diff --git a/sys/rtlimits.h b/sys/rtlimits.h
new file mode 100644
index 0000000..a136aa2
--- /dev/null
+++ b/sys/rtlimits.h
@@ -0,0 +1,39 @@
+#ifndef LPC_RTLIMITS_H_
+#define LPC_RTLIMITS_H_
+
+/* Runtime limit index/tag values */
+
+#define LIMIT_EVAL           (0)
+#define LIMIT_ARRAY          (1)
+#define LIMIT_MAPPING        (2)
+#define LIMIT_MAPPING_KEYS   LIMIT_MAPPING
+#define LIMIT_MAPPING_SIZE   (3)
+#define LIMIT_BYTE           (4)
+#define LIMIT_FILE           (5)
+#define LIMIT_CALLOUTS       (6)
+#define LIMIT_COST           (7)
+#define LIMIT_MEMORY         (8)
+
+#define LIMIT_MAX      (9)  /* Number of recognized limits */
+
+/* Special limit values */
+
+#define LIMIT_UNLIMITED    0   /* No limit */
+#define LIMIT_KEEP       (-1)  /* Keep the old limit setting */
+#define LIMIT_DEFAULT    (-2)  /* Use the default setting */
+
+/* memory limits */
+#define MALLOC_SOFT_LIMIT    1
+#define MALLOC_HARD_LIMIT    2
+
+/* low memory conditions */
+#define NO_MALLOC_LIMIT_EXCEEDED     0
+#define SOFT_MALLOC_LIMIT_EXCEEDED   MALLOC_SOFT_LIMIT
+#define HARD_MALLOC_LIMIT_EXCEEDED   MALLOC_HARD_LIMIT
+
+/* Flags for available reserves */
+#define USER_RESERVE_AVAILABLE     0x1
+#define MASTER_RESERVE_AVAILABLE   0x2
+#define SYSTEM_RESERVE_AVAILABLE   0x4
+
+#endif /* LPC_RTLIMITS_H_ */