diff --git a/Cargo.toml b/Cargo.toml
index 491fa6038719f..024c79064c922 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -22,6 +22,7 @@ targets = [
     "aarch64-pc-windows-msvc",
     "aarch64-unknown-freebsd",
     "aarch64-unknown-fuchsia",
+    "aarch64-unknown-helenos",
     "aarch64-unknown-hermit",
     "aarch64-unknown-linux-gnu",
     "aarch64-unknown-linux-musl",
@@ -53,6 +54,7 @@ targets = [
     "i686-pc-windows-msvc",
     "i686-unknown-freebsd",
     "i686-unknown-haiku",
+    "i686-unknown-helenos",
     "i686-unknown-linux-gnu",
     "i686-unknown-linux-musl",
     "i686-unknown-netbsd",
@@ -68,6 +70,7 @@ targets = [
     "mipsel-unknown-linux-gnu",
     "mipsel-unknown-linux-musl",
     "nvptx64-nvidia-cuda",
+    "powerpc-unknown-helenos",
     "powerpc-unknown-linux-gnu",
     "powerpc-unknown-linux-gnuspe",
     "powerpc-unknown-netbsd",
@@ -94,6 +97,7 @@ targets = [
     "s390x-unknown-linux-gnu",
     "s390x-unknown-linux-musl",
     "sparc-unknown-linux-gnu",
+    "sparc64-unknown-helenos",
     "sparc64-unknown-linux-gnu",
     "sparc64-unknown-netbsd",
     "sparcv9-sun-solaris",
@@ -116,6 +120,7 @@ targets = [
     "x86_64-unknown-freebsd",
     "x86_64-unknown-fuchsia",
     "x86_64-unknown-haiku",
+    "x86_64-unknown-helenos",
     "x86_64-unknown-hermit",
     "x86_64-unknown-illumos",
     "x86_64-unknown-l4re-uclibc",
diff --git a/build.rs b/build.rs
index 0a3d39d16abb6..30f45a129153f 100644
--- a/build.rs
+++ b/build.rs
@@ -29,7 +29,7 @@ const CHECK_CFG_EXTRA: &[(&str, &[&str])] = &[
     (
         "target_os",
         &[
-            "switch", "aix", "ohos", "hurd", "rtems", "visionos", "nuttx", "cygwin",
+            "switch", "aix", "ohos", "hurd", "rtems", "visionos", "nuttx", "cygwin", "helenos",
         ],
     ),
     (
diff --git a/ci/verify-build.py b/ci/verify-build.py
index 483dc5cfa96fb..79c53f87a4ee1 100755
--- a/ci/verify-build.py
+++ b/ci/verify-build.py
@@ -137,6 +137,7 @@ def __post_init__(self):
     # there is no need to do this given the target tier policy, but the cost is small
     # and the saved churn from accidental breakage is significant, so we keep it around.
     Target("aarch64-unknown-freebsd", dist=False),
+    Target("aarch64-unknown-helenos", dist=False),
     Target("aarch64-unknown-hermit", dist=False),
     Target("aarch64-unknown-illumos", dist=False),
     Target("aarch64-unknown-netbsd", dist=False),
@@ -151,6 +152,7 @@ def __post_init__(self):
     Target("i386-apple-ios", dist=False),
     Target("i686-apple-darwin", dist=False),
     Target("i686-unknown-haiku", dist=False),
+    Target("i686-unknown-helenos", dist=False),
     Target("i686-unknown-hurd-gnu", dist=False),
     Target("i686-unknown-netbsd", dist=False),
     Target("i686-unknown-openbsd", dist=False),
@@ -164,6 +166,7 @@ def __post_init__(self):
     Target("mipsel-unknown-linux-gnu", dist=False),
     Target("mipsel-unknown-linux-musl", dist=False),
     Target("nvptx64-nvidia-cuda", dist=False),
+    Target("powerpc-unknown-helenos", dist=False),
     Target("powerpc-unknown-linux-gnuspe", dist=False),
     Target("powerpc-unknown-netbsd", dist=False),
     Target("powerpc-wrs-vxworks", dist=False),
@@ -185,6 +188,7 @@ def __post_init__(self):
     Target("riscv64imac-unknown-none-elf", dist=False),
     Target("s390x-unknown-linux-musl", dist=False),
     Target("sparc-unknown-linux-gnu", dist=False),
+    Target("sparc64-unknown-helenos", dist=False),
     Target("sparc64-unknown-netbsd", dist=False),
     Target("thumbv7em-none-eabihf", dist=False),
     Target("thumbv7m-none-eabi", dist=False),
@@ -193,6 +197,7 @@ def __post_init__(self):
     Target("thumbv8m.main-none-eabi", dist=False),
     Target("x86_64-unknown-dragonfly", dist=False),
     Target("x86_64-unknown-haiku", dist=False),
+    Target("x86_64-unknown-helenos", dist=False),
     Target("x86_64-unknown-hermit", dist=False),
     Target("x86_64-unknown-l4re-uclibc", dist=False),
     Target("x86_64-unknown-openbsd", dist=False),
diff --git a/src/helenos.rs b/src/helenos.rs
new file mode 100644
index 0000000000000..a8fa35eb963c8
--- /dev/null
+++ b/src/helenos.rs
@@ -0,0 +1,78 @@
+use crate::prelude::*;
+use crate::{
+    errno_t,
+    timespec,
+};
+
+pub type intmax_t = i64;
+pub type uintmax_t = u64;
+pub type intptr_t = isize;
+pub type uintptr_t = usize;
+pub type size_t = usize;
+pub type ssize_t = isize;
+
+// uspace/lib/posix/include/posix/pthread.h
+pub type pthread_key_t = c_int;
+
+// uspace/lib/posix/include/posix/sys/types.h
+pub type clockid_t = c_int;
+pub type pid_t = c_int;
+
+s! {
+    // common/include/adt/list.h
+    pub struct link_t {
+        pub next: *mut link_t,
+        pub prev: *mut link_t,
+    }
+
+    pub struct list_t {
+        pub head: link_t,
+    }
+}
+
+// uspace/lib/posix/include/posix/time.h
+pub const CLOCK_REALTIME: clockid_t = 0;
+pub const CLOCK_MONOTONIC: clockid_t = 1;
+
+// 'static inline' functions from libc
+// common/include/adt/list.h
+f! {
+    pub fn list_initialize(list: *mut list_t) -> () {
+        let list = &mut *list;
+        list.head.next = &mut list.head;
+        list.head.prev = &mut list.head;
+    }
+}
+
+extern "C" {
+    // common/include/str_error.h
+    pub fn str_error(err: errno_t) -> *const c_char;
+    pub fn str_error_name(err: errno_t) -> *const c_char;
+
+    // uspace/lib/posix/include/posix/pthread.h
+    pub fn pthread_key_create(
+        key: *mut pthread_key_t,
+        destructor: unsafe extern "C" fn(*mut c_void),
+    ) -> c_int;
+    pub fn pthread_getspecific(key: pthread_key_t) -> *mut c_void;
+    pub fn pthread_setspecific(key: pthread_key_t, value: *const c_void) -> c_int;
+    pub fn pthread_key_delete(key: pthread_key_t) -> c_int;
+
+    // uspace/lib/posix/include/posix/time.h
+    pub fn clock_getres(clock_id: clockid_t, res: *mut timespec) -> c_int;
+    pub fn clock_gettime(clock_id: clockid_t, tp: *mut timespec) -> c_int;
+    pub fn clock_settime(clock_id: clockid_t, tp: *const timespec) -> c_int;
+    pub fn clock_nanosleep(
+        clock_id: clockid_t,
+        flags: c_int,
+        rqtp: *const timespec,
+        rmtp: *mut timespec,
+    ) -> c_int;
+
+    // uspace/lib/posix/include/posix/unistd.h
+    pub fn getpid() -> pid_t;
+    pub fn getcwd(buf: *mut c_char, size: size_t) -> *mut c_char;
+    pub fn chdir(buf: *const c_char) -> c_int;
+    pub static environ: *const *const c_char;
+    pub fn isatty(fd: c_int) -> c_int;
+}
diff --git a/src/lib.rs b/src/lib.rs
index a29bf354f5f9d..2f499059630b6 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -93,6 +93,14 @@ cfg_if! {
         mod unix;
         pub use crate::unix::*;
 
+        prelude!();
+    } else if #[cfg(target_os = "helenos")] {
+        mod primitives;
+        pub use primitives::*;
+
+        mod helenos;
+        pub use self::helenos::*;
+
         prelude!();
     } else if #[cfg(target_os = "hermit")] {
         mod primitives;
diff --git a/src/new/helenos/abi/errno.rs b/src/new/helenos/abi/errno.rs
new file mode 100644
index 0000000000000..040298a720359
--- /dev/null
+++ b/src/new/helenos/abi/errno.rs
@@ -0,0 +1,43 @@
+//! HelenOS errno codes
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/abi/include/abi/errno.h>
+
+use crate::errno_t;
+
+pub const EOK: errno_t = 0;
+pub const ENOENT: errno_t = 1;
+pub const ENOMEM: errno_t = 2;
+pub const ELIMIT: errno_t = 3;
+pub const EREFUSED: errno_t = 4;
+pub const EFORWARD: errno_t = 5;
+pub const EPERM: errno_t = 6;
+pub const EHANGUP: errno_t = 7;
+pub const EPARTY: errno_t = 8;
+pub const EEXIST: errno_t = 9;
+pub const EBADMEM: errno_t = 10;
+pub const ENOTSUP: errno_t = 11;
+pub const EADDRNOTAVAIL: errno_t = 12;
+pub const ETIMEOUT: errno_t = 13;
+pub const EINVAL: errno_t = 14;
+pub const EBUSY: errno_t = 15;
+pub const EOVERFLOW: errno_t = 16;
+pub const EINTR: errno_t = 17;
+pub const EMFILE: errno_t = 18;
+pub const ENAMETOOLONG: errno_t = 19;
+pub const EISDIR: errno_t = 20;
+pub const ENOTDIR: errno_t = 21;
+pub const ENOSPC: errno_t = 22;
+pub const ENOTEMPTY: errno_t = 23;
+pub const EBADF: errno_t = 24;
+pub const EDOM: errno_t = 25;
+pub const ERANGE: errno_t = 26;
+pub const EXDEV: errno_t = 27;
+pub const EIO: errno_t = 28;
+pub const EMLINK: errno_t = 29;
+pub const ENXIO: errno_t = 30;
+pub const ENOFS: errno_t = 31;
+pub const EBADCHECKSUM: errno_t = 32;
+pub const ESTALL: errno_t = 33;
+pub const EEMPTY: errno_t = 34;
+pub const ENAK: errno_t = 35;
+pub const EAGAIN: errno_t = 36;
diff --git a/src/new/helenos/bits.rs b/src/new/helenos/bits.rs
new file mode 100644
index 0000000000000..bcb704d8cb038
--- /dev/null
+++ b/src/new/helenos/bits.rs
@@ -0,0 +1,9 @@
+//! HelenOS ABI bits
+//!
+//! * Headers: <https://github.com/HelenOS/helenos/tree/master/abi/include/_bits>
+
+// `errno.h`
+pub type errno_t = crate::c_int;
+
+// `native.h`
+pub type sysarg_t = crate::uintptr_t;
diff --git a/src/new/helenos/dirent_mod.rs b/src/new/helenos/dirent_mod.rs
new file mode 100644
index 0000000000000..089a5a5fbf3c6
--- /dev/null
+++ b/src/new/helenos/dirent_mod.rs
@@ -0,0 +1,29 @@
+//! HelenOS directory entry API
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/dirent.h>
+
+// The module is named to avoid name collision with the dirent struct, which causes issues with
+// wildcard imports in the parent module.
+
+use crate::{
+    c_char,
+    c_int,
+};
+
+s! {
+    pub struct dirent {
+        pub d_name: [c_char; 256],
+    }
+}
+
+extern_ty! {
+    pub enum DIR {}
+}
+
+extern "C" {
+    pub fn opendir(name: *const c_char) -> *mut DIR;
+    pub fn readdir(dir: *mut DIR) -> *mut dirent;
+    pub fn closedir(dir: *mut DIR) -> c_int;
+    pub fn rewinddir(dir: *mut DIR);
+
+}
diff --git a/src/new/helenos/errno.rs b/src/new/helenos/errno.rs
new file mode 100644
index 0000000000000..09b303fa5fa3e
--- /dev/null
+++ b/src/new/helenos/errno.rs
@@ -0,0 +1,7 @@
+//! HelenOS errno handling
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/errno.h>
+
+extern "C" {
+    pub fn __errno() -> *mut crate::errno_t;
+}
diff --git a/src/new/helenos/fibril.rs b/src/new/helenos/fibril.rs
new file mode 100644
index 0000000000000..e480a6ff994c5
--- /dev/null
+++ b/src/new/helenos/fibril.rs
@@ -0,0 +1,36 @@
+//! HelenOS fibrils API
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/fibril.h>
+
+pub use crate::time::*;
+use crate::{
+    c_void,
+    errno_t,
+    size_t,
+};
+
+pub type fid_t = *mut fibril_t;
+
+s! {
+    pub struct fibril_owner_info_t {
+        pub owned_by: *mut fibril_t,
+    }
+}
+
+extern_ty! {
+    pub enum fibril_t {}
+}
+
+extern "C" {
+    pub fn fibril_create_generic(
+        func: extern "C" fn(*mut c_void) -> errno_t,
+        arg: *mut c_void,
+        stacksize: size_t,
+    ) -> fid_t;
+    pub fn fibril_start(f: fid_t);
+    pub fn fibril_exit(retval: c_long) -> !;
+    pub fn fibril_detach(f: fid_t);
+    pub fn fibril_yield();
+    pub fn fibril_usleep(usec: usec_t);
+    pub fn fibril_get_id() -> fid_t;
+}
diff --git a/src/new/helenos/fibril_synch.rs b/src/new/helenos/fibril_synch.rs
new file mode 100644
index 0000000000000..0ad4fea2e1c09
--- /dev/null
+++ b/src/new/helenos/fibril_synch.rs
@@ -0,0 +1,49 @@
+//! HelenOS fibril synchronization primitives
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/fibril_synch.h>
+
+pub use crate::fibril::*;
+use crate::{
+    c_int,
+    errno_t,
+    list_initialize,
+    list_t,
+};
+
+s! {
+    pub struct fibril_mutex_t {
+        pub oi: fibril_owner_info_t,
+        pub counter: c_int,
+        pub waiters: list_t,
+    }
+
+    pub struct fibril_condvar_t {
+        pub waiters: list_t,
+    }
+}
+
+f! {
+    pub fn fibril_mutex_initialize(fm: *mut fibril_mutex_t) -> () {
+        let fm = &mut *fm;
+        fm.oi.owned_by = core::ptr::null_mut();
+        fm.counter = 1;
+        list_initialize(&mut fm.waiters);
+    }
+}
+
+extern "C" {
+    pub fn fibril_mutex_lock(mutex: *mut fibril_mutex_t);
+    pub fn fibril_mutex_unlock(mutex: *mut fibril_mutex_t);
+    pub fn fibril_mutex_trylock(mutex: *mut fibril_mutex_t) -> bool;
+    pub fn fibril_mutex_is_locked(mutex: *mut fibril_mutex_t) -> bool;
+
+    pub fn fibril_condvar_initialize(condvar: *mut fibril_condvar_t);
+    pub fn fibril_condvar_wait(condvar: *mut fibril_condvar_t, mutex: *mut fibril_mutex_t);
+    pub fn fibril_condvar_wait_timeout(
+        condvar: *mut fibril_condvar_t,
+        mutex: *mut fibril_mutex_t,
+        timeout: usec_t,
+    ) -> errno_t;
+    pub fn fibril_condvar_signal(condvar: *mut fibril_condvar_t);
+    pub fn fibril_condvar_broadcast(condvar: *mut fibril_condvar_t);
+}
diff --git a/src/new/helenos/inet/addr.rs b/src/new/helenos/inet/addr.rs
new file mode 100644
index 0000000000000..e00bb2b821e18
--- /dev/null
+++ b/src/new/helenos/inet/addr.rs
@@ -0,0 +1,26 @@
+//! HelenOS internet address types
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/inet/include/inet/addr.h>
+
+pub type addr32_t = u32;
+pub type addr128_t = [u8; 16];
+
+c_enum! {
+    #[repr(u32)]
+    pub enum ip_ver_t {
+        ip_any,
+        ip_v4,
+        ip_v6,
+    }
+}
+s_no_extra_traits! {
+    pub union __inet_addr_t_addr_union {
+        pub addr: addr32_t,
+        pub addr6: addr128_t,
+    }
+
+    pub struct inet_addr_t {
+        pub version: ip_ver_t,
+        pub addr: __inet_addr_t_addr_union,
+    }
+}
diff --git a/src/new/helenos/inet/dnsr.rs b/src/new/helenos/inet/dnsr.rs
new file mode 100644
index 0000000000000..05b81c52dbee5
--- /dev/null
+++ b/src/new/helenos/inet/dnsr.rs
@@ -0,0 +1,25 @@
+//! HelenOS DNS resolver API
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/inet/include/inet/dnsr.h>
+
+pub use crate::inet::addr::*;
+use crate::{
+    c_char,
+    errno_t,
+};
+
+s_no_extra_traits! {
+    pub struct dnsr_hostinfo_t {
+        pub cname: *mut c_char,
+        pub addr: inet_addr_t,
+    }
+}
+
+extern "C" {
+    pub fn dnsr_name2host(
+        name: *const c_char,
+        info: *mut *mut dnsr_hostinfo_t,
+        ipver: ip_ver_t,
+    ) -> errno_t;
+    pub fn dnsr_hostinfo_destroy(info: *mut dnsr_hostinfo_t);
+}
diff --git a/src/new/helenos/inet/endpoint.rs b/src/new/helenos/inet/endpoint.rs
new file mode 100644
index 0000000000000..2f8fecc88309d
--- /dev/null
+++ b/src/new/helenos/inet/endpoint.rs
@@ -0,0 +1,23 @@
+//! HelenOS internet endpoint types
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/inet/include/inet/endpoint.h>
+
+pub use crate::inet::addr::*;
+pub use crate::loc::*;
+
+s_no_extra_traits! {
+    pub struct inet_ep2_t {
+        pub local_link: service_id_t,
+        pub local: inet_ep_t,
+        pub remote: inet_ep_t,
+    }
+
+    pub struct inet_ep_t {
+        pub addr: inet_addr_t,
+        pub port: u16,
+    }
+}
+extern "C" {
+    pub fn inet_ep_init(ep: *mut inet_ep_t);
+    pub fn inet_ep2_init(epp: *mut inet_ep2_t);
+}
diff --git a/src/new/helenos/inet/tcp.rs b/src/new/helenos/inet/tcp.rs
new file mode 100644
index 0000000000000..2265058c2c9df
--- /dev/null
+++ b/src/new/helenos/inet/tcp.rs
@@ -0,0 +1,76 @@
+//! HelenOS TCP API
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/inet/include/inet/tcp.h>
+
+pub use crate::inet::endpoint::*;
+use crate::{
+    c_void,
+    errno_t,
+    size_t,
+};
+
+s_no_extra_traits! {
+    pub struct tcp_cb_t {
+        pub connected: extern "C" fn(conn: *mut tcp_conn_t),
+        pub conn_failed: extern "C" fn(conn: *mut tcp_conn_t),
+        pub conn_reset: extern "C" fn(conn: *mut tcp_conn_t),
+        pub data_avail: extern "C" fn(conn: *mut tcp_conn_t),
+        pub urg_data: extern "C" fn(conn: *mut tcp_conn_t),
+    }
+    pub struct tcp_listen_cb_t {
+        pub new_conn: extern "C" fn(listener: *mut tcp_listener_t, conn: *mut tcp_conn_t),
+    }
+}
+
+extern_ty! {
+    pub enum tcp_t {}
+    pub enum tcp_conn_t {}
+    pub enum tcp_listener_t {}
+}
+
+extern "C" {
+    pub fn tcp_create(tcp: *mut *mut tcp_t) -> errno_t;
+    pub fn tcp_destroy(tcp: *mut tcp_t);
+
+    pub fn tcp_conn_create(
+        tcp: *mut tcp_t,
+        epp: *mut inet_ep2_t,
+        callbacks: *mut tcp_cb_t,
+        arg: *mut c_void,
+        conn: *mut *mut tcp_conn_t,
+    ) -> errno_t;
+    pub fn tcp_conn_destroy(conn: *mut tcp_conn_t);
+
+    pub fn tcp_listener_create(
+        tcp: *mut tcp_t,
+        ep: *mut inet_ep_t,
+        listen_callbacks: *mut tcp_listen_cb_t,
+        listen_arg: *mut c_void,
+        conn_callbacks: *mut tcp_cb_t,
+        conn_arg: *mut c_void,
+        listener: *mut *mut tcp_listener_t,
+    ) -> errno_t;
+    pub fn tcp_listener_destroy(listener: *mut tcp_listener_t);
+
+    pub fn tcp_conn_userptr(conn: *mut tcp_conn_t) -> *mut c_void;
+    pub fn tcp_listener_userptr(listener: *mut tcp_listener_t) -> *mut c_void;
+
+    pub fn tcp_conn_wait_connected(conn: *mut tcp_conn_t) -> errno_t;
+    pub fn tcp_conn_send(conn: *mut tcp_conn_t, buf: *const c_void, len: size_t) -> errno_t;
+    pub fn tcp_conn_send_fin(conn: *mut tcp_conn_t) -> errno_t;
+    pub fn tcp_conn_push(conn: *mut tcp_conn_t) -> errno_t;
+    pub fn tcp_conn_reset(conn: *mut tcp_conn_t) -> errno_t;
+
+    pub fn tcp_conn_recv(
+        conn: *mut tcp_conn_t,
+        buf: *mut c_void,
+        bufsize: size_t,
+        received_len: *mut size_t,
+    ) -> errno_t;
+    pub fn tcp_conn_recv_wait(
+        conn: *mut tcp_conn_t,
+        buf: *mut c_void,
+        bufsize: size_t,
+        received_len: *mut size_t,
+    ) -> errno_t;
+}
diff --git a/src/new/helenos/ipc/mod.rs b/src/new/helenos/ipc/mod.rs
new file mode 100644
index 0000000000000..f7fa66ec789c3
--- /dev/null
+++ b/src/new/helenos/ipc/mod.rs
@@ -0,0 +1,12 @@
+//! HelenOS IPC types
+//!
+//! Headers: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/ipc>
+
+pub(crate) mod loc {
+    pub type service_id_t = crate::sysarg_t;
+}
+
+pub(crate) mod vfs {
+    pub type fs_handle_t = i16;
+    pub type fs_index_t = u32;
+}
diff --git a/src/new/helenos/loc.rs b/src/new/helenos/loc.rs
new file mode 100644
index 0000000000000..0cf367785713b
--- /dev/null
+++ b/src/new/helenos/loc.rs
@@ -0,0 +1,5 @@
+//! HelenOS libc/loc
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/loc.h>
+
+pub use crate::ipc::loc::*;
diff --git a/src/new/helenos/mod.rs b/src/new/helenos/mod.rs
new file mode 100644
index 0000000000000..5da156d05eda6
--- /dev/null
+++ b/src/new/helenos/mod.rs
@@ -0,0 +1,27 @@
+//! HelenOS libraries
+//!
+//! * HelenOS source tree: <https://github.com/HelenOS/helenos> (libraries are in uspace/lib, some bits are in abi and common)
+
+pub(crate) mod abi {
+    pub(crate) mod errno;
+}
+pub(crate) mod bits;
+pub(crate) mod dirent_mod;
+pub(crate) mod errno;
+pub(crate) mod fibril;
+pub(crate) mod fibril_synch;
+pub(crate) mod inet {
+    pub(crate) mod addr;
+    pub(crate) mod dnsr;
+    pub(crate) mod endpoint;
+    pub(crate) mod tcp;
+}
+pub(crate) mod ipc;
+pub(crate) mod loc;
+pub(crate) mod offset;
+pub(crate) mod stdio;
+pub(crate) mod stdlib;
+pub(crate) mod time;
+pub(crate) mod vfs {
+    pub(crate) mod vfs;
+}
diff --git a/src/new/helenos/offset.rs b/src/new/helenos/offset.rs
new file mode 100644
index 0000000000000..131d3d72f09ca
--- /dev/null
+++ b/src/new/helenos/offset.rs
@@ -0,0 +1,5 @@
+//! HelenOS libc offset types
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/offset.h>
+
+pub type aoff64_t = u64;
diff --git a/src/new/helenos/stdio.rs b/src/new/helenos/stdio.rs
new file mode 100644
index 0000000000000..953105fdc379d
--- /dev/null
+++ b/src/new/helenos/stdio.rs
@@ -0,0 +1,34 @@
+//! HelenOS libc standard I/O APIs
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/stdio.h>
+
+use crate::prelude::*;
+
+pub const SEEK_SET: c_int = 0;
+pub const SEEK_CUR: c_int = 1;
+pub const SEEK_END: c_int = 2;
+
+extern_ty! {
+    pub enum FILE {}
+}
+
+extern "C" {
+    pub static stdin: *mut FILE;
+    pub static stdout: *mut FILE;
+    pub static stderr: *mut FILE;
+
+    pub fn fputc(c: c_int, stream: *mut FILE) -> c_int;
+    pub fn fputs(s: *const c_char, stream: *mut FILE) -> c_int;
+
+    pub fn fopen(filename: *const c_char, mode: *const c_char) -> *mut FILE;
+    pub fn fclose(stream: *mut FILE) -> c_int;
+    pub fn fflush(stream: *mut FILE) -> c_int;
+
+    pub fn fread(buf: *mut c_void, size: size_t, nmemb: size_t, stream: *mut FILE) -> size_t;
+    pub fn fwrite(buf: *const c_void, size: size_t, nmemb: size_t, stream: *mut FILE) -> size_t;
+
+    pub fn fseek(stream: *mut FILE, offset: c_long, whence: c_int) -> c_int;
+    pub fn ftell(stream: *mut FILE) -> c_long;
+
+    pub fn fileno(stream: *mut FILE) -> c_int;
+}
diff --git a/src/new/helenos/stdlib.rs b/src/new/helenos/stdlib.rs
new file mode 100644
index 0000000000000..1f92a3de4fa55
--- /dev/null
+++ b/src/new/helenos/stdlib.rs
@@ -0,0 +1,18 @@
+use crate::prelude::*;
+
+extern "C" {
+    pub fn malloc(size: usize) -> *mut c_void;
+    pub fn calloc(nmemb: usize, size: usize) -> *mut c_void;
+    pub fn realloc(addr: *mut c_void, size: usize) -> *mut c_void;
+    pub fn free(addr: *mut c_void);
+
+    pub fn memalign(align: usize, size: usize) -> *mut c_void;
+
+    pub fn rand() -> c_int;
+    pub fn srand(seed: c_uint);
+
+    pub fn exit(code: c_int) -> !;
+    pub fn abort() -> !;
+
+    pub fn getenv(env: *const c_char) -> *mut c_char;
+}
diff --git a/src/new/helenos/time.rs b/src/new/helenos/time.rs
new file mode 100644
index 0000000000000..ef6b72d921a44
--- /dev/null
+++ b/src/new/helenos/time.rs
@@ -0,0 +1,22 @@
+//! HelenOS time handling
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/time.h>
+
+pub use crate::{
+    c_long,
+    c_longlong,
+};
+
+pub type time_t = c_longlong;
+pub type usec_t = c_longlong;
+
+s! {
+    pub struct timespec {
+        pub tv_sec: time_t,
+        pub tv_nsec: c_long,
+    }
+}
+
+extern "C" {
+    pub fn getuptime(tp: *mut timespec);
+}
diff --git a/src/new/helenos/vfs/vfs.rs b/src/new/helenos/vfs/vfs.rs
new file mode 100644
index 0000000000000..025d5ab9d213b
--- /dev/null
+++ b/src/new/helenos/vfs/vfs.rs
@@ -0,0 +1,47 @@
+//! HelenOS libc virtual file system APIs
+//!
+//! * Header file: <https://github.com/HelenOS/helenos/tree/master/uspace/lib/c/include/vfs/vfs.h>
+
+pub use crate::ipc::loc::*;
+pub use crate::ipc::vfs::*;
+pub use crate::offset::*;
+pub use crate::stdio::*;
+use crate::{
+    c_char,
+    c_int,
+    c_uint,
+    errno_t,
+};
+
+s! {
+    pub struct vfs_stat_t {
+        pub fs_handle: fs_handle_t,
+        pub service_id: service_id_t,
+        pub index: fs_index_t,
+        pub lnkcnt: c_uint,
+        pub is_file: bool,
+        pub is_directory: bool,
+        pub size: aoff64_t,
+        pub service: service_id_t,
+    }
+}
+
+c_enum! {
+    pub enum vfs_file_kind_t {
+        KIND_FILE,
+        KIND_DIRECTORY,
+    }
+}
+
+extern "C" {
+    pub fn vfs_fhandle(file: *mut FILE, handle: *mut c_int) -> errno_t;
+    pub fn vfs_stat(handle: c_int, stat: *mut vfs_stat_t) -> errno_t;
+    pub fn vfs_link_path(
+        path: *const c_char,
+        kind: vfs_file_kind_t,
+        linkedfd: *mut c_int,
+    ) -> errno_t;
+    pub fn vfs_unlink_path(path: *const c_char) -> errno_t;
+    pub fn vfs_rename_path(oldpath: *const c_char, newpath: *const c_char) -> errno_t;
+    pub fn vfs_stat_path(path: *const c_char, stat: *mut vfs_stat_t) -> errno_t;
+}
diff --git a/src/new/mod.rs b/src/new/mod.rs
index 38a0759afb65d..8591a3428f108 100644
--- a/src/new/mod.rs
+++ b/src/new/mod.rs
@@ -73,6 +73,9 @@ cfg_if! {
     } else if #[cfg(target_os = "haiku")] {
         mod haiku;
         pub(crate) use haiku::*;
+    } else if #[cfg(target_os = "helenos")] {
+        mod helenos;
+        pub(crate) use helenos::*;
     } else if #[cfg(target_os = "hermit")] {
         mod hermit_abi;
         // pub(crate) use hermit_abi::*;
@@ -193,6 +196,20 @@ cfg_if! {
         pub use utmpx_::*;
     } else if #[cfg(target_os = "openbsd")] {
         pub use sys::ipc::*;
+    } else if #[cfg(target_os = "helenos")] {
+        pub use abi::errno::*;
+        pub use bits::*;
+        pub use dirent_mod::*;
+        pub use errno::*;
+        pub use fibril::*;
+        pub use fibril_synch::*;
+        pub use inet::dnsr::*;
+        pub use inet::endpoint::*;
+        pub use inet::tcp::*;
+        pub use ipc::vfs::*;
+        pub use stdio::*;
+        pub use stdlib::*;
+        pub use vfs::vfs::*;
     }
 }