Index: lib/libc/sys/procctl.2
===================================================================
--- lib/libc/sys/procctl.2
+++ lib/libc/sys/procctl.2
@@ -430,15 +430,20 @@
 .Er ECAPMODE
 error.
 If the control is enabled, such errors from the syscalls cause
-delivery of the synchronous
+delivery of either a synchronous
 .Dv SIGTRAP
+or
+.Dv SIGCAP
 signal to the thread immediately before returning from the syscalls.
+The former is useful for debugging processes that are unexpectedly failing in
+capability mode, the latter is intended to be caught by the process and used to
+handle the failure within the process.
 .Pp
 Possible values for the
 .Fa data
 argument are:
 .Bl -tag -width PROC_TRAPCAP_CTL_DISABLE
-.It Dv PROC_TRAPCAP_CTL_ENABLE
+.It Dv PROC_TRAPCAP_CTL_ENABLE_SIGTRAP
 Enable the
 .Dv SIGTRAP
 signal delivery on capability mode access violations.
@@ -446,6 +451,18 @@
 and is kept after
 .Xr fexecve 2
 calls.
+.It Dv PROC_TRAPCAP_CTL_ENABLE
+is an alias for
+.Dv PROC_TRAPCAP_CTL_ENABLE_SIGTRAP
+for legacy compatibility.
+.It Dv PROC_TRAPCAP_CTL_ENABLE_SIGCAP
+Enable the
+.Dv SIGCAP
+signal delivery on capability mode access violations.
+The enabled mode is inherited by the children of the process,
+and is kept after
+.Xr fexecve 2
+calls.
 .It Dv PROC_TRAPCAP_CTL_DISABLE
 Disable the signal delivery on capability mode access violations.
 Note that the global sysctl
Index: sys/kern/kern_procctl.c
===================================================================
--- sys/kern/kern_procctl.c
+++ sys/kern/kern_procctl.c
@@ -408,12 +408,24 @@
 	PROC_LOCK_ASSERT(p, MA_OWNED);
 	state = *(int *)data;
 
-	switch (state) {
+	/*
+	 * The low two bits of the state indicate whether trapping should be
+	 * enabled or disabled (0b01 enable, 0b10 disable).  In the enable
+	 * commands, bit 2 indicates whether the signal should be SIGTRAP (0) or
+	 * SIGCAP (1).
+	 */
+	switch (state & 3) {
 	case PROC_TRAPCAP_CTL_ENABLE:
 		p->p_flag2 |= P2_TRAPCAP;
+		if (state == PROC_TRAPCAP_CTL_ENABLE_SIGCAP) {
+			p->p_flag2 |= P2_SIGCAP;
+		} else {
+			p->p_flag2 &= ~P2_SIGCAP;
+		}
 		break;
 	case PROC_TRAPCAP_CTL_DISABLE:
 		p->p_flag2 &= ~P2_TRAPCAP;
+		p->p_flag2 &= ~P2_SIGCAP;
 		break;
 	default:
 		return (EINVAL);
@@ -427,8 +439,10 @@
 	int *status;
 
 	status = data;
-	*status = (p->p_flag2 & P2_TRAPCAP) != 0 ? PROC_TRAPCAP_CTL_ENABLE :
-	    PROC_TRAPCAP_CTL_DISABLE;
+	*status = (p->p_flag2 & P2_TRAPCAP) != 0 ?
+		(((p->p_flag2 & P2_SIGCAP) != 0) ?
+		 PROC_TRAPCAP_CTL_ENABLE_SIGCAP : PROC_TRAPCAP_CTL_ENABLE) :
+		PROC_TRAPCAP_CTL_DISABLE;
 	return (0);
 }
 
Index: sys/kern/subr_syscall.c
===================================================================
--- sys/kern/subr_syscall.c
+++ sys/kern/subr_syscall.c
@@ -225,7 +225,8 @@
 		if ((trap_enotcap ||
 		    (p->p_flag2 & P2_TRAPCAP) != 0) && IN_CAPABILITY_MODE(td)) {
 			ksiginfo_init_trap(&ksi);
-			ksi.ksi_signo = SIGTRAP;
+			ksi.ksi_signo =
+			    ((p->p_flag2 & P2_SIGCAP) == 0) ? SIGTRAP : SIGCAP;
 			ksi.ksi_errno = td->td_errno;
 			ksi.ksi_code = TRAP_CAP;
 			ksi.ksi_info.si_syscall = sa->original_code;
Index: sys/sys/proc.h
===================================================================
--- sys/sys/proc.h
+++ sys/sys/proc.h
@@ -841,6 +841,7 @@
 #define	P2_NO_NEW_PRIVS		0x00008000	/* Ignore setuid */
 #define	P2_WXORX_DISABLE	0x00010000	/* WX mappings enabled */
 #define	P2_WXORX_ENABLE_EXEC	0x00020000	/* WXORX enabled after exec */
+#define	P2_SIGCAP		0x00040000	/* SIGCAP on ENOTCAPABLE */
 
 /* Flags protected by proctree_lock, kept in p_treeflags. */
 #define	P_TREE_ORPHANED		0x00000001	/* Reparented, on orphan list */
Index: sys/sys/procctl.h
===================================================================
--- sys/sys/procctl.h
+++ sys/sys/procctl.h
@@ -67,6 +67,8 @@
 #define	PROC_NO_NEW_PRIVS_STATUS 20	/* query suid/sgid disabled status */
 #define	PROC_WXMAP_CTL		21	/* control W^X */
 #define	PROC_WXMAP_STATUS	22	/* query W^X */
+#define	PROC_SIGCAP_CTL		23	/* signal on capability errors */
+#define	PROC_SIGCAP_STATUS	24	/* query signal on capability status */
 
 /* Operations for PROC_SPROTECT (passed in integer arg). */
 #define	PPROT_OP(x)	((x) & 0xf)
@@ -129,6 +131,8 @@
 
 #define	PROC_TRAPCAP_CTL_ENABLE		1
 #define	PROC_TRAPCAP_CTL_DISABLE	2
+#define	PROC_TRAPCAP_CTL_ENABLE_SIGTRAP	PROC_TRAPCAP_CTL_ENABLE
+#define	PROC_TRAPCAP_CTL_ENABLE_SIGCAP	(PROC_TRAPCAP_CTL_ENABLE | 4)
 
 #define	PROC_ASLR_FORCE_ENABLE		1
 #define	PROC_ASLR_FORCE_DISABLE		2
Index: sys/sys/signal.h
===================================================================
--- sys/sys/signal.h
+++ sys/sys/signal.h
@@ -131,6 +131,7 @@
 #define	SIGTHR		32	/* reserved by thread library. */
 #define	SIGLWP		SIGTHR
 #define	SIGLIBRT	33	/* reserved by real-time library. */
+#define	SIGCAP		34	/* Capsicum violation. */
 #endif
 
 #define	SIGRTMIN	65
Index: usr.bin/proccontrol/proccontrol.c
===================================================================
--- usr.bin/proccontrol/proccontrol.c
+++ usr.bin/proccontrol/proccontrol.c
@@ -232,8 +232,11 @@
 			break;
 		case MODE_TRAPCAP:
 			switch (arg) {
-			case PROC_TRAPCAP_CTL_ENABLE:
-				printf("enabled\n");
+			case PROC_TRAPCAP_CTL_ENABLE_SIGTRAP:
+				printf("enabled, delivering SIGTRAP\n");
+				break;
+			case PROC_TRAPCAP_CTL_ENABLE_SIGCAP:
+				printf("enabled, delivering SIGCAP\n");
 				break;
 			case PROC_TRAPCAP_CTL_DISABLE:
 				printf("disabled\n");