diff --git a/Documentation/git-gc.txt b/Documentation/git-gc.txt
index b370b025b8..2402ed6828 100644
--- a/Documentation/git-gc.txt
+++ b/Documentation/git-gc.txt
@@ -62,8 +62,9 @@ automatic consolidation of packs.
 
 --prune=<date>::
 	Prune loose objects older than date (default is 2 weeks ago,
-	overridable by the config variable `gc.pruneExpire`).  This
-	option is on by default.
+	overridable by the config variable `gc.pruneExpire`).
+	--prune=all prunes loose objects regardless of their age.
+	--prune is on by default.
 
 --no-prune::
 	Do not prune any loose objects.
diff --git a/Documentation/git-reflog.txt b/Documentation/git-reflog.txt
index fb8697ea4c..70791b9fd8 100644
--- a/Documentation/git-reflog.txt
+++ b/Documentation/git-reflog.txt
@@ -67,14 +67,19 @@ them.
 --expire=<time>::
 	Entries older than this time are pruned.  Without the
 	option it is taken from configuration `gc.reflogExpire`,
-	which in turn defaults to 90 days.
+	which in turn defaults to 90 days.  --expire=all prunes
+	entries regardless of their age; --expire=never turns off
+	pruning of reachable entries (but see --expire-unreachable).
 
 --expire-unreachable=<time>::
 	Entries older than this time and not reachable from
 	the current tip of the branch are pruned.  Without the
 	option it is taken from configuration
 	`gc.reflogExpireUnreachable`, which in turn defaults to
-	30 days.
+	30 days.  --expire-unreachable=all prunes unreachable
+	entries regardless of their age; --expire-unreachable=never
+	turns off early pruning of unreachable entries (but see
+	--expire).
 
 --all::
 	Instead of listing <refs> explicitly, prune all refs.
diff --git a/Documentation/technical/api-parse-options.txt b/Documentation/technical/api-parse-options.txt
index 32ddc1cf13..1317db4d6c 100644
--- a/Documentation/technical/api-parse-options.txt
+++ b/Documentation/technical/api-parse-options.txt
@@ -41,6 +41,8 @@ The parse-options API allows:
 * Boolean long options can be 'negated' (or 'unset') by prepending
   `no-`, e.g. `--no-abbrev` instead of `--abbrev`. Conversely,
   options that begin with `no-` can be 'negated' by removing it.
+  Other long options can be unset (e.g., set string to NULL, set
+  integer to 0) by prepending `no-`.
 
 * Options and non-option arguments can clearly be separated using the `--`
   option, e.g. `-a -b --option -- --this-is-a-file` indicates that
@@ -174,6 +176,10 @@ There are some macros to easily define options:
 	Introduce an option with date argument, see `approxidate()`.
 	The timestamp is put into `int_var`.
 
+`OPT_EXPIRY_DATE(short, long, &int_var, description)`::
+	Introduce an option with expiry date argument, see `parse_expiry_date()`.
+	The timestamp is put into `int_var`.
+
 `OPT_CALLBACK(short, long, &var, arg_str, description, func_ptr)`::
 	Introduce an option with argument.
 	The argument will be fed into the function given by `func_ptr`
diff --git a/builtin/prune.c b/builtin/prune.c
index 85843d4f17..b90e5cc361 100644
--- a/builtin/prune.c
+++ b/builtin/prune.c
@@ -132,8 +132,8 @@ int cmd_prune(int argc, const char **argv, const char *prefix)
 		OPT__DRY_RUN(&show_only, N_("do not remove, show only")),
 		OPT__VERBOSE(&verbose, N_("report pruned objects")),
 		OPT_BOOL(0, "progress", &show_progress, N_("show progress")),
-		OPT_DATE(0, "expire", &expire,
-			 N_("expire objects older than <time>")),
+		OPT_EXPIRY_DATE(0, "expire", &expire,
+				N_("expire objects older than <time>")),
 		OPT_END()
 	};
 	char *s;
diff --git a/builtin/reflog.c b/builtin/reflog.c
index 72a0af70c3..54184b3d13 100644
--- a/builtin/reflog.c
+++ b/builtin/reflog.c
@@ -496,11 +496,9 @@ static int parse_expire_cfg_value(const char *var, const char *value, unsigned l
 {
 	if (!value)
 		return config_error_nonbool(var);
-	if (!strcmp(value, "never") || !strcmp(value, "false")) {
-		*expire = 0;
-		return 0;
-	}
-	*expire = approxidate(value);
+	if (parse_expiry_date(value, expire))
+		return error(_("%s' for '%s' is not a valid timestamp"),
+			     value, var);
 	return 0;
 }
 
@@ -614,11 +612,13 @@ static int cmd_reflog_expire(int argc, const char **argv, const char *prefix)
 		if (!strcmp(arg, "--dry-run") || !strcmp(arg, "-n"))
 			cb.dry_run = 1;
 		else if (!prefixcmp(arg, "--expire=")) {
-			cb.expire_total = approxidate(arg + 9);
+			if (parse_expiry_date(arg + 9, &cb.expire_total))
+				die(_("'%s' is not a valid timestamp"), arg);
 			explicit_expiry |= EXPIRE_TOTAL;
 		}
 		else if (!prefixcmp(arg, "--expire-unreachable=")) {
-			cb.expire_unreachable = approxidate(arg + 21);
+			if (parse_expiry_date(arg + 21, &cb.expire_unreachable))
+				die(_("'%s' is not a valid timestamp"), arg);
 			explicit_expiry |= EXPIRE_UNREACH;
 		}
 		else if (!strcmp(arg, "--stale-fix"))
diff --git a/cache.h b/cache.h
index 94ca1acf70..7ce9061137 100644
--- a/cache.h
+++ b/cache.h
@@ -910,6 +910,7 @@ void show_date_relative(unsigned long time, int tz, const struct timeval *now,
 			struct strbuf *timebuf);
 int parse_date(const char *date, char *buf, int bufsize);
 int parse_date_basic(const char *date, unsigned long *timestamp, int *offset);
+int parse_expiry_date(const char *date, unsigned long *timestamp);
 void datestamp(char *buf, int bufsize);
 #define approxidate(s) approxidate_careful((s), NULL)
 unsigned long approxidate_careful(const char *, int *);
diff --git a/date.c b/date.c
index df20d0ba1d..29f15404fe 100644
--- a/date.c
+++ b/date.c
@@ -711,6 +711,28 @@ int parse_date_basic(const char *date, unsigned long *timestamp, int *offset)
 	return 0; /* success */
 }
 
+int parse_expiry_date(const char *date, unsigned long *timestamp)
+{
+	int errors = 0;
+
+	if (!strcmp(date, "never") || !strcmp(date, "false"))
+		*timestamp = 0;
+	else if (!strcmp(date, "all") || !strcmp(date, "now"))
+		/*
+		 * We take over "now" here, which usually translates
+		 * to the current timestamp.  This is because the user
+		 * really means to expire everything she has done in
+		 * the past, and by definition reflogs are the record
+		 * of the past, and there is nothing from the future
+		 * to be kept.
+		 */
+		*timestamp = ULONG_MAX;
+	else
+		*timestamp = approxidate_careful(date, &errors);
+
+	return errors;
+}
+
 int parse_date(const char *date, char *result, int maxlen)
 {
 	unsigned long timestamp;
diff --git a/parse-options-cb.c b/parse-options-cb.c
index 0de5fb168a..be8c413cfe 100644
--- a/parse-options-cb.c
+++ b/parse-options-cb.c
@@ -33,6 +33,12 @@ int parse_opt_approxidate_cb(const struct option *opt, const char *arg,
 	return 0;
 }
 
+int parse_opt_expiry_date_cb(const struct option *opt, const char *arg,
+			     int unset)
+{
+	return parse_expiry_date(arg, (unsigned long *)opt->value);
+}
+
 int parse_opt_color_flag_cb(const struct option *opt, const char *arg,
 			    int unset)
 {
diff --git a/parse-options.h b/parse-options.h
index 1c8bd8d5a0..c378b75b13 100644
--- a/parse-options.h
+++ b/parse-options.h
@@ -140,6 +140,9 @@ struct option {
 #define OPT_DATE(s, l, v, h) \
 	{ OPTION_CALLBACK, (s), (l), (v), N_("time"),(h), 0,	\
 	  parse_opt_approxidate_cb }
+#define OPT_EXPIRY_DATE(s, l, v, h) \
+	{ OPTION_CALLBACK, (s), (l), (v), N_("expiry date"),(h), 0,	\
+	  parse_opt_expiry_date_cb }
 #define OPT_CALLBACK(s, l, v, a, h, f) \
 	{ OPTION_CALLBACK, (s), (l), (v), (a), (h), 0, (f) }
 #define OPT_NUMBER_CALLBACK(v, h, f) \
@@ -219,6 +222,7 @@ extern int parse_options_concat(struct option *dst, size_t, struct option *src);
 /*----- some often used options -----*/
 extern int parse_opt_abbrev_cb(const struct option *, const char *, int);
 extern int parse_opt_approxidate_cb(const struct option *, const char *, int);
+extern int parse_opt_expiry_date_cb(const struct option *, const char *, int);
 extern int parse_opt_color_flag_cb(const struct option *, const char *, int);
 extern int parse_opt_verbosity_cb(const struct option *, const char *, int);
 extern int parse_opt_with_commit(const struct option *, const char *, int);