diff --git a/core/tw-opts.c b/core/tw-opts.c
index cf440d53a..1b2b03641 100644
--- a/core/tw-opts.c
+++ b/core/tw-opts.c
@@ -10,6 +10,12 @@ static int is_empty(const tw_optdef *def);
 static const tw_optdef *opt_groups[10];
 static unsigned int opt_index = 0;
 
+// internally set options registered with tw_opt_set
+#define I_ARGV_MAX 16
+static int    i_argc = 0;
+static char * i_argv[I_ARGV_MAX];
+static int tw_parse_called = 0;
+
 void
 tw_opt_add(const tw_optdef *options)
 {
@@ -121,7 +127,7 @@ show_help(void)
 			cnt++;
 		}
 	}
-        
+
         // CMake used to pass options by command line flags
 	fprintf(stderr, "ROSS CMake Configuration Options:\n");
         fprintf(stderr, "  (See build-dir/core/config.h)\n");
@@ -130,7 +136,7 @@ show_help(void)
 void tw_opt_settings(FILE *outfile) {
     const tw_optdef **group = all_groups;
     unsigned cnt = 0;
-    
+
     for (; *group; group++){
         const tw_optdef *def = *group;
         for (; def->type; def++){
@@ -213,7 +219,7 @@ tw_opt_print(void)
 		const tw_optdef *def = *group;
 		for (; def->type; def++)
 		{
-			if (def->type == TWOPTTYPE_GROUP || 
+			if (def->type == TWOPTTYPE_GROUP ||
 				(def->name && 0 == strcmp(def->name, "help")))
 				continue;
 
@@ -398,6 +404,8 @@ tw_opt_parse(int *argc_p, char ***argv_p)
 	char **argv = *argv_p;
 	unsigned i;
 
+        tw_parse_called = 1;
+
 	program = strrchr(argv[0], '/');
 	if (program)
 		program++;
@@ -415,6 +423,13 @@ tw_opt_parse(int *argc_p, char ***argv_p)
 	all_groups[i++] = basic;
 	all_groups[i] = NULL;
 
+        while (i_argc > 0) {
+            i_argc--;
+            const char *s = i_argv[i_argc];
+            match_opt(s);
+            free(s);
+        }
+
 	while (argc > 1)
 	{
 		const char *s = argv[1];
@@ -436,3 +451,29 @@ tw_opt_parse(int *argc_p, char ***argv_p)
 	*argc_p = argc;
 	*argv_p = argv;
 }
+
+/**
+ * construct internal arguments to look like command line arguments
+ * these cannot be processed until ross is fully set up and tw_opt_parse is called (from tw_init)
+ */
+void tw_opt_set(const char *opt, const char *value) {
+    if (i_argc >= I_ARGV_MAX) {
+        tw_error(TW_LOC, "Too many internal options, increase I_ARGV_MAX.");
+    }
+
+    unsigned long len = strlen(opt) + strlen(value) + 4;
+    char * s = (char *)malloc(len*sizeof(char));
+    strcpy(s, "--");
+    strcat(s, opt);
+    strcat(s, "=");
+    strcat(s, value);
+
+    if (!tw_parse_called) {
+        // save until ROSS has been fully initialized
+        i_argv[i_argc] = s;
+        i_argc++;
+    } else {
+        match_opt(s);
+        free(s);
+    }
+}
diff --git a/core/tw-opts.h b/core/tw-opts.h
index 5337d9c06..c81d0bd34 100644
--- a/core/tw-opts.h
+++ b/core/tw-opts.h
@@ -36,6 +36,8 @@ struct tw_optdef
 extern void tw_opt_parse(int *argc, char ***argv);
 /** Add an opt group */
 extern void tw_opt_add(const tw_optdef *options);
+/** Set an option at runtime. Command line take precedence */
+extern void tw_opt_set(const char *option, const char *value);
 /** Pretty-print the option descriptions (for --help) */
 extern void tw_opt_print(void);
 /** Pretty-print the option descriptions and current values */