diff --git a/unix/syscall_solaris.go b/unix/syscall_solaris.go
index f4d2a345..76fe8e77 100644
--- a/unix/syscall_solaris.go
+++ b/unix/syscall_solaris.go
@@ -676,6 +676,7 @@ func Poll(fds []PollFd, timeout int) (n int, err error) {
 //sys	connect(s int, addr unsafe.Pointer, addrlen _Socklen) (err error) = libsocket.__xnet_connect
 //sys	mmap(addr uintptr, length uintptr, prot int, flag int, fd int, pos int64) (ret uintptr, err error)
 //sys	munmap(addr uintptr, length uintptr) (err error)
+//sys	sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) = libsendfile.sendfile
 //sys	sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error) = libsocket.__xnet_sendto
 //sys	socket(domain int, typ int, proto int) (fd int, err error) = libsocket.__xnet_socket
 //sysnb	socketpair(domain int, typ int, proto int, fd *[2]int32) (err error) = libsocket.__xnet_socketpair
diff --git a/unix/syscall_solaris_amd64.go b/unix/syscall_solaris_amd64.go
index 9d4e7a67..91c32ddf 100644
--- a/unix/syscall_solaris_amd64.go
+++ b/unix/syscall_solaris_amd64.go
@@ -21,8 +21,3 @@ func (iov *Iovec) SetLen(length int) {
 func (cmsg *Cmsghdr) SetLen(length int) {
 	cmsg.Len = uint32(length)
 }
-
-func sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
-	// TODO(aram): implement this, see issue 5847.
-	panic("unimplemented")
-}
diff --git a/unix/zsyscall_solaris_amd64.go b/unix/zsyscall_solaris_amd64.go
index 5e88619c..39789630 100644
--- a/unix/zsyscall_solaris_amd64.go
+++ b/unix/zsyscall_solaris_amd64.go
@@ -128,6 +128,7 @@ import (
 //go:cgo_import_dynamic libc___xnet_connect __xnet_connect "libsocket.so"
 //go:cgo_import_dynamic libc_mmap mmap "libc.so"
 //go:cgo_import_dynamic libc_munmap munmap "libc.so"
+//go:cgo_import_dynamic libc_sendfile sendfile "libsendfile.so"
 //go:cgo_import_dynamic libc___xnet_sendto __xnet_sendto "libsocket.so"
 //go:cgo_import_dynamic libc___xnet_socket __xnet_socket "libsocket.so"
 //go:cgo_import_dynamic libc___xnet_socketpair __xnet_socketpair "libsocket.so"
@@ -255,6 +256,7 @@ import (
 //go:linkname proc__xnet_connect libc___xnet_connect
 //go:linkname procmmap libc_mmap
 //go:linkname procmunmap libc_munmap
+//go:linkname procsendfile libc_sendfile
 //go:linkname proc__xnet_sendto libc___xnet_sendto
 //go:linkname proc__xnet_socket libc___xnet_socket
 //go:linkname proc__xnet_socketpair libc___xnet_socketpair
@@ -383,6 +385,7 @@ var (
 	proc__xnet_connect,
 	procmmap,
 	procmunmap,
+	procsendfile,
 	proc__xnet_sendto,
 	proc__xnet_socket,
 	proc__xnet_socketpair,
@@ -1589,6 +1592,15 @@ func munmap(addr uintptr, length uintptr) (err error) {
 	return
 }
 
+func sendfile(outfd int, infd int, offset *int64, count int) (written int, err error) {
+	r0, _, e1 := sysvicall6(uintptr(unsafe.Pointer(&procsendfile)), 4, uintptr(outfd), uintptr(infd), uintptr(unsafe.Pointer(offset)), uintptr(count), 0, 0)
+	written = int(r0)
+	if e1 != 0 {
+		err = e1
+	}
+	return
+}
+
 func sendto(s int, buf []byte, flags int, to unsafe.Pointer, addrlen _Socklen) (err error) {
 	var _p0 *byte
 	if len(buf) > 0 {