diff --git a/src/emu/debug/debugcon.cpp b/src/emu/debug/debugcon.cpp
index e19d23e6b55..0fc33d32f10 100644
--- a/src/emu/debug/debugcon.cpp
+++ b/src/emu/debug/debugcon.cpp
@@ -58,6 +58,9 @@ debugger_console::debugger_console(running_machine &machine)
 	/* listen in on the errorlog */
 	using namespace std::placeholders;
 	m_machine.add_logerror_callback(std::bind(&debugger_console::errorlog_write_line, this, _1));
+
+	/* register our own custom-command help */
+	register_command("helpcustom", CMDFLAG_NONE, 0, 0, 0, std::bind(&debugger_console::execute_help_custom, this, _1, _2));
 }
 
 
@@ -92,6 +95,28 @@ void debugger_console::exit()
 
 ***************************************************************************/
 
+/*------------------------------------------------------------
+    execute_help_custom - execute the helpcustom command
+------------------------------------------------------------*/
+
+void debugger_console::execute_help_custom(int ref, const std::vector<std::string> &params)
+{
+	debug_command *cmd = m_commandlist;
+	char buf[64];
+	while (cmd)
+	{
+		if (cmd->flags & CMDFLAG_CUSTOM_HELP)
+		{
+			snprintf(buf, 63, "%s help", cmd->command);
+			buf[63] = 0;
+			char *temp_params[1] = { buf };
+			internal_execute_command(true, 1, &temp_params[0]);
+		}
+		cmd = cmd->next;
+	}
+}
+
+
 /*-------------------------------------------------
     trim_parameter - executes a
     command
diff --git a/src/emu/debug/debugcon.h b/src/emu/debug/debugcon.h
index a64238ed8c6..289123591f0 100644
--- a/src/emu/debug/debugcon.h
+++ b/src/emu/debug/debugcon.h
@@ -28,6 +28,7 @@
 /* flags for command parsing */
 #define CMDFLAG_NONE                        (0x0000)
 #define CMDFLAG_KEEP_QUOTES                 (0x0001)
+#define CMDFLAG_CUSTOM_HELP                 (0x0002)
 
 /* values for the error code in a command error */
 #define CMDERR_NONE                         (0)
@@ -111,6 +112,8 @@ public:
 private:
 	void exit();
 
+	void execute_help_custom(int ref, const std::vector<std::string> &params);
+
 	void trim_parameter(char **paramptr, bool keep_quotes);
 	CMDERR internal_execute_command(bool execute, int params, char **param);
 	CMDERR internal_parse_command(const std::string &original_command, bool execute);
diff --git a/src/emu/debug/debughlp.cpp b/src/emu/debug/debughlp.cpp
index 5a272c85a1b..d737c0376aa 100644
--- a/src/emu/debug/debughlp.cpp
+++ b/src/emu/debug/debughlp.cpp
@@ -78,6 +78,7 @@ static const help_item static_help_list[] =
 		"Type help <command> for further details on each command\n"
 		"\n"
 		"  help [<topic>] -- get help on a particular topic\n"
+		"  helpcustom -- get help on any custom commands registered by devices\n"
 		"  do <expression> -- evaluates the given expression\n"
 		"  symlist [<CPU>] -- lists registered symbols\n"
 		"  softreset -- executes a soft reset\n"
diff --git a/src/mame/machine/model2.cpp b/src/mame/machine/model2.cpp
index af38c3e7f26..600619d92b8 100644
--- a/src/mame/machine/model2.cpp
+++ b/src/mame/machine/model2.cpp
@@ -21,7 +21,7 @@ void model2_state::debug_init()
 	if (machine().debug_flags & DEBUG_FLAG_ENABLED)
 	{
 		using namespace std::placeholders;
-		machine().debugger().console().register_command("m2", CMDFLAG_NONE, 0, 1, 2, std::bind(&model2_state::debug_commands, this, _1, _2));
+		machine().debugger().console().register_command("m2", CMDFLAG_CUSTOM_HELP, 0, 1, 2, std::bind(&model2_state::debug_commands, this, _1, _2));
 	}
 }
 
diff --git a/src/mame/machine/xbox.cpp b/src/mame/machine/xbox.cpp
index 8deb4ecd352..e31e0a9c479 100644
--- a/src/mame/machine/xbox.cpp
+++ b/src/mame/machine/xbox.cpp
@@ -822,7 +822,7 @@ void xbox_base_state::machine_start()
 	if (machine().debug_flags & DEBUG_FLAG_ENABLED)
 	{
 		using namespace std::placeholders;
-		machine().debugger().console().register_command("xbox", CMDFLAG_NONE, 0, 1, 4, std::bind(&xbox_base_state::xbox_debug_commands, this, _1, _2));
+		machine().debugger().console().register_command("xbox", CMDFLAG_CUSTOM_HELP, 0, 1, 4, std::bind(&xbox_base_state::xbox_debug_commands, this, _1, _2));
 	}
 	subdevice<xbox_eeprom_device>("pci:01.1:154")->hack_eeprom =
 		[&](void)