diff --git a/src/unix/bsd/apple/mod.rs b/src/unix/bsd/apple/mod.rs
index 0eaaced03ec2a..a4b6c9b4e86f2 100644
--- a/src/unix/bsd/apple/mod.rs
+++ b/src/unix/bsd/apple/mod.rs
@@ -21,6 +21,7 @@ pub type tcflag_t = ::c_ulong;
 pub type nl_item = ::c_int;
 pub type id_t = ::c_uint;
 pub type sem_t = ::c_int;
+pub type idtype_t = ::c_uint;
 
 pub enum timezone {}
 
@@ -1363,6 +1364,15 @@ pub const LIO_READ: ::c_int = 1;
 pub const LIO_WAIT: ::c_int = 2;
 pub const LIO_NOWAIT: ::c_int = 1;
 
+pub const WEXITED: ::c_int = 0x00000004;
+pub const WSTOPPED: ::c_int = 0x00000008;
+pub const WCONTINUED: ::c_int = 0x00000010;
+pub const WNOWAIT: ::c_int = 0x00000020;
+
+pub const P_ALL: idtype_t = 0;
+pub const P_PID: idtype_t = 1;
+pub const P_PGID: idtype_t = 2;
+
 f! {
     pub fn WSTOPSIG(status: ::c_int) -> ::c_int {
         status >> 8
@@ -1532,6 +1542,12 @@ extern {
                    flags: ::c_int) -> ::c_int;
 
     pub fn initgroups(user: *const ::c_char, basegroup: ::c_int) -> ::c_int;
+
+    #[cfg_attr(all(target_os = "macos", target_arch = "x86"),
+               link_name = "waitid$UNIX2003")]
+    pub fn waitid(idtype: idtype_t, id: id_t, infop: *mut ::siginfo_t,
+                  options: ::c_int) -> ::c_int;
+
 }
 
 cfg_if! {
diff --git a/src/unix/bsd/freebsdlike/freebsd/mod.rs b/src/unix/bsd/freebsdlike/freebsd/mod.rs
index ba56d1e13e781..4d5a4cfa0d676 100644
--- a/src/unix/bsd/freebsdlike/freebsd/mod.rs
+++ b/src/unix/bsd/freebsdlike/freebsd/mod.rs
@@ -9,6 +9,7 @@ pub type sem_t = _sem;
 
 pub type fsblkcnt_t = ::uint64_t;
 pub type fsfilcnt_t = ::uint64_t;
+pub type idtype_t = ::c_uint;
 
 s! {
     pub struct utmpx {
@@ -356,6 +357,18 @@ pub const LC_ALL_MASK: ::c_int = LC_COLLATE_MASK
                                | LC_NUMERIC_MASK
                                | LC_TIME_MASK;
 
+pub const WSTOPPED: ::c_int = 2; // same as WUNTRACED
+pub const WCONTINUED: ::c_int = 4;
+pub const WNOWAIT: ::c_int = 8;
+pub const WEXITED: ::c_int = 16;
+pub const WTRAPPED: ::c_int = 32;
+
+// FreeBSD defines a great many more of these, we only expose the
+// standardized ones.
+pub const P_PID: idtype_t = 0;
+pub const P_PGID: idtype_t = 2;
+pub const P_ALL: idtype_t = 7;
+
 extern {
     pub fn __error() -> *mut ::c_int;
 
@@ -382,6 +395,8 @@ extern {
                             timeout: *mut ::timespec) -> ::ssize_t;
 
     pub fn freelocale(loc: ::locale_t) -> ::c_int;
+    pub fn waitid(idtype: idtype_t, id: ::id_t, infop: *mut ::siginfo_t,
+                  options: ::c_int) -> ::c_int;
 }
 
 cfg_if! {
diff --git a/src/unix/bsd/netbsdlike/netbsd/mod.rs b/src/unix/bsd/netbsdlike/netbsd/mod.rs
index 57a34130c919c..2f85513408b2f 100644
--- a/src/unix/bsd/netbsdlike/netbsd/mod.rs
+++ b/src/unix/bsd/netbsdlike/netbsd/mod.rs
@@ -4,6 +4,7 @@ pub type dev_t = u64;
 pub type blksize_t = ::int32_t;
 pub type fsblkcnt_t = ::uint64_t;
 pub type fsfilcnt_t = ::uint64_t;
+pub type idtype_t = ::c_int;
 
 s! {
     pub struct aiocb {
@@ -583,6 +584,15 @@ pub const SIGEV_NONE: ::c_int = 0;
 pub const SIGEV_SIGNAL: ::c_int = 1;
 pub const SIGEV_THREAD: ::c_int = 2;
 
+pub const WSTOPPED: ::c_int = 0x00000002; // same as WUNTRACED
+pub const WCONTINUED: ::c_int = 0x00000010;
+pub const WEXITED: ::c_int = 0x000000020;
+pub const WNOWAIT: ::c_int = 0x00010000;
+
+pub const P_ALL: idtype_t = 0;
+pub const P_PID: idtype_t = 1;
+pub const P_PGID: idtype_t = 4;
+
 extern {
     pub fn aio_read(aiocbp: *mut aiocb) -> ::c_int;
     pub fn aio_write(aiocbp: *mut aiocb) -> ::c_int;
diff --git a/src/unix/haiku/mod.rs b/src/unix/haiku/mod.rs
index ab53e6c788c68..86e590912857d 100644
--- a/src/unix/haiku/mod.rs
+++ b/src/unix/haiku/mod.rs
@@ -28,6 +28,8 @@ pub type fsblkcnt_t = i64;
 pub type fsfilcnt_t = i64;
 pub type pthread_attr_t = *mut ::c_void;
 pub type nl_item = ::c_int;
+pub type id_t = i32;
+pub type idtype_t = ::c_uint;
 
 pub enum timezone {}
 
@@ -670,6 +672,17 @@ pub const SO_PEERCRED: ::c_int = 0x4000000b;
 
 pub const NI_MAXHOST: ::size_t = 1025;
 
+pub const WNOHANG: ::c_int = 0x01;
+pub const WUNTRACED: ::c_int = 0x02;
+pub const WCONTINUED: ::c_int = 0x04;
+pub const WEXITED: ::c_int = 0x08;
+pub const WSTOPPED: ::c_int = 0x10;
+pub const WNOWAIT: ::c_int = 0x20;
+
+pub const P_ALL: idtype_t = 0;
+pub const P_PID: idtype_t = 1;
+pub const P_PGID: idtype_t = 2;
+
 f! {
     pub fn FD_CLR(fd: ::c_int, set: *mut fd_set) -> () {
         let fd = fd as usize;
@@ -742,6 +755,8 @@ extern {
                        flags: ::c_int) -> ::c_int;
     pub fn pthread_mutex_timedlock(lock: *mut pthread_mutex_t,
                                    abstime: *const ::timespec) -> ::c_int;
+    pub fn waitid(idtype: idtype_t, id: id_t, infop: *mut ::siginfo_t,
+                  options: ::c_int) -> ::c_int;
 }
 
 cfg_if! {
diff --git a/src/unix/notbsd/android/mod.rs b/src/unix/notbsd/android/mod.rs
index 8a1b565d620fe..4b4e26222ad62 100644
--- a/src/unix/notbsd/android/mod.rs
+++ b/src/unix/notbsd/android/mod.rs
@@ -25,6 +25,7 @@ pub type rlim_t = ::c_ulong;
 pub type dev_t = ::c_ulong;
 pub type ino_t = ::c_ulong;
 pub type __CPU_BITTYPE = ::c_ulong;
+pub type idtype_t = ::c_int;
 
 s! {
     pub struct dirent {
diff --git a/src/unix/notbsd/linux/mod.rs b/src/unix/notbsd/linux/mod.rs
index f822a2faa2cfe..13b61df2cde06 100644
--- a/src/unix/notbsd/linux/mod.rs
+++ b/src/unix/notbsd/linux/mod.rs
@@ -17,6 +17,7 @@ pub type msgqnum_t = ::c_ulong;
 pub type msglen_t = ::c_ulong;
 pub type nfds_t = ::c_ulong;
 pub type nl_item = ::c_int;
+pub type idtype_t = ::c_uint;
 
 pub enum fpos64_t {} // TODO: fill this out with a struct
 
diff --git a/src/unix/notbsd/mod.rs b/src/unix/notbsd/mod.rs
index 39ad6d79c0d76..0233d266e917e 100644
--- a/src/unix/notbsd/mod.rs
+++ b/src/unix/notbsd/mod.rs
@@ -624,6 +624,10 @@ pub const SIGEV_SIGNAL: ::c_int = 0;
 pub const SIGEV_NONE: ::c_int = 1;
 pub const SIGEV_THREAD: ::c_int = 2;
 
+pub const P_ALL: idtype_t = 0;
+pub const P_PID: idtype_t = 1;
+pub const P_PGID: idtype_t = 2;
+
 f! {
     pub fn FD_CLR(fd: ::c_int, set: *mut fd_set) -> () {
         let fd = fd as usize;
@@ -851,6 +855,8 @@ extern {
                      buf: *mut ::c_char,
                      buflen: ::size_t) -> ::c_int;
     pub fn clearenv() -> ::c_int;
+    pub fn waitid(idtype: idtype_t, id: id_t, infop: *mut ::siginfo_t,
+                  options: ::c_int) -> ::c_int;
 }
 
 cfg_if! {
diff --git a/src/unix/solaris/mod.rs b/src/unix/solaris/mod.rs
index 3810fc57f2132..b604208583a40 100644
--- a/src/unix/solaris/mod.rs
+++ b/src/unix/solaris/mod.rs
@@ -32,6 +32,8 @@ pub type pthread_key_t = ::c_uint;
 pub type blksize_t = u32;
 pub type fflags_t = u32;
 pub type nl_item = ::c_int;
+pub type id_t = ::c_int;
+pub type idtype_t = ::c_uint;
 
 pub enum timezone {}
 
@@ -550,6 +552,18 @@ pub const SIGXFSZ: ::c_int = 31;
 pub const WNOHANG: ::c_int = 0x40;
 pub const WUNTRACED: ::c_int = 0x04;
 
+pub const WEXITED: ::c_int = 0x01;
+pub const WTRAPPED: ::c_int = 0x02;
+pub const WSTOPPED: ::c_int = WUNTRACED;
+pub const WCONTINUED: ::c_int = 0x08;
+pub const WNOWAIT: ::c_int = 0x80;
+
+// Solaris defines a great many more of these; we only expose the
+// standardized ones.
+pub const P_PID: idtype_t = 0;
+pub const P_PGID: idtype_t = 2;
+pub const P_ALL: idtype_t = 7;
+
 pub const PROT_NONE: ::c_int = 0;
 pub const PROT_READ: ::c_int = 1;
 pub const PROT_WRITE: ::c_int = 2;
@@ -1056,4 +1070,6 @@ extern {
                          abstime: *const ::timespec) -> ::c_int;
     pub fn pthread_mutex_timedlock(lock: *mut pthread_mutex_t,
                                    abstime: *const ::timespec) -> ::c_int;
+    pub fn waitid(idtype: idtype_t, id: id_t, infop: *mut ::siginfo_t,
+                  options: ::c_int) -> ::c_int;
 }