Index: sys/mips/include/tls.h
===================================================================
--- sys/mips/include/tls.h
+++ sys/mips/include/tls.h
@@ -44,12 +44,14 @@
 #define TLS_DTP_OFFSET	0x8000
 
 #ifdef __mips_n64
-#define TLS_TCB_SIZE	16
+#define	TLS_TCB_SIZE	16
 #ifdef COMPAT_FREEBSD32
-#define TLS_TCB_SIZE32	8
+#define	TLS_TCB_SIZE32	8
 #endif
 #else
-#define TLS_TCB_SIZE	8
+#define	TLS_TCB_SIZE	8
 #endif
 
+#define	MIPS_TCB_DYNAMIC	0
+
 #endif	/* __MIPS_TLS_H__ */
Index: sys/mips/mips/sys_machdep.c
===================================================================
--- sys/mips/mips/sys_machdep.c
+++ sys/mips/mips/sys_machdep.c
@@ -57,13 +57,41 @@
 int
 sysarch(struct thread *td, struct sysarch_args *uap)
 {
-	int error;
-	void *tlsbase;
+	int		  error;
+	void		 *tlsbase;
+#ifdef MIPS_TCB_DYNAMIC
+	int		  tcbsize;
+	uintptr_t 	**tp;
+	uintptr_t 	 *dtv, tls;
+#endif
 
 	switch (uap->op) {
 	case MIPS_SET_TLS:
 		td->td_md.md_tls = uap->parms;
 
+#ifdef MIPS_TCB_DYNAMIC
+		/*
+		 * Default TCB size is constant TLS_TCB_SIZE, but
+		 * due to alignment TCB may be larger. To identify
+		 * actual size, check first index of dtv array.
+		 */
+		tp = td->td_md.md_tls;
+		dtv = *tp;
+
+#define	MIPS_MAX_TCB_SIZE	0x20
+		tls = dtv[2];
+		if ((tls > (uintptr_t)tp + TLS_TCB_SIZE) &&
+		    ((uintptr_t)tp + MIPS_MAX_TCB_SIZE > tls))
+		{
+			/* At index 0 we found shift of TCB, so let's adjust it */
+			tcbsize = tls - (uintptr_t)tp;
+		} else {
+			tcbsize = TLS_TCB_SIZE;
+		}
+#undef MIPS_MAX_TCB_SIZE
+		td->td_md.md_tls_tcb_offset = tcbsize + TLS_TP_OFFSET;
+#endif /* MIPS_TCB_DYNAMIC */
+
 		/*
 		 * If there is an user local register implementation (ULRI)
 		 * update it as well.  Add the TLS and TCB offsets so the