diff --git a/doc/lightningd-config.5 b/doc/lightningd-config.5
index 8292a2541..971d123e3 100644
--- a/doc/lightningd-config.5
+++ b/doc/lightningd-config.5
@@ -14,8 +14,8 @@ directory (if it exists), but that can be changed by the
 
 
 Configuration file options are processed first, then command line
-options: later options override earlier ones except \fIaddr\fR options which
-accumulate\.
+options: later options override earlier ones except \fIaddr\fR options 
+and \fIlog-level\fR with subsystems, which accumulate\.
 
 
 All these options are mirrored as commandline arguments to
@@ -119,30 +119,69 @@ Sets the working directory\. All files (except \fI--conf\fR and
 Specify pid file to write to\.
 
 
- \fBlog-level\fR=\fILEVEL\fR
+ \fBlog-level\fR=\fILEVEL\fR[:\fISUBSYSTEM\fR]
 What log level to print out: options are io, debug, info, unusual,
-broken\.
+broken\.  If \fISUBSYSTEM\fR is supplied, this sets the logging level
+for any subsystem containing that string\.  Subsystems include:
+
+.RS
+.IP \[bu]
+\fIlightningd\fR: The main lightning daemon
+.IP \[bu]
+\fIdatabase\fR: The database subsystem
+.IP \[bu]
+\fIwallet\fR: The wallet subsystem
+.IP \[bu]
+\fIgossipd\fR: The gossip daemon
+.IP \[bu]
+\fIplugin-manager\fR: The plugin subsystem
+.IP \[bu]
+\fIplugin-P\fR: Each plugin, P = plugin path without directory
+.IP \[bu]
+\fIhsmd\fR: The secret-holding daemon
+.IP \[bu]
+\fIgossipd\fR: The gossip daemon
+.IP \[bu]
+\fIconnectd\fR: The network connection daemon
+
+.RE
+
+The following subsystems exist for each channel, where N is an incrementing
+internal integer id assigned for the lifetime of the channel:
+
+.RS
+.IP \[bu]
+\fIopeningd-chan #N\fR: Each opening / idling daemon
+.IP \[bu]
+\fIchanneld-chan #N\fR: Each channel management daemon
+.IP \[bu]
+\fIclosingd-chan #N\fR: Each closing negotiation daemon
+.IP \[bu]
+\fIonchaind-chan #N\fR: Each onchain close handling daemon
+.IP \[bu]
+
+\fIjson #FD\fR: Each JSONRPC connection, FD = file descriptor number
 
 
- \fBlog-prefix\fR=\fIPREFIX\fR
+\fBlog-prefix\fR=\fIPREFIX\fR
 Prefix for log lines: this can be customized if you want to merge logs
 with multiple daemons\.
 
 
- \fBlog-file\fR=\fIPATH\fR
+\fBlog-file\fR=\fIPATH\fR
 Log to this file instead of stdout\. Sending \fBlightningd\fR(8) SIGHUP will
 cause it to reopen this file (useful for log rotation)\.
 
 
- \fBrpc-file\fR=\fIPATH\fR
+\fBrpc-file\fR=\fIPATH\fR
 Set JSON-RPC socket (or /dev/tty), such as for \fBlightning-cli\fR(1)\.
 
 
- \fBdaemon\fR
+\fBdaemon\fR
 Run in the background, suppress stdout and stderr\.
 
 
- \fBconf\fR=\fIPATH\fR
+\fBconf\fR=\fIPATH\fR
 Sets configuration file (default: \fBlightning-dir\fR/\fIconfig\fR )\. If this
 is a relative path, it is relative to the starting directory, not
 \fBlightning-dir\fR (unlike other paths)\. \fIPATH\fR must exist and be
@@ -150,17 +189,20 @@ readable (we allow missing files in the default case)\. Using this inside
 a configuration file is meaningless\.
 
 
- \fBwallet\fR=\fIDSN\fR
+\fBwallet\fR=\fIDSN\fR
 Identify the location of the wallet\. This is a fully qualified data source
 name, including a scheme such as \fBsqlite3\fR or \fBpostgres\fR followed by the
 connection parameters\.
 
 
- \fBencrypted-hsm\fR
+\fBencrypted-hsm\fR
 If set, you will be prompted to enter a password used to encrypt the \fBhsm_secret\fR\.
 Note that once you encrypt the \fBhsm_secret\fR this option will be mandatory for
 \fBlightningd\fR to start\.
 
+
+
+.RE
 .SH Lightning node customization options
 
  \fBalias\fR=\fIRRGGBB\fR
diff --git a/doc/lightningd-config.5.md b/doc/lightningd-config.5.md
index 4d0b14e5d..ceed157a8 100644
--- a/doc/lightningd-config.5.md
+++ b/doc/lightningd-config.5.md
@@ -15,8 +15,8 @@ directory (if it exists), but that can be changed by the
 *--lightning-dir* or *--conf* options on the lightningd(8) command line.
 
 Configuration file options are processed first, then command line
-options: later options override earlier ones except *addr* options which
-accumulate.
+options: later options override earlier ones except *addr* options 
+and *log-level* with subsystems, which accumulate.
 
 All these options are mirrored as commandline arguments to
 lightningd(8), so *--foo* becomes simply *foo* in the configuration
@@ -103,9 +103,28 @@ Sets the working directory. All files (except *--conf* and
  **pid-file**=*PATH*
 Specify pid file to write to.
 
- **log-level**=*LEVEL*
+ **log-level**=*LEVEL*\[:*SUBSYSTEM*\]
 What log level to print out: options are io, debug, info, unusual,
-broken.
+broken.  If *SUBSYSTEM* is supplied, this sets the logging level
+for any subsystem containing that string.  Subsystems include:
+
+* *lightningd*: The main lightning daemon
+* *database*: The database subsystem
+* *wallet*: The wallet subsystem
+* *gossipd*: The gossip daemon
+* *plugin-manager*: The plugin subsystem
+* *plugin-P*: Each plugin, P = plugin path without directory
+* *hsmd*: The secret-holding daemon
+* *gossipd*: The gossip daemon
+* *connectd*: The network connection daemon
+
+The following subsystems exist for each channel, where N is an incrementing
+internal integer id assigned for the lifetime of the channel:
+* *openingd-chan #N*: Each opening / idling daemon
+* *channeld-chan #N*: Each channel management daemon
+* *closingd-chan #N*: Each closing negotiation daemon
+* *onchaind-chan #N*: Each onchain close handling daemon
+* *json #FD*: Each JSONRPC connection, FD = file descriptor number
 
  **log-prefix**=*PREFIX*
 Prefix for log lines: this can be customized if you want to merge logs
diff --git a/lightningd/lightningd.c b/lightningd/lightningd.c
index e50ce5d0c..e306d7833 100644
--- a/lightningd/lightningd.c
+++ b/lightningd/lightningd.c
@@ -165,7 +165,7 @@ static struct lightningd *new_lightningd(const tal_t *ctx)
 	 * book to hold all the entries (and trims as necessary), and multiple
 	 * log objects which each can write into it, each with a unique
 	 * prefix. */
-	ld->log_book = new_log_book(ld, 100*1024*1024, LOG_INFORM);
+	ld->log_book = new_log_book(ld, 100*1024*1024);
 	/*~ Note the tal context arg (by convention, the first argument to any
 	 * allocation function): ld->log will be implicitly freed when ld
 	 * is. */
diff --git a/lightningd/log.c b/lightningd/log.c
index 501a88200..fd98393c3 100644
--- a/lightningd/log.c
+++ b/lightningd/log.c
@@ -29,13 +29,26 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+/* What logging level to use if they didn't specify */
+#define DEFAULT_LOGLEVEL LOG_INFORM
+
 /* Once we're up and running, this is set up. */
 struct log *crashlog;
 
+struct print_filter {
+	struct list_node list;
+
+	const char *prefix;
+	enum log_level level;
+};
+
 struct log_book {
 	size_t mem_used;
 	size_t max_mem;
-	enum log_level print_level;
+	struct list_head print_filters;
+
+	/* Non-null once it's been initialized */
+	enum log_level *default_print_level;
 	struct timeabs init_time;
 	FILE *outf;
 
@@ -51,6 +64,9 @@ struct log {
 	struct log_book *lr;
 	const struct node_id *default_node_id;
 	const char *prefix;
+
+	/* Non-NULL once it's been initialized */
+	enum log_level *print_level;
 };
 
 static const char *level_prefix(enum log_level level)
@@ -145,8 +161,7 @@ static size_t prune_log(struct log_book *log)
 	return deleted;
 }
 
-struct log_book *new_log_book(struct lightningd *ld, size_t max_mem,
-			      enum log_level printlevel)
+struct log_book *new_log_book(struct lightningd *ld, size_t max_mem)
 {
 	struct log_book *lr = tal_linkable(tal(NULL, struct log_book));
 
@@ -155,7 +170,8 @@ struct log_book *new_log_book(struct lightningd *ld, size_t max_mem,
 	lr->mem_used = 0;
 	lr->max_mem = max_mem;
 	lr->outf = stdout;
-	lr->print_level = printlevel;
+	lr->default_print_level = NULL;
+	list_head_init(&lr->print_filters);
 	lr->init_time = time_now();
 	lr->ld = ld;
 	list_head_init(&lr->log);
@@ -163,6 +179,18 @@ struct log_book *new_log_book(struct lightningd *ld, size_t max_mem,
 	return lr;
 }
 
+static enum log_level filter_level(struct log_book *lr, const char *prefix)
+{
+	struct print_filter *i;
+
+	assert(lr->default_print_level != NULL);
+	list_for_each(&lr->print_filters, i, list) {
+		if (strstr(prefix, i->prefix))
+			return i->level;
+	}
+	return *lr->default_print_level;
+}
+
 /* With different entry points */
 struct log *
 new_log(const tal_t *ctx, struct log_book *record,
@@ -184,14 +212,28 @@ new_log(const tal_t *ctx, struct log_book *record,
 	else
 		log->default_node_id = NULL;
 
+	/* Initialized on first use */
+	log->print_level = NULL;
 	return log;
 }
 
-
 const char *log_prefix(const struct log *log)
 {
 	return log->prefix;
 }
+
+enum log_level log_print_level(struct log *log)
+{
+	if (!log->print_level) {
+		/* Not set globally yet?  Print BROKEN messages only */
+		if (!log->lr->default_print_level)
+			return LOG_BROKEN;
+		log->print_level = tal(log, enum log_level);
+		*log->print_level = filter_level(log->lr, log->prefix);
+	}
+	return *log->print_level;
+}
+
 static void add_entry(struct log *log, struct log_entry *l)
 {
 	log->lr->mem_used += mem_used(l);
@@ -225,10 +267,10 @@ static struct log_entry *new_log_entry(struct log *log, enum log_level level,
 	return l;
 }
 
-static void maybe_print(const struct log *log, const struct log_entry *l,
+static void maybe_print(struct log *log, const struct log_entry *l,
 			size_t offset)
 {
-	if (l->level >= log->lr->print_level)
+	if (l->level >= log_print_level(log))
 		log_to_file(log->prefix, l->level, l->node_id, offset != 0,
 			    &l->time, l->log + offset,
 			    l->io, tal_bytelen(l->io), log->lr->outf);
@@ -272,7 +314,7 @@ void log_io(struct log *log, enum log_level dir,
 	assert(dir == LOG_IO_IN || dir == LOG_IO_OUT);
 
 	/* Print first, in case we need to truncate. */
-	if (l->level >= log->lr->print_level)
+	if (l->level >= log_print_level(log))
 		log_to_file(log->prefix, l->level, l->node_id, false,
 			    &l->time, str,
 			    data, len, log->lr->outf);
@@ -415,7 +457,7 @@ static void log_one_line(unsigned int skipped,
 	data->prefix = "\n";
 }
 
-static struct {
+static const struct level {
 	const char *name;
 	enum log_level level;
 } log_levels[] = {
@@ -426,30 +468,69 @@ static struct {
 	{ "BROKEN", LOG_BROKEN }
 };
 
-static char *arg_log_level(const char *arg, struct log *log)
+static const struct level *str_to_level(const char *str, size_t len)
 {
-	size_t i;
-
-	for (i = 0; i < ARRAY_SIZE(log_levels); i++) {
-		if (strcasecmp(arg, log_levels[i].name) == 0) {
-			log->lr->print_level = log_levels[i].level;
-			return NULL;
-		}
+	for (size_t i = 0; i < ARRAY_SIZE(log_levels); i++) {
+		if (strlen(log_levels[i].name) != len)
+			continue;
+		if (strncasecmp(str, log_levels[i].name, len) != 0)
+			continue;
+		return &log_levels[i];
+	}
+	return NULL;
+}
+
+static const char *level_to_str(enum log_level level)
+{
+	for (size_t i = 0; i < ARRAY_SIZE(log_levels); i++) {
+		if (level == log_levels[i].level)
+			return log_levels[i].name;
+	}
+	return NULL;
+}
+
+char *opt_log_level(const char *arg, struct log *log)
+{
+	const struct level *level;
+	int len;
+
+	len = strcspn(arg, ":");
+	level = str_to_level(arg, len);
+	if (!level)
+		return tal_fmt(NULL, "unknown log level %.*s", len, arg);
+
+	if (arg[len]) {
+		struct print_filter *f = tal(log->lr, struct print_filter);
+		f->prefix = arg + len + 1;
+		f->level = level->level;
+		list_add_tail(&log->lr->print_filters, &f->list);
+	} else {
+		tal_free(log->lr->default_print_level);
+		log->lr->default_print_level = tal(log->lr, enum log_level);
+		*log->lr->default_print_level = level->level;
+	}
+	return NULL;
+}
+
+void json_add_opt_log_levels(struct json_stream *response, struct log *log)
+{
+	struct print_filter *i;
+
+	list_for_each(&log->lr->print_filters, i, list) {
+		json_add_member(response, "log-level", true, "%s:%s",
+				level_to_str(i->level), i->prefix);
 	}
-	return tal_fmt(NULL, "unknown log level");
 }
 
 static void show_log_level(char buf[OPT_SHOW_LEN], const struct log *log)
 {
-	size_t i;
+	enum log_level l;
 
-	for (i = 0; i < ARRAY_SIZE(log_levels); i++) {
-		if (log->lr->print_level == log_levels[i].level) {
-			strncpy(buf, log_levels[i].name, OPT_SHOW_LEN-1);
-			return;
-		}
-	}
-	abort();
+	if (log->lr->default_print_level)
+		l = *log->lr->default_print_level;
+	else
+		l = DEFAULT_LOGLEVEL;
+	strncpy(buf, level_to_str(l), OPT_SHOW_LEN-1);
 }
 
 static char *arg_log_prefix(const char *arg, struct log *log)
@@ -516,7 +597,6 @@ static void setup_log_rotation(struct lightningd *ld)
 
 char *arg_log_to_file(const char *arg, struct lightningd *ld)
 {
-	const struct log_entry *i;
 	int size;
 
 	if (ld->logfile) {
@@ -535,10 +615,6 @@ char *arg_log_to_file(const char *arg, struct lightningd *ld)
 	if (size > 0)
 		fprintf(ld->log->lr->outf, "\n\n\n\n");
 
-	/* Catch up */
-	list_for_each(&ld->log->lr->log, i, list)
-		maybe_print(ld->log, i, 0);
-
 	log_debug(ld->log, "Opened log file %s", arg);
 	return NULL;
 }
@@ -546,8 +622,8 @@ char *arg_log_to_file(const char *arg, struct lightningd *ld)
 void opt_register_logging(struct lightningd *ld)
 {
 	opt_register_early_arg("--log-level",
-			       arg_log_level, show_log_level, ld->log,
-			       "log level (io, debug, info, unusual, broken)");
+			       opt_log_level, show_log_level, ld->log,
+			       "log level (io, debug, info, unusual, broken) [:prefix]");
 	opt_register_early_arg("--log-prefix", arg_log_prefix, show_log_prefix,
 			       ld->log,
 			       "log prefix");
@@ -555,6 +631,25 @@ void opt_register_logging(struct lightningd *ld)
 			       "log to file instead of stdout");
 }
 
+void logging_options_parsed(struct log_book *lr)
+{
+	const struct log_entry *l;
+
+	/* If they didn't set an explicit level, set to info */
+	if (!lr->default_print_level) {
+		lr->default_print_level = tal(lr, enum log_level);
+		*lr->default_print_level = DEFAULT_LOGLEVEL;
+	}
+
+	/* Catch up, since before we were only printing BROKEN msgs */
+	list_for_each(&lr->log, l, list) {
+		if (l->level >= filter_level(lr, l->prefix))
+			log_to_file(l->prefix, l->level, l->node_id, false,
+				    &l->time, l->log,
+				    l->io, tal_bytelen(l->io), lr->outf);
+	}
+}
+
 void log_backtrace_print(const char *fmt, ...)
 {
 	va_list ap;
diff --git a/lightningd/log.h b/lightningd/log.h
index 605c1db69..1c0504cb0 100644
--- a/lightningd/log.h
+++ b/lightningd/log.h
@@ -18,8 +18,7 @@ struct timerel;
 
 /* We can have a single log book, with multiple logs in it: it's freed
  * by the last struct log itself. */
-struct log_book *new_log_book(struct lightningd *ld, size_t max_mem,
-			      enum log_level printlevel);
+struct log_book *new_log_book(struct lightningd *ld, size_t max_mem);
 
 /* With different entry points */
 struct log *new_log(const tal_t *ctx, struct log_book *record,
@@ -52,6 +51,7 @@ void logv(struct log *log, enum log_level level, const struct node_id *node_id,
 void logv_add(struct log *log, const char *fmt, va_list ap);
 
 const char *log_prefix(const struct log *log);
+enum log_level log_print_level(struct log *log);
 
 void opt_register_logging(struct lightningd *ld);
 
@@ -88,4 +88,8 @@ struct log_entry {
 	const u8 *io;
 };
 
+/* For options.c's listconfig */
+char *opt_log_level(const char *arg, struct log *log);
+void json_add_opt_log_levels(struct json_stream *response, struct log *log);
+void logging_options_parsed(struct log_book *lr);
 #endif /* LIGHTNING_LIGHTNINGD_LOG_H */
diff --git a/lightningd/options.c b/lightningd/options.c
index fb85fd407..73a0a8b2d 100644
--- a/lightningd/options.c
+++ b/lightningd/options.c
@@ -1194,6 +1194,9 @@ void handle_early_opts(struct lightningd *ld, int argc, char *argv[])
 
 	/* Now we know what network we're on, initialize defaults. */
 	setup_default_config(ld);
+
+	/* Finalize the logging subsystem now. */
+	logging_options_parsed(ld->log_book);
 }
 
 void handle_opts(struct lightningd *ld, int argc, char *argv[])
@@ -1351,6 +1354,8 @@ static void add_config(struct lightningd *ld,
 				answer = fmt_wireaddr(name0, ld->proxyaddr);
 		} else if (opt->cb_arg == (void *)opt_add_plugin) {
 			json_add_opt_plugins(response, ld->plugins);
+		} else if (opt->cb_arg == (void *)opt_log_level) {
+			json_add_opt_log_levels(response, ld->log);
 		} else if (opt->cb_arg == (void *)opt_add_plugin_dir
 			   || opt->cb_arg == (void *)opt_disable_plugin
 			   || opt->cb_arg == (void *)plugin_opt_set) {
diff --git a/lightningd/test/run-find_my_abspath.c b/lightningd/test/run-find_my_abspath.c
index 210cdbb36..d84d5d144 100644
--- a/lightningd/test/run-find_my_abspath.c
+++ b/lightningd/test/run-find_my_abspath.c
@@ -135,8 +135,7 @@ struct log *new_log(const tal_t *ctx UNNEEDED, struct log_book *record UNNEEDED,
 		    const char *fmt UNNEEDED, ...)
 { fprintf(stderr, "new_log called!\n"); abort(); }
 /* Generated stub for new_log_book */
-struct log_book *new_log_book(struct lightningd *ld UNNEEDED, size_t max_mem UNNEEDED,
-			      enum log_level printlevel UNNEEDED)
+struct log_book *new_log_book(struct lightningd *ld UNNEEDED, size_t max_mem UNNEEDED)
 { fprintf(stderr, "new_log_book called!\n"); abort(); }
 /* Generated stub for new_topology */
 struct chain_topology *new_topology(struct lightningd *ld UNNEEDED, struct log *log UNNEEDED)
diff --git a/lightningd/test/run-invoice-select-inchan.c b/lightningd/test/run-invoice-select-inchan.c
index 16327a9ab..2beecd502 100644
--- a/lightningd/test/run-invoice-select-inchan.c
+++ b/lightningd/test/run-invoice-select-inchan.c
@@ -179,12 +179,6 @@ void json_add_log(struct json_stream *result UNNEEDED,
 		  const struct node_id *node_id UNNEEDED,
 		  enum log_level minlevel UNNEEDED)
 { fprintf(stderr, "json_add_log called!\n"); abort(); }
-/* Generated stub for json_add_member */
-void json_add_member(struct json_stream *js UNNEEDED,
-		     const char *fieldname UNNEEDED,
-		     bool quote UNNEEDED,
-		     const char *fmt UNNEEDED, ...)
-{ fprintf(stderr, "json_add_member called!\n"); abort(); }
 /* Generated stub for json_add_node_id */
 void json_add_node_id(struct json_stream *response UNNEEDED,
 				const char *fieldname UNNEEDED,
diff --git a/wallet/test/run-wallet.c b/wallet/test/run-wallet.c
index 23bb383d3..c3e0ae6ab 100644
--- a/wallet/test/run-wallet.c
+++ b/wallet/test/run-wallet.c
@@ -252,12 +252,6 @@ void json_add_log(struct json_stream *result UNNEEDED,
 		  const struct node_id *node_id UNNEEDED,
 		  enum log_level minlevel UNNEEDED)
 { fprintf(stderr, "json_add_log called!\n"); abort(); }
-/* Generated stub for json_add_member */
-void json_add_member(struct json_stream *js UNNEEDED,
-		     const char *fieldname UNNEEDED,
-		     bool quote UNNEEDED,
-		     const char *fmt UNNEEDED, ...)
-{ fprintf(stderr, "json_add_member called!\n"); abort(); }
 /* Generated stub for json_add_node_id */
 void json_add_node_id(struct json_stream *response UNNEEDED,
 				const char *fieldname UNNEEDED,
@@ -703,8 +697,7 @@ struct log *new_log(const tal_t *ctx UNNEEDED, struct log_book *record UNNEEDED,
 	return NULL;
 }
 
-struct log_book *new_log_book(struct lightningd *ld UNNEEDED, size_t max_mem UNNEEDED,
-			      enum log_level printlevel UNNEEDED)
+struct log_book *new_log_book(struct lightningd *ld UNNEEDED, size_t max_mem UNNEEDED)
 {
 	return NULL;
 }