD Foundation.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <errno.h>
+#include <stdlib.h>
+#include <time.h>
+#include <libelftc.h>
+
+int
+elftc_timestamp(time_t *timestamp)
+{
+	long long source_date_epoch;
+	char *env, *eptr;
+
+	if ((env = getenv("SOURCE_DATE_EPOCH")) != NULL) {
+		errno = 0;
+		source_date_epoch = strtoll(env, &eptr, 10);
+		if (*eptr != '\0')
+			errno = EINVAL;
+		if (source_date_epoch < 0)
+			errno = ERANGE;
+		if (errno != 0)
+			return (-1);
+		*timestamp = source_date_epoch;
+		return (0);
+	}
+	*timestamp = time(NULL);
+	return (0);
+}
Index: libelftc/libelftc.h
===================================================================
--- libelftc/libelftc.h
+++ libelftc/libelftc.h
@@ -91,6 +91,7 @@
     const char *_string);
 const char	*elftc_string_table_to_string(Elftc_String_Table *_table,
     size_t offset);
+int		elftc_timestamp(time_t *_timestamp);
 const char	*elftc_version(void);
 #ifdef __cplusplus
 }