diff --git a/private/private.h b/private/private.h
index b0ee07022..8b1e19670 100644
--- a/private/private.h
+++ b/private/private.h
@@ -189,9 +189,9 @@ void _dispatch_prohibit_transition_to_multithreaded(bool prohibit);
 
 #if TARGET_OS_MAC
 typedef mach_port_t dispatch_runloop_handle_t;
-#elif defined(__linux__) || defined(__FreeBSD__)
+#elif defined(__linux__)
 typedef int dispatch_runloop_handle_t;
-#elif defined(__unix__) && !defined(__linux__) && !defined(__FreeBSD__)
+#elif defined(__unix__)
 typedef uint64_t dispatch_runloop_handle_t;
 #elif defined(_WIN32)
 typedef void *dispatch_runloop_handle_t;
diff --git a/src/event/workqueue.c b/src/event/workqueue.c
index 6bc65c3b6..07cc17bc5 100644
--- a/src/event/workqueue.c
+++ b/src/event/workqueue.c
@@ -293,6 +293,52 @@ _dispatch_workq_count_runnable_workers(dispatch_workq_monitor_t mon)
 
 	_dispatch_unfair_lock_unlock(&mon->registered_tid_lock);
 }
+#elif defined(__FreeBSD__)
+#include <sys/sysctl.h>
+#include <sys/proc.h>
+#include <sys/user.h>
+
+static void
+_dispatch_workq_count_runnable_workers(dispatch_workq_monitor_t mon)
+{
+	struct kinfo_proc kp[WORKQ_MAX_TRACKED_TIDS];
+	size_t size;
+	int count, runners = 0;
+	int mib[] = {CTL_KERN, KERN_PROC, KERN_PROC_PID | KERN_PROC_INC_THREAD, (int)getpid()};
+
+	// get size we need
+	if (sysctl(mib, 4, NULL, &size, NULL, 0) < 0) {
+		_dispatch_debug("workq: failed to get size for kinfo_proc[] from sysctll");
+		return;
+	}
+
+	// only care about up to WORKQ_MAX_TRACKED_TIDS threads
+	size = MIN(sizeof(kp), size);
+
+	if (sysctl(mib, 4, kp, &size, NULL, 0) < 0) {
+		_dispatch_debug("workq: failed to get kinfo_proc[] from sysctl");
+		return;
+	}
+
+	count = (int)(size / sizeof(struct kinfo_proc));
+
+	_dispatch_unfair_lock_lock(&mon->registered_tid_lock);
+
+	for (int i = 0; i < mon->num_registered_tids; ++i) {
+		dispatch_tid tid = mon->registered_tids[i];
+		for (int j = 0; i < count; ++i) {
+			if ((dispatch_tid)kp[j].ki_tid != tid) { continue; }
+			if (kp[j].ki_stat == SRUN || kp[j].ki_stat == SIDL) {
+				++runners;
+				break;
+			}
+		}
+	}
+
+	mon->num_runnable = runners;
+
+	_dispatch_unfair_lock_unlock(&mon->registered_tid_lock);
+}
 #else
 #error must define _dispatch_workq_count_runnable_workers
 #endif
diff --git a/src/event/workqueue_internal.h b/src/event/workqueue_internal.h
index 118d42db5..cc9474e80 100644
--- a/src/event/workqueue_internal.h
+++ b/src/event/workqueue_internal.h
@@ -30,7 +30,7 @@
 void _dispatch_workq_worker_register(dispatch_queue_global_t root_q);
 void _dispatch_workq_worker_unregister(dispatch_queue_global_t root_q);
 
-#if defined(__linux__) || defined(_WIN32) || defined(__OpenBSD__)
+#if defined(__linux__) || defined(_WIN32) || defined(__OpenBSD__) || defined(__FreeBSD__)
 #define HAVE_DISPATCH_WORKQ_MONITORING 1
 #else
 #define HAVE_DISPATCH_WORKQ_MONITORING 0
diff --git a/src/init.c b/src/init.c
index 1640cbab8..2f2efb0ae 100644
--- a/src/init.c
+++ b/src/init.c
@@ -1049,7 +1049,11 @@ _dispatch_bug_kevent_vanished(dispatch_unote_t du)
 			"{ %p[%s], ident: %" PRIdPTR " / 0x%" PRIxPTR ", handler: %p }",
 			dux_type(du._du)->dst_kind, dou._dq,
 			dou._dq->dq_label ? dou._dq->dq_label : "<unknown>",
+#if defined(__FreeBSD__)
+			(intptr_t)du._du->du_ident, (intptr_t)du._du->du_ident, func);
+#else
 			(intptr_t)du._du->du_ident, (uintptr_t)du._du->du_ident, func);
+#endif
 }
 
 #endif // RDAR_49023449
diff --git a/src/internal.h b/src/internal.h
index 9f74f2c19..a67a771dc 100644
--- a/src/internal.h
+++ b/src/internal.h
@@ -277,6 +277,9 @@ upcast(dispatch_object_t dou)
 #include <sys/sysctl.h>
 #include <sys/queue.h>
 #endif
+#if defined(__FreeBSD__)
+#include <sys/eventfd.h>
+#endif // __FreeBSD__
 #include <sys/socket.h>
 #include <sys/time.h>
 #include <sys/mman.h>
diff --git a/src/io.c b/src/io.c
index 8b03e2934..95c9d2d60 100644
--- a/src/io.c
+++ b/src/io.c
@@ -22,7 +22,6 @@
 
 #if defined(__FreeBSD__)
 #include <fcntl.h>
-#define F_RDADVISE F_RDAHEAD
 #endif
 
 #ifndef DISPATCH_IO_DEBUG
diff --git a/src/queue.c b/src/queue.c
index 356fef19b..1d948e947 100644
--- a/src/queue.c
+++ b/src/queue.c
@@ -6490,7 +6490,7 @@ _dispatch_runloop_queue_get_handle(dispatch_lane_t dq)
 #elif defined(__linux__)
 	// decode: 0 is a valid fd, so offset by 1 to distinguish from NULL
 	return ((dispatch_runloop_handle_t)(uintptr_t)dq->do_ctxt) - 1;
-#elif defined(__unix__) && !defined(__linux__)
+#elif defined(__unix__)
 	return ((dispatch_runloop_handle_t)(uintptr_t)dq->do_ctxt);
 #elif defined(_WIN32)
 	return ((dispatch_runloop_handle_t)(uintptr_t)dq->do_ctxt);
@@ -6509,7 +6509,7 @@ _dispatch_runloop_queue_set_handle(dispatch_lane_t dq,
 #elif defined(__linux__)
 	// encode: 0 is a valid fd, so offset by 1 to distinguish from NULL
 	dq->do_ctxt = (void *)(uintptr_t)(handle + 1);
-#elif defined(__unix__) && !defined(__linux__)
+#elif defined(__unix__)
 	dq->do_ctxt = (void *)(uintptr_t)handle;
 #elif defined(_WIN32)
 	dq->do_ctxt = (void *)(uintptr_t)handle;
@@ -6574,6 +6574,7 @@ _dispatch_runloop_queue_handle_init(void *ctxt)
 	}
 	handle = fd;
 #elif defined(__unix__) && !defined(__linux__)
+	// swift-corelib-foundation PR #3004 implemented a pipe based queue handle
 	int fds[2];
 	int r = pipe2(fds, O_CLOEXEC | O_NONBLOCK);
 	if (r == -1) {
diff --git a/src/shims/lock.c b/src/shims/lock.c
index 8102c877c..6d0ab8764 100644
--- a/src/shims/lock.c
+++ b/src/shims/lock.c
@@ -54,9 +54,20 @@ _dispatch_thread_switch(dispatch_lock value, dispatch_lock_options_t flags,
 	SwitchToThread();
 }
 #endif
-#endif
-
-#if defined(__unix__)
+#elif defined(__FreeBSD__)
+#if !HAVE_UL_UNFAIR_LOCK
+DISPATCH_ALWAYS_INLINE
+static inline void
+_dispatch_thread_switch(dispatch_lock value, dispatch_lock_options_t flags,
+		uint32_t timeout)
+{
+  (void)value;
+  (void)flags;
+  (void)timeout;
+  sched_yield();
+}
+#endif // HAVE_UL_UNFAIR_LOCK
+#elif defined(__unix__)
 #if !HAVE_UL_UNFAIR_LOCK && !HAVE_FUTEX_PI
 DISPATCH_ALWAYS_INLINE
 static inline void
@@ -539,6 +550,16 @@ _dispatch_wait_on_address(uint32_t volatile *_address, uint32_t value,
 			? INFINITE : ((nsecs + 1000000) / 1000000);
 	if (dwMilliseconds == 0) return ETIMEDOUT;
 	return WaitOnAddress(address, &value, sizeof(value), dwMilliseconds) == TRUE;
+#elif defined(__FreeBSD__)
+	(void)flags;
+	if (nsecs != DISPATCH_TIME_FOREVER) {
+		struct timespec ts = {
+			.tv_sec = (__typeof__(ts.tv_sec))(nsecs / NSEC_PER_SEC),
+			.tv_nsec = (__typeof__(ts.tv_nsec))(nsecs % NSEC_PER_SEC),
+		};
+		return _umtx_op((void*)address, UMTX_OP_WAIT_UINT, value, (void*)(uintptr_t)sizeof(struct timespec), (void*)&ts);
+	}
+	return _umtx_op((void*)address, UMTX_OP_WAIT_UINT, value, 0, 0);
 #else
 #error _dispatch_wait_on_address unimplemented for this platform
 #endif
@@ -553,6 +574,8 @@ _dispatch_wake_by_address(uint32_t volatile *address)
 	_dispatch_futex_wake((uint32_t *)address, INT_MAX, FUTEX_PRIVATE_FLAG);
 #elif defined(_WIN32)
 	WakeByAddressAll((uint32_t *)address);
+#elif defined(__FreeBSD__)
+	_umtx_op((void*)address, UMTX_OP_WAKE, INT_MAX, 0, 0);
 #else
 	(void)address;
 #endif
@@ -712,7 +735,7 @@ _dispatch_once_wait(dispatch_once_gate_t dgo)
 		_dispatch_futex_wait(lock, (dispatch_lock)new_v, NULL,
 				FUTEX_PRIVATE_FLAG);
 #else
-		_dispatch_thread_switch(new_v, 0, timeout++);
+		_dispatch_thread_switch((dispatch_lock)new_v, 0, timeout++);
 #endif
 		(void)timeout;
 	}
diff --git a/src/shims/lock.h b/src/shims/lock.h
index 0fcb65eb6..36ccc9920 100644
--- a/src/shims/lock.h
+++ b/src/shims/lock.h
@@ -79,6 +79,28 @@ _dispatch_lock_owner(dispatch_lock lock_value)
 	return lock_value & DLOCK_OWNER_MASK;
 }
 
+#elif defined(__FreeBSD__)
+
+#include <sys/types.h>
+#include <sys/umtx.h>
+#include <sched.h>
+
+typedef uint32_t dispatch_tid;
+typedef uint32_t dispatch_lock;
+
+#define DLOCK_OWNER_NULL			((dispatch_tid)0)
+#define DLOCK_OWNER_MASK			((dispatch_lock)0xfffffffc)
+#define DLOCK_WAITERS_BIT			((dispatch_lock)0x00000001)
+#define DLOCK_FAILED_TRYLOCK_BIT		((dispatch_lock)0x00000002)
+#define _dispatch_tid_self()			((dispatch_tid)(_dispatch_get_tsd_base()->tid << 2))
+
+DISPATCH_ALWAYS_INLINE
+static inline dispatch_tid
+_dispatch_lock_owner(dispatch_lock lock_value)
+{
+	return lock_value & DLOCK_OWNER_MASK;
+}
+
 #elif defined(_WIN32)
 
 #include <Windows.h>
diff --git a/src/swift/Source.swift b/src/swift/Source.swift
index f9c24280d..92201f8e0 100644
--- a/src/swift/Source.swift
+++ b/src/swift/Source.swift
@@ -124,8 +124,17 @@ extension DispatchSource {
 		public static let exit = ProcessEvent(rawValue: 0x80000000)
 		public static let fork = ProcessEvent(rawValue: 0x40000000)
 		public static let exec = ProcessEvent(rawValue: 0x20000000)
+#if os(FreeBSD)
+		public static let track = ProcessEvent(rawValue: 0x00000001)
+#else
 		public static let signal = ProcessEvent(rawValue: 0x08000000)
+#endif
+
+#if os(FreeBSD)
+		public static let all: ProcessEvent = [.exit, .fork, .exec, .track]
+#else
 		public static let all: ProcessEvent = [.exit, .fork, .exec, .signal]
+#endif
 	}
 #endif
 
@@ -224,7 +233,7 @@ extension DispatchSource {
 		return DispatchSource(source: source) as DispatchSourceUserDataReplace
 	}
 
-#if !os(Linux) && !os(Android) && !os(Windows) && !os(OpenBSD)
+#if !os(Linux) && !os(Android) && !os(Windows) && !os(OpenBSD) && !os(FreeBSD)
 	public class func makeFileSystemObjectSource(fileDescriptor: Int32, eventMask: FileSystemEvent, queue: DispatchQueue? = nil) -> DispatchSourceFileSystemObject {
 		let source = dispatch_source_create(_swift_dispatch_source_type_VNODE(), UInt(fileDescriptor), eventMask.rawValue, queue?.__wrapped)
 		return DispatchSource(source: source) as DispatchSourceFileSystemObject
@@ -293,7 +302,7 @@ extension DispatchSourceMemoryPressure {
 #if !os(Linux) && !os(Android) && !os(Windows) && !os(OpenBSD)
 extension DispatchSourceProcess {
 	public var handle: pid_t {
-		return pid_t(dispatch_source_get_handle(self as! DispatchSource))
+		return pid_t(CDispatch.dispatch_source_get_handle((self as! DispatchSource).__wrapped))
 	}
 
 	public var data: DispatchSource.ProcessEvent {
diff --git a/src/swift/Wrapper.swift b/src/swift/Wrapper.swift
index 63f76bcd9..1118bb6e4 100644
--- a/src/swift/Wrapper.swift
+++ b/src/swift/Wrapper.swift
@@ -183,8 +183,12 @@ extension DispatchSource : DispatchSourceMachSend,
 #endif
 
 #if !os(Linux) && !os(Android) && !os(Windows) && !os(OpenBSD)
-extension DispatchSource : DispatchSourceProcess,
-	DispatchSourceFileSystemObject {
+extension DispatchSource : DispatchSourceProcess {
+}
+#endif
+
+#if !os(Linux) && !os(Android) && !os(Windows) && !os(FreeBSD) && !os(OpenBSD)
+extension DispatchSource : DispatchSourceFileSystemObject {
 }
 #endif
 
diff --git a/src/swift/shims/DispatchOverlayShims.h b/src/swift/shims/DispatchOverlayShims.h
index 80e87a8db..5ed8dd228 100644
--- a/src/swift/shims/DispatchOverlayShims.h
+++ b/src/swift/shims/DispatchOverlayShims.h
@@ -88,6 +88,11 @@ SWIFT_DISPATCH_SOURCE_TYPE(PROC)
 SWIFT_DISPATCH_SOURCE_TYPE(VNODE)
 #endif
 
+#if defined(__FreeBSD__)
+SWIFT_DISPATCH_SOURCE_TYPE(PROC)
+SWIFT_DISPATCH_SOURCE_TYPE(VNODE)
+#endif
+
 extern void
 _swift_dispatch_source_create_abort(void);
 
diff --git a/tests/bsdtestharness.c b/tests/bsdtestharness.c
index 4b66c8956..5014cba37 100644
--- a/tests/bsdtestharness.c
+++ b/tests/bsdtestharness.c
@@ -212,7 +212,7 @@ main(int argc, char *argv[])
 #else
 	dispatch_queue_t main_q = dispatch_get_main_queue();
 
-	dispatch_source_t tmp_ds = dispatch_source_create(DISPATCH_SOURCE_TYPE_PROC, pid, DISPATCH_PROC_EXIT, main_q);
+	dispatch_source_t tmp_ds = dispatch_source_create(DISPATCH_SOURCE_TYPE_PROC, (uintptr_t)pid, DISPATCH_PROC_EXIT, main_q);
 	assert(tmp_ds);
 	dispatch_source_set_event_handler(tmp_ds, ^{
 		int status;
diff --git a/tests/dispatch_apply.c b/tests/dispatch_apply.c
index 1f2dfb470..01b3dfb65 100644
--- a/tests/dispatch_apply.c
+++ b/tests/dispatch_apply.c
@@ -81,7 +81,7 @@ static void busythread(void *ignored)
 static void test_apply_contended(dispatch_queue_t dq)
 {
 	uint32_t activecpu;
-#if defined(__linux__) || defined(__OpenBSD__)
+#if defined(__linux__) || defined(__OpenBSD__) || defined(__FreeBSD__)
 	activecpu = (uint32_t)sysconf(_SC_NPROCESSORS_ONLN);
 #elif defined(_WIN32)
 	SYSTEM_INFO si;
diff --git a/tests/dispatch_io_pipe.c b/tests/dispatch_io_pipe.c
index 50ddc8a87..eb32b6b87 100644
--- a/tests/dispatch_io_pipe.c
+++ b/tests/dispatch_io_pipe.c
@@ -90,6 +90,10 @@ test_get_pipe_buffer_size(int kind)
 		CloseHandle(write_handle);
 	});
 	return size;
+#elif defined(__FreeBSD__)
+	// buffer size of blocking and non-blocking pipes is different on FreeBSD
+	(void)kind;
+	return PIPE_BUF;
 #else
 	(void)kind;
 	static dispatch_once_t once;
diff --git a/tests/dispatch_select.c b/tests/dispatch_select.c
index 352157a6e..8a1147a5b 100644
--- a/tests/dispatch_select.c
+++ b/tests/dispatch_select.c
@@ -39,7 +39,7 @@ void finish(void* cxt);
 void
 stage1(int stage)
 {
-#if defined(_WIN32)
+#if defined(_WIN32) || defined(__FreeBSD__)
 	char *path = dispatch_test_get_large_file();
 	dispatch_fd_t fd = dispatch_test_fd_open(path, O_RDONLY);
 	if (fd == -1)