diff --git a/src/internal/poll/hook_cloexec.go b/src/internal/poll/hook_cloexec.go
index 5c93bdaf6c..5fd5449bb0 100644
--- a/src/internal/poll/hook_cloexec.go
+++ b/src/internal/poll/hook_cloexec.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build dragonfly freebsd linux netbsd openbsd
+// +build dragonfly freebsd illumos linux netbsd openbsd
 
 package poll
 
diff --git a/src/internal/poll/sock_cloexec.go b/src/internal/poll/sock_cloexec.go
index 691cb8e36f..ff7982ca9e 100644
--- a/src/internal/poll/sock_cloexec.go
+++ b/src/internal/poll/sock_cloexec.go
@@ -5,7 +5,7 @@
 // This file implements sysSocket and accept for platforms that
 // provide a fast path for setting SetNonblock and CloseOnExec.
 
-// +build dragonfly freebsd linux netbsd openbsd
+// +build dragonfly freebsd illumos linux netbsd openbsd
 
 package poll
 
diff --git a/src/internal/poll/sys_cloexec.go b/src/internal/poll/sys_cloexec.go
index 7b87f136df..4b3c642173 100644
--- a/src/internal/poll/sys_cloexec.go
+++ b/src/internal/poll/sys_cloexec.go
@@ -5,7 +5,7 @@
 // This file implements sysSocket and accept for platforms that do not
 // provide a fast path for setting SetNonblock and CloseOnExec.
 
-// +build aix darwin js,wasm solaris
+// +build aix darwin js,wasm solaris,!illumos
 
 package poll
 
diff --git a/src/net/internal/socktest/sys_cloexec.go b/src/net/internal/socktest/sys_cloexec.go
index 986d89471b..421352c7b4 100644
--- a/src/net/internal/socktest/sys_cloexec.go
+++ b/src/net/internal/socktest/sys_cloexec.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build dragonfly freebsd linux netbsd openbsd
+// +build dragonfly freebsd illumos linux netbsd openbsd
 
 package socktest
 
diff --git a/src/net/main_cloexec_test.go b/src/net/main_cloexec_test.go
index 5398f9eae1..46b9ba5008 100644
--- a/src/net/main_cloexec_test.go
+++ b/src/net/main_cloexec_test.go
@@ -2,7 +2,7 @@
 // Use of this source code is governed by a BSD-style
 // license that can be found in the LICENSE file.
 
-// +build dragonfly freebsd linux netbsd openbsd
+// +build dragonfly freebsd illumos linux netbsd openbsd
 
 package net
 
diff --git a/src/net/sock_cloexec.go b/src/net/sock_cloexec.go
index 0c883dc338..5f345f0f4a 100644
--- a/src/net/sock_cloexec.go
+++ b/src/net/sock_cloexec.go
@@ -5,7 +5,7 @@
 // This file implements sysSocket and accept for platforms that
 // provide a fast path for setting SetNonblock and CloseOnExec.
 
-// +build dragonfly freebsd linux netbsd openbsd
+// +build dragonfly freebsd illumos linux netbsd openbsd
 
 package net
 
diff --git a/src/net/sys_cloexec.go b/src/net/sys_cloexec.go
index 89aad7066a..967b8bea9d 100644
--- a/src/net/sys_cloexec.go
+++ b/src/net/sys_cloexec.go
@@ -5,7 +5,7 @@
 // This file implements sysSocket and accept for platforms that do not
 // provide a fast path for setting SetNonblock and CloseOnExec.
 
-// +build aix darwin solaris
+// +build aix darwin solaris,!illumos
 
 package net
 
diff --git a/src/runtime/cgo/cgo.go b/src/runtime/cgo/cgo.go
index c02b837978..4d2caf6c4f 100644
--- a/src/runtime/cgo/cgo.go
+++ b/src/runtime/cgo/cgo.go
@@ -21,6 +21,7 @@ package cgo
 #cgo openbsd LDFLAGS: -lpthread
 #cgo aix LDFLAGS: -Wl,-berok
 #cgo solaris LDFLAGS: -lxnet
+#cgo illumos LDFLAGS: -lsocket
 
 // Issue 35247.
 #cgo darwin CFLAGS: -Wno-nullability-completeness
diff --git a/src/syscall/syscall_illumos.go b/src/syscall/syscall_illumos.go
index 1484337e1b..d70a436d13 100644
--- a/src/syscall/syscall_illumos.go
+++ b/src/syscall/syscall_illumos.go
@@ -10,11 +10,34 @@ package syscall
 
 import "unsafe"
 
+//go:cgo_import_dynamic libc_accept4 accept4 "libsocket.so"
 //go:cgo_import_dynamic libc_flock flock "libc.so"
 
+//go:linkname procAccept4 libc_accept4
 //go:linkname procFlock libc_flock
 
-var procFlock libcFunc
+var (
+	procAccept4,
+	procFlock libcFunc
+)
+
+func Accept4(fd int, flags int) (int, Sockaddr, error) {
+	var rsa RawSockaddrAny
+	var addrlen _Socklen = SizeofSockaddrAny
+	nfd, _, errno := sysvicall6(uintptr(unsafe.Pointer(&procAccept4)), 4, uintptr(fd), uintptr(unsafe.Pointer(&rsa)), uintptr(unsafe.Pointer(&addrlen)), uintptr(flags), 0, 0)
+	if errno != 0 {
+		return 0, nil, errno
+	}
+	if addrlen > SizeofSockaddrAny {
+		panic("RawSockaddrAny too small")
+	}
+	sa, err := anyToSockaddr(&rsa)
+	if err != nil {
+		Close(int(nfd))
+		return 0, nil, err
+	}
+	return int(nfd), sa, nil
+}
 
 func Flock(fd int, how int) error {
 	_, _, errno := sysvicall6(uintptr(unsafe.Pointer(&procFlock)), 2, uintptr(fd), uintptr(how), 0, 0, 0, 0)