diff --git a/ui/input_readline.c b/ui/input_readline.c
index b629ba8..8ccd55d 100644
--- a/ui/input_readline.c
+++ b/ui/input_readline.c
@@ -25,10 +25,306 @@
 #include <readline/history.h>
 
 #include "input_readline.h"
+#include "cmddb.h"
+#include "opdb.h"
+#include "stab.h"
 #include "util.h"
 
 #define HISTORY_FILENAME "~/.mspdebug_history"
 
+struct find_context {
+	const char *search_text;
+	const char *skip_until;
+	const char *result;
+};
+
+static int cmddb_find_command(void *user_data, const struct cmddb_record *r)
+{
+	struct find_context *find_data = user_data;
+
+	if (find_data->skip_until) {
+		if (r->name == find_data->skip_until)
+			find_data->skip_until = NULL;
+	} else if (!find_data->result) {
+		size_t len = strlen(find_data->search_text);
+		if (strncasecmp(r->name, find_data->search_text, len) == 0)
+			find_data->result = r->name;
+	}
+
+	return 0;
+}
+
+static char *command_generator(const char *text, int state)
+{
+	static struct find_context find_data;
+	if (state == 0) {
+		// start a new search
+		find_data.search_text = text;
+		find_data.skip_until = NULL;
+	} else {
+		// continue searching after the last match
+		find_data.skip_until = find_data.result;
+	}
+	find_data.result = NULL;
+
+	cmddb_enum(cmddb_find_command, &find_data);
+	if (find_data.result)
+		return strdup(find_data.result);
+	return NULL;
+}
+
+static int opdb_find_option(void *user_data, const struct opdb_key *key,
+			    const union opdb_value *value)
+{
+	(void)value;
+	struct find_context *find_data = user_data;
+
+	if (find_data->skip_until) {
+		if (key->name == find_data->skip_until)
+			find_data->skip_until = NULL;
+	} else if (!find_data->result) {
+		size_t len = strlen(find_data->search_text);
+		if (strncasecmp(key->name, find_data->search_text, len) == 0)
+			find_data->result = key->name;
+	}
+
+	return 0;
+}
+
+static char *option_generator(const char *text, int state)
+{
+	static struct find_context find_data;
+	if (state == 0) {
+		// start a new search
+		find_data.search_text = text;
+		find_data.skip_until = NULL;
+	} else {
+		// continue searching after the last match
+		find_data.skip_until = find_data.result;
+	}
+	find_data.result = NULL;
+
+	opdb_enum(opdb_find_option, &find_data);
+	if (find_data.result)
+		return strdup(find_data.result);
+	return NULL;
+}
+
+static int stab_find_symbol(void *user_data, const char *name, address_t value)
+{
+	(void)value;
+	struct find_context *find_data = user_data;
+
+	if (find_data->skip_until) {
+		if (strcmp(name, find_data->skip_until) == 0)
+			find_data->skip_until = NULL;
+	} else if (!find_data->result) {
+		size_t len = strlen(find_data->search_text);
+		if (strncmp(name, find_data->search_text, len) == 0) {
+			// name is stack-allocated and becomes invalid after
+			// returning, so we copy it to a static buffer.
+			static char buffer[MAX_SYMBOL_LENGTH];
+			snprintf(buffer, sizeof(buffer), "%s", name);
+			find_data->result = buffer;
+		}
+	}
+
+	return 0;
+}
+
+static char *symbol_generator(const char *text, int state)
+{
+	static struct find_context find_data;
+	if (state == 0) {
+		// start a new search
+		find_data.search_text = text;
+		find_data.skip_until = NULL;
+	} else {
+		// continue searching after the last match
+		find_data.skip_until = find_data.result;
+	}
+	find_data.result = NULL;
+
+	stab_enum(stab_find_symbol, &find_data);
+	if (find_data.result)
+		return strdup(find_data.result);
+	return NULL;
+}
+
+static char *array_generator(const char *text, int state, const char **array)
+{
+	static const char **array_ptr;
+	if (state == 0) {
+		array_ptr = array;
+	} else {
+		++array_ptr;
+	}
+
+	while (*array_ptr) {
+		if (strncasecmp(*array_ptr, text, strlen(text)) == 0)
+			return strdup(*array_ptr);
+		array_ptr++;
+	}
+	return NULL;
+}
+
+static rl_compentry_func_t *complete_addrcmd(char **arg, const char *line, int start)
+{
+	const char *token = get_arg(arg);
+	if (token == NULL || token == line + start)
+		return symbol_generator;
+	return NULL;
+}
+
+static char *erase_subcmd_generator(const char *text, int state)
+{
+	const char *subcmds[] = { "all", "segment", "segrange", NULL };
+	return array_generator(text, state, subcmds);
+}
+
+static rl_compentry_func_t *complete_erase(char **arg, const char *line, int start)
+{
+	const char *subcmd = get_arg(arg);
+	if (subcmd == NULL || subcmd == line + start)
+		return erase_subcmd_generator;
+	else
+		return complete_addrcmd(arg, line, start);
+}
+
+static rl_compentry_func_t *complete_help(char **arg, const char *line, int start)
+{
+	const char *topic = get_arg(arg);
+	if (topic == NULL || topic == line + start)
+		return command_generator;
+	return NULL;
+}
+
+static rl_compentry_func_t *complete_loadraw(char **arg, const char *line, int start)
+{
+	const char *filename_arg = get_arg(arg);
+	if (filename_arg == NULL || filename_arg == line + start)
+		return NULL; // default filename completion
+	else
+		return complete_addrcmd(arg, line, start);
+}
+
+static rl_compentry_func_t *complete_opt(char **arg, const char *line, int start)
+{
+	const char *opt_text = get_arg(arg);
+	if (opt_text == NULL || opt_text == line + start)
+		return option_generator;
+	return NULL;
+}
+
+static char *power_subcmd_generator(const char *text, int state)
+{
+	const char *subcmds[] = { "info", "clear", "all", "session",
+				  "export-csv", "profile", NULL };
+	return array_generator(text, state, subcmds);
+}
+
+static rl_compentry_func_t *complete_power(char **arg, const char *line, int start)
+{
+	const char *subcmd = get_arg(arg);
+	if (subcmd == NULL || subcmd == line + start)
+		return power_subcmd_generator;
+	return NULL;
+}
+
+static char *simio_subcmd_generator(const char *text, int state)
+{
+	const char *subcmds[] = { "add", "del", "devices", "classes", "help",
+				  "config", "info", NULL };
+	return array_generator(text, state, subcmds);
+}
+
+static rl_compentry_func_t *complete_simio(char **arg, const char *line, int start)
+{
+	const char *subcmd = get_arg(arg);
+	if (subcmd == NULL || subcmd == line + start)
+		return simio_subcmd_generator;
+	return NULL;
+}
+
+static char *sym_subcmd_generator(const char *text, int state)
+{
+	const char *subcmds[] = { "clear", "set", "del", "import", "import+",
+				  "export", "find", "rename", NULL };
+	return array_generator(text, state, subcmds);
+}
+
+static rl_compentry_func_t *complete_sym(char **arg, const char *line, int start)
+{
+	const char *subcmd = get_arg(arg);
+	if (subcmd == NULL || subcmd == line + start)
+		return sym_subcmd_generator;
+	else if (strcasecmp(subcmd, "set") == 0 ||
+		 strcasecmp(subcmd, "del") == 0 ||
+		 strcasecmp(subcmd, "find") == 0)
+		return complete_addrcmd(arg, line, start);
+	return NULL;
+}
+
+struct cmd_completer {
+	const char *name;
+	rl_compentry_func_t *(*completer)(char **arg, const char *line, int start);
+};
+
+static const struct cmd_completer cmd_completers[] = {
+	{ "cgraph",     complete_addrcmd },
+	{ "dis",        complete_addrcmd },
+	{ "erase",	complete_erase },
+	{ "fill",       complete_addrcmd },
+	{ "help",       complete_help },
+	{ "hexout",     complete_addrcmd },
+	{ "isearch",    complete_addrcmd },
+	{ "load_raw",   complete_loadraw },
+	{ "md",         complete_addrcmd },
+	{ "mw",         complete_addrcmd },
+	{ "opt",        complete_opt },
+	{ "power",      complete_power },
+	{ "save_raw",   complete_addrcmd },
+	{ "setbreak",   complete_addrcmd },
+	{ "setwatch",   complete_addrcmd },
+	{ "setwatch_r", complete_addrcmd },
+	{ "setwatch_w", complete_addrcmd },
+	{ "simio",      complete_simio },
+	{ "sym",        complete_sym },
+	{ "verify_raw", complete_loadraw },
+	{ NULL,         NULL }
+};
+
+static char **mspdebug_completion(const char *text, int start, int end)
+{
+	rl_compentry_func_t *generator = NULL;
+
+	// copy the current command line, terminate at cursor position
+	char *line = strdup(rl_line_buffer);
+	line[end] = '\0';
+
+	char *arg = line;
+	const char *cmd_text = get_arg(&arg);
+	struct cmddb_record cmd;
+
+	if (cmd_text == NULL || cmd_text == line + start)
+		generator = command_generator;
+	else if (!cmddb_get(cmd_text, &cmd)) {
+		const struct cmd_completer *c = cmd_completers;
+		while (c->name) {
+			if (!strcmp(cmd.name, c->name)) {
+				generator = c->completer(&arg, line, start);
+				break;
+			}
+			c++;
+		}
+	}
+
+	free(line);
+	if (generator)
+		return rl_completion_matches(text, generator);
+	return NULL;
+}
+
 static int readline_init(void)
 {
 	char *path = expand_tilde(HISTORY_FILENAME);
@@ -36,6 +332,9 @@ static int readline_init(void)
 		read_history(path);
 		free(path);
 	}
+
+	rl_attempted_completion_function = mspdebug_completion;
+
 	return 0;
 }