diff --git a/Cargo.lock b/Cargo.lock
index e229448df0477..55f986b60086c 100644
--- a/Cargo.lock
+++ b/Cargo.lock
@@ -1786,9 +1786,9 @@ checksum = "b294d6fa9ee409a054354afc4352b0b9ef7ca222c69b8812cbea9e7d2bf3783f"
 
 [[package]]
 name = "libc"
-version = "0.2.66"
+version = "0.2.69"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "d515b1f41455adea1313a4a2ac8a8a477634fbae63cc6100e3aebb207ce61558"
+checksum = "99e85c08494b21a9054e7fe1374a732aeadaff3980b6990b94bfd3a70f690005"
 dependencies = [
  "rustc-std-workspace-core",
 ]
@@ -4661,9 +4661,9 @@ checksum = "4ecf3b85f68e8abaa7555aa5abdb1153079387e60b718283d732f03897fcfc86"
 
 [[package]]
 name = "socket2"
-version = "0.3.11"
+version = "0.3.12"
 source = "registry+https://github.com/rust-lang/crates.io-index"
-checksum = "e8b74de517221a2cb01a53349cf54182acdc31a074727d3079068448c0676d85"
+checksum = "03088793f677dce356f3ccc2edb1b314ad191ab702a5de3faf49304f7e104918"
 dependencies = [
  "cfg-if",
  "libc",
diff --git a/src/librustc_codegen_ssa/Cargo.toml b/src/librustc_codegen_ssa/Cargo.toml
index 717e32d4a0d8a..d9620a21d37cd 100644
--- a/src/librustc_codegen_ssa/Cargo.toml
+++ b/src/librustc_codegen_ssa/Cargo.toml
@@ -15,7 +15,7 @@ cc = "1.0.1"
 num_cpus = "1.0"
 memmap = "0.7"
 log = "0.4.5"
-libc = "0.2.44"
+libc = "0.2.50"
 jobserver = "0.1.11"
 tempfile = "3.1"
 
diff --git a/src/librustc_codegen_ssa/back/link.rs b/src/librustc_codegen_ssa/back/link.rs
index d58d9b91c73ac..4c66d901e7a99 100644
--- a/src/librustc_codegen_ssa/back/link.rs
+++ b/src/librustc_codegen_ssa/back/link.rs
@@ -761,7 +761,7 @@ fn linker_and_flavor(sess: &Session) -> (PathBuf, LinkerFlavor) {
                         }
                     }
                     LinkerFlavor::Gcc => {
-                        if cfg!(target_os = "solaris") {
+                        if cfg!(any(target_os = "solaris", target_os = "illumos")) {
                             // On historical Solaris systems, "cc" may have
                             // been Sun Studio, which is not flag-compatible
                             // with "gcc".  This history casts a long shadow,
diff --git a/src/librustc_target/spec/illumos_base.rs b/src/librustc_target/spec/illumos_base.rs
new file mode 100644
index 0000000000000..35ac346fb3f6f
--- /dev/null
+++ b/src/librustc_target/spec/illumos_base.rs
@@ -0,0 +1,48 @@
+use crate::spec::{LinkArgs, LinkerFlavor, TargetOptions};
+use std::default::Default;
+
+pub fn opts() -> TargetOptions {
+    let mut late_link_args = LinkArgs::new();
+    late_link_args.insert(
+        LinkerFlavor::Gcc,
+        vec![
+            // LLVM will insert calls to the stack protector functions
+            // "__stack_chk_fail" and "__stack_chk_guard" into code in native
+            // object files.  Some platforms include these symbols directly in
+            // libc, but at least historically these have been provided in
+            // libssp.so on illumos and Solaris systems.
+            "-lssp".to_string(),
+        ],
+    );
+
+    TargetOptions {
+        dynamic_linking: true,
+        executables: true,
+        has_rpath: true,
+        target_family: Some("unix".to_string()),
+        is_like_solaris: true,
+        limit_rdylib_exports: false, // Linker doesn't support this
+        eliminate_frame_pointer: false,
+        late_link_args,
+
+        // While we support ELF TLS, rust requires a way to register
+        // cleanup handlers (in C, this would be something along the lines of:
+        // void register_callback(void (*fn)(void *), void *arg);
+        // (see src/libstd/sys/unix/fast_thread_local.rs) that is currently
+        // missing in illumos.  For now at least, we must fallback to using
+        // pthread_{get,set}specific.
+        //has_elf_tls: true,
+
+        // FIXME: Currently, rust is invoking cc to link, which ends up
+        // causing these to get included twice.  We should eventually transition
+        // to having rustc invoke ld directly, in which case these will need to
+        // be uncommented.
+        //
+        // We want XPG6 behavior from libc and libm.  See standards(5)
+        //pre_link_objects_exe: vec![
+        //    "/usr/lib/amd64/values-Xc.o".to_string(),
+        //    "/usr/lib/amd64/values-xpg6.o".to_string(),
+        //],
+        ..Default::default()
+    }
+}
diff --git a/src/librustc_target/spec/mod.rs b/src/librustc_target/spec/mod.rs
index 6ff812754aa7d..8f3097ad4233e 100644
--- a/src/librustc_target/spec/mod.rs
+++ b/src/librustc_target/spec/mod.rs
@@ -55,6 +55,7 @@ mod fuchsia_base;
 mod haiku_base;
 mod hermit_base;
 mod hermit_kernel_base;
+mod illumos_base;
 mod l4re_base;
 mod linux_base;
 mod linux_kernel_base;
@@ -438,6 +439,8 @@ supported_targets! {
     ("x86_64-sun-solaris", "x86_64-pc-solaris", x86_64_sun_solaris),
     ("sparcv9-sun-solaris", sparcv9_sun_solaris),
 
+    ("x86_64-unknown-illumos", x86_64_unknown_illumos),
+
     ("x86_64-pc-windows-gnu", x86_64_pc_windows_gnu),
     ("i686-pc-windows-gnu", i686_pc_windows_gnu),
     ("i686-uwp-windows-gnu", i686_uwp_windows_gnu),
diff --git a/src/librustc_target/spec/x86_64_unknown_illumos.rs b/src/librustc_target/spec/x86_64_unknown_illumos.rs
new file mode 100644
index 0000000000000..8d461f67397f2
--- /dev/null
+++ b/src/librustc_target/spec/x86_64_unknown_illumos.rs
@@ -0,0 +1,24 @@
+use crate::spec::{LinkerFlavor, Target, TargetResult};
+
+pub fn target() -> TargetResult {
+    let mut base = super::illumos_base::opts();
+    base.pre_link_args.insert(LinkerFlavor::Gcc, vec!["-m64".to_string(), "-std=c99".to_string()]);
+    base.cpu = "x86-64".to_string();
+    base.max_atomic_width = Some(64);
+
+    Ok(Target {
+        // LLVM does not currently have a separate illumos target,
+        // so we still pass Solaris to it
+        llvm_target: "x86_64-pc-solaris".to_string(),
+        target_endian: "little".to_string(),
+        target_pointer_width: "64".to_string(),
+        target_c_int_width: "32".to_string(),
+        data_layout: "e-m:e-i64:64-f80:128-n8:16:32:64-S128".to_string(),
+        arch: "x86_64".to_string(),
+        target_os: "illumos".to_string(),
+        target_env: String::new(),
+        target_vendor: "unknown".to_string(),
+        linker_flavor: LinkerFlavor::Gcc,
+        options: base,
+    })
+}
diff --git a/src/librustdoc/clean/cfg.rs b/src/librustdoc/clean/cfg.rs
index 775d600fc3d4b..57d499e38a77b 100644
--- a/src/librustdoc/clean/cfg.rs
+++ b/src/librustdoc/clean/cfg.rs
@@ -360,6 +360,7 @@ impl<'a> fmt::Display for Html<'a> {
                         "fuchsia" => "Fuchsia",
                         "haiku" => "Haiku",
                         "hermit" => "HermitCore",
+                        "illumos" => "illumos",
                         "ios" => "iOS",
                         "l4re" => "L4Re",
                         "linux" => "Linux",
diff --git a/src/libstd/build.rs b/src/libstd/build.rs
index 8db7bc12cd308..743a1778fbda3 100644
--- a/src/libstd/build.rs
+++ b/src/libstd/build.rs
@@ -25,6 +25,14 @@ fn main() {
         println!("cargo:rustc-link-lib=posix4");
         println!("cargo:rustc-link-lib=pthread");
         println!("cargo:rustc-link-lib=resolv");
+    } else if target.contains("illumos") {
+        println!("cargo:rustc-link-lib=socket");
+        println!("cargo:rustc-link-lib=posix4");
+        println!("cargo:rustc-link-lib=pthread");
+        println!("cargo:rustc-link-lib=resolv");
+        println!("cargo:rustc-link-lib=nsl");
+        // Use libumem for the (malloc-compatible) allocator
+        println!("cargo:rustc-link-lib=umem");
     } else if target.contains("apple-darwin") {
         println!("cargo:rustc-link-lib=System");
 
diff --git a/src/libstd/f64.rs b/src/libstd/f64.rs
index ff222fc8539d0..5cf9cb73d4bf9 100644
--- a/src/libstd/f64.rs
+++ b/src/libstd/f64.rs
@@ -919,7 +919,7 @@ impl f64 {
     // because of their non-standard behavior (e.g., log(-n) returns -Inf instead
     // of expected NaN).
     fn log_wrapper<F: Fn(f64) -> f64>(self, log_fn: F) -> f64 {
-        if !cfg!(target_os = "solaris") {
+        if !cfg!(any(target_os = "solaris", target_os = "illumos")) {
             log_fn(self)
         } else {
             if self.is_finite() {
diff --git a/src/libstd/os/illumos/fs.rs b/src/libstd/os/illumos/fs.rs
new file mode 100644
index 0000000000000..2abbf1fa9fa16
--- /dev/null
+++ b/src/libstd/os/illumos/fs.rs
@@ -0,0 +1,118 @@
+#![stable(feature = "metadata_ext", since = "1.1.0")]
+
+use libc;
+
+use crate::fs::Metadata;
+use crate::sys_common::AsInner;
+
+#[allow(deprecated)]
+use crate::os::illumos::raw;
+
+/// OS-specific extensions to [`fs::Metadata`].
+///
+/// [`fs::Metadata`]: ../../../../std/fs/struct.Metadata.html
+#[stable(feature = "metadata_ext", since = "1.1.0")]
+pub trait MetadataExt {
+    /// Gain a reference to the underlying `stat` structure which contains
+    /// the raw information returned by the OS.
+    ///
+    /// The contents of the returned `stat` are **not** consistent across
+    /// Unix platforms. The `os::unix::fs::MetadataExt` trait contains the
+    /// cross-Unix abstractions contained within the raw stat.
+    #[stable(feature = "metadata_ext", since = "1.1.0")]
+    #[rustc_deprecated(
+        since = "1.8.0",
+        reason = "deprecated in favor of the accessor methods of this trait"
+    )]
+    #[allow(deprecated)]
+    fn as_raw_stat(&self) -> &raw::stat;
+
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_dev(&self) -> u64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_ino(&self) -> u64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_mode(&self) -> u32;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_nlink(&self) -> u64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_uid(&self) -> u32;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_gid(&self) -> u32;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_rdev(&self) -> u64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_size(&self) -> u64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_atime(&self) -> i64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_atime_nsec(&self) -> i64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_mtime(&self) -> i64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_mtime_nsec(&self) -> i64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_ctime(&self) -> i64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_ctime_nsec(&self) -> i64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_blksize(&self) -> u64;
+    #[stable(feature = "metadata_ext2", since = "1.8.0")]
+    fn st_blocks(&self) -> u64;
+}
+
+#[stable(feature = "metadata_ext", since = "1.1.0")]
+impl MetadataExt for Metadata {
+    #[allow(deprecated)]
+    fn as_raw_stat(&self) -> &raw::stat {
+        unsafe { &*(self.as_inner().as_inner() as *const libc::stat as *const raw::stat) }
+    }
+    fn st_dev(&self) -> u64 {
+        self.as_inner().as_inner().st_dev as u64
+    }
+    fn st_ino(&self) -> u64 {
+        self.as_inner().as_inner().st_ino as u64
+    }
+    fn st_mode(&self) -> u32 {
+        self.as_inner().as_inner().st_mode as u32
+    }
+    fn st_nlink(&self) -> u64 {
+        self.as_inner().as_inner().st_nlink as u64
+    }
+    fn st_uid(&self) -> u32 {
+        self.as_inner().as_inner().st_uid as u32
+    }
+    fn st_gid(&self) -> u32 {
+        self.as_inner().as_inner().st_gid as u32
+    }
+    fn st_rdev(&self) -> u64 {
+        self.as_inner().as_inner().st_rdev as u64
+    }
+    fn st_size(&self) -> u64 {
+        self.as_inner().as_inner().st_size as u64
+    }
+    fn st_atime(&self) -> i64 {
+        self.as_inner().as_inner().st_atime as i64
+    }
+    fn st_atime_nsec(&self) -> i64 {
+        self.as_inner().as_inner().st_atime_nsec as i64
+    }
+    fn st_mtime(&self) -> i64 {
+        self.as_inner().as_inner().st_mtime as i64
+    }
+    fn st_mtime_nsec(&self) -> i64 {
+        self.as_inner().as_inner().st_mtime_nsec as i64
+    }
+    fn st_ctime(&self) -> i64 {
+        self.as_inner().as_inner().st_ctime as i64
+    }
+    fn st_ctime_nsec(&self) -> i64 {
+        self.as_inner().as_inner().st_ctime_nsec as i64
+    }
+    fn st_blksize(&self) -> u64 {
+        self.as_inner().as_inner().st_blksize as u64
+    }
+    fn st_blocks(&self) -> u64 {
+        self.as_inner().as_inner().st_blocks as u64
+    }
+}
diff --git a/src/libstd/os/illumos/mod.rs b/src/libstd/os/illumos/mod.rs
new file mode 100644
index 0000000000000..e61926f89356a
--- /dev/null
+++ b/src/libstd/os/illumos/mod.rs
@@ -0,0 +1,6 @@
+//! illumos-specific definitions
+
+#![stable(feature = "raw_ext", since = "1.1.0")]
+
+pub mod fs;
+pub mod raw;
diff --git a/src/libstd/os/illumos/raw.rs b/src/libstd/os/illumos/raw.rs
new file mode 100644
index 0000000000000..88c832ae7c773
--- /dev/null
+++ b/src/libstd/os/illumos/raw.rs
@@ -0,0 +1,74 @@
+//! illumos-specific raw type definitions
+
+#![stable(feature = "raw_ext", since = "1.1.0")]
+#![rustc_deprecated(
+    since = "1.8.0",
+    reason = "these type aliases are no longer supported by the standard library, the `libc` \
+    crate on crates.io should be used instead for the correct definitions"
+)]
+#![allow(deprecated)]
+
+use crate::os::raw::c_long;
+use crate::os::unix::raw::{gid_t, uid_t};
+
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type blkcnt_t = u64;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type blksize_t = u64;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type dev_t = u64;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type fflags_t = u32;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type ino_t = u64;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type mode_t = u32;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type nlink_t = u64;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type off_t = u64;
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub type time_t = i64;
+
+#[stable(feature = "pthread_t", since = "1.8.0")]
+pub type pthread_t = u32;
+
+#[repr(C)]
+#[derive(Clone)]
+#[stable(feature = "raw_ext", since = "1.1.0")]
+pub struct stat {
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_dev: dev_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_ino: ino_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_mode: mode_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_nlink: nlink_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_uid: uid_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_gid: gid_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_rdev: dev_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_size: off_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_atime: time_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_atime_nsec: c_long,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_mtime: time_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_mtime_nsec: c_long,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_ctime: time_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_ctime_nsec: c_long,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_blksize: blksize_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub st_blocks: blkcnt_t,
+    #[stable(feature = "raw_ext", since = "1.1.0")]
+    pub __unused: [u8; 16],
+}
diff --git a/src/libstd/os/mod.rs b/src/libstd/os/mod.rs
index 0fa4a1d2353ca..fd6ee088e961c 100644
--- a/src/libstd/os/mod.rs
+++ b/src/libstd/os/mod.rs
@@ -52,6 +52,8 @@ pub mod freebsd;
 pub mod fuchsia;
 #[cfg(target_os = "haiku")]
 pub mod haiku;
+#[cfg(target_os = "illumos")]
+pub mod illumos;
 #[cfg(target_os = "ios")]
 pub mod ios;
 #[cfg(target_os = "macos")]
diff --git a/src/libstd/sys/unix/alloc.rs b/src/libstd/sys/unix/alloc.rs
index 77417e4133127..8e193935460eb 100644
--- a/src/libstd/sys/unix/alloc.rs
+++ b/src/libstd/sys/unix/alloc.rs
@@ -52,7 +52,12 @@ unsafe impl GlobalAlloc for System {
     }
 }
 
-#[cfg(any(target_os = "android", target_os = "redox", target_os = "solaris"))]
+#[cfg(any(
+    target_os = "android",
+    target_os = "illumos",
+    target_os = "redox",
+    target_os = "solaris"
+))]
 #[inline]
 unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
     // On android we currently target API level 9 which unfortunately
@@ -75,7 +80,12 @@ unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
     libc::memalign(layout.align(), layout.size()) as *mut u8
 }
 
-#[cfg(not(any(target_os = "android", target_os = "redox", target_os = "solaris")))]
+#[cfg(not(any(
+    target_os = "android",
+    target_os = "illumos",
+    target_os = "redox",
+    target_os = "solaris"
+)))]
 #[inline]
 unsafe fn aligned_malloc(layout: &Layout) -> *mut u8 {
     let mut out = ptr::null_mut();
diff --git a/src/libstd/sys/unix/args.rs b/src/libstd/sys/unix/args.rs
index 09acc3f6e3ea8..4c3e8542d576d 100644
--- a/src/libstd/sys/unix/args.rs
+++ b/src/libstd/sys/unix/args.rs
@@ -65,6 +65,7 @@ impl DoubleEndedIterator for Args {
     target_os = "netbsd",
     target_os = "openbsd",
     target_os = "solaris",
+    target_os = "illumos",
     target_os = "emscripten",
     target_os = "haiku",
     target_os = "l4re",
diff --git a/src/libstd/sys/unix/env.rs b/src/libstd/sys/unix/env.rs
index 984bcfa45099b..7f5e9b04dba4b 100644
--- a/src/libstd/sys/unix/env.rs
+++ b/src/libstd/sys/unix/env.rs
@@ -97,6 +97,17 @@ pub mod os {
     pub const EXE_EXTENSION: &str = "";
 }
 
+#[cfg(target_os = "illumos")]
+pub mod os {
+    pub const FAMILY: &str = "unix";
+    pub const OS: &str = "illumos";
+    pub const DLL_PREFIX: &str = "lib";
+    pub const DLL_SUFFIX: &str = ".so";
+    pub const DLL_EXTENSION: &str = "so";
+    pub const EXE_SUFFIX: &str = "";
+    pub const EXE_EXTENSION: &str = "";
+}
+
 #[cfg(target_os = "haiku")]
 pub mod os {
     pub const FAMILY: &str = "unix";
diff --git a/src/libstd/sys/unix/fd.rs b/src/libstd/sys/unix/fd.rs
index 8a99836912a33..1bba56e334a2e 100644
--- a/src/libstd/sys/unix/fd.rs
+++ b/src/libstd/sys/unix/fd.rs
@@ -153,6 +153,7 @@ impl FileDesc {
     #[cfg(not(any(
         target_env = "newlib",
         target_os = "solaris",
+        target_os = "illumos",
         target_os = "emscripten",
         target_os = "fuchsia",
         target_os = "l4re",
@@ -169,6 +170,7 @@ impl FileDesc {
     #[cfg(any(
         target_env = "newlib",
         target_os = "solaris",
+        target_os = "illumos",
         target_os = "emscripten",
         target_os = "fuchsia",
         target_os = "l4re",
diff --git a/src/libstd/sys/unix/fs.rs b/src/libstd/sys/unix/fs.rs
index ab2a871b92df4..a233aa47dff58 100644
--- a/src/libstd/sys/unix/fs.rs
+++ b/src/libstd/sys/unix/fs.rs
@@ -22,6 +22,7 @@ use libc::fstatat64;
     target_os = "linux",
     target_os = "emscripten",
     target_os = "solaris",
+    target_os = "illumos",
     target_os = "l4re",
     target_os = "fuchsia",
     target_os = "redox"
@@ -200,7 +201,12 @@ pub struct DirEntry {
     // on Solaris and Fuchsia because a) it uses a zero-length
     // array to store the name, b) its lifetime between readdir
     // calls is not guaranteed.
-    #[cfg(any(target_os = "solaris", target_os = "fuchsia", target_os = "redox"))]
+    #[cfg(any(
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "fuchsia",
+        target_os = "redox"
+    ))]
     name: Box<[u8]>,
 }
 
@@ -403,7 +409,12 @@ impl fmt::Debug for ReadDir {
 impl Iterator for ReadDir {
     type Item = io::Result<DirEntry>;
 
-    #[cfg(any(target_os = "solaris", target_os = "fuchsia", target_os = "redox"))]
+    #[cfg(any(
+        target_os = "solaris",
+        target_os = "fuchsia",
+        target_os = "redox",
+        target_os = "illumos"
+    ))]
     fn next(&mut self) -> Option<io::Result<DirEntry>> {
         use crate::slice;
 
@@ -441,7 +452,12 @@ impl Iterator for ReadDir {
         }
     }
 
-    #[cfg(not(any(target_os = "solaris", target_os = "fuchsia", target_os = "redox")))]
+    #[cfg(not(any(
+        target_os = "solaris",
+        target_os = "fuchsia",
+        target_os = "redox",
+        target_os = "illumos"
+    )))]
     fn next(&mut self) -> Option<io::Result<DirEntry>> {
         if self.end_of_stream {
             return None;
@@ -514,12 +530,12 @@ impl DirEntry {
         lstat(&self.path())
     }
 
-    #[cfg(any(target_os = "solaris", target_os = "haiku"))]
+    #[cfg(any(target_os = "solaris", target_os = "illumos", target_os = "haiku"))]
     pub fn file_type(&self) -> io::Result<FileType> {
         lstat(&self.path()).map(|m| m.file_type())
     }
 
-    #[cfg(not(any(target_os = "solaris", target_os = "haiku")))]
+    #[cfg(not(any(target_os = "solaris", target_os = "illumos", target_os = "haiku")))]
     pub fn file_type(&self) -> io::Result<FileType> {
         match self.entry.d_type {
             libc::DT_CHR => Ok(FileType { mode: libc::S_IFCHR }),
@@ -540,6 +556,7 @@ impl DirEntry {
         target_os = "emscripten",
         target_os = "android",
         target_os = "solaris",
+        target_os = "illumos",
         target_os = "haiku",
         target_os = "l4re",
         target_os = "fuchsia",
@@ -586,7 +603,12 @@ impl DirEntry {
     fn name_bytes(&self) -> &[u8] {
         unsafe { CStr::from_ptr(self.entry.d_name.as_ptr()).to_bytes() }
     }
-    #[cfg(any(target_os = "solaris", target_os = "fuchsia", target_os = "redox"))]
+    #[cfg(any(
+        target_os = "solaris",
+        target_os = "illumos",
+        target_os = "fuchsia",
+        target_os = "redox"
+    ))]
     fn name_bytes(&self) -> &[u8] {
         &*self.name
     }
diff --git a/src/libstd/sys/unix/mod.rs b/src/libstd/sys/unix/mod.rs
index fbcb006ecdf11..0154609d939f3 100644
--- a/src/libstd/sys/unix/mod.rs
+++ b/src/libstd/sys/unix/mod.rs
@@ -17,6 +17,8 @@ pub use crate::os::freebsd as platform;
 pub use crate::os::fuchsia as platform;
 #[cfg(all(not(doc), target_os = "haiku"))]
 pub use crate::os::haiku as platform;
+#[cfg(all(not(doc), target_os = "illumos"))]
+pub use crate::os::illumos as platform;
 #[cfg(all(not(doc), target_os = "ios"))]
 pub use crate::os::ios as platform;
 #[cfg(all(not(doc), target_os = "l4re"))]
diff --git a/src/libstd/sys/unix/net.rs b/src/libstd/sys/unix/net.rs
index b37675e0a0a00..d18c22b0573f3 100644
--- a/src/libstd/sys/unix/net.rs
+++ b/src/libstd/sys/unix/net.rs
@@ -322,11 +322,19 @@ impl Socket {
         Ok(raw != 0)
     }
 
+    #[cfg(not(any(target_os = "solaris", target_os = "illumos")))]
     pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
         let mut nonblocking = nonblocking as libc::c_int;
         cvt(unsafe { libc::ioctl(*self.as_inner(), libc::FIONBIO, &mut nonblocking) }).map(drop)
     }
 
+    #[cfg(any(target_os = "solaris", target_os = "illumos"))]
+    pub fn set_nonblocking(&self, nonblocking: bool) -> io::Result<()> {
+        // FIONBIO is inadequate for sockets on illumos/Solaris, so use the
+        // fcntl(F_[GS]ETFL)-based method provided by FileDesc instead.
+        self.0.set_nonblocking(nonblocking)
+    }
+
     pub fn take_error(&self) -> io::Result<Option<io::Error>> {
         let raw: c_int = getsockopt(self, libc::SOL_SOCKET, libc::SO_ERROR)?;
         if raw == 0 { Ok(None) } else { Ok(Some(io::Error::from_raw_os_error(raw as i32))) }
diff --git a/src/libstd/sys/unix/os.rs b/src/libstd/sys/unix/os.rs
index 91f7d1524ccef..a9cd5094997bd 100644
--- a/src/libstd/sys/unix/os.rs
+++ b/src/libstd/sys/unix/os.rs
@@ -54,7 +54,7 @@ extern "C" {
         ),
         link_name = "__errno"
     )]
-    #[cfg_attr(target_os = "solaris", link_name = "___errno")]
+    #[cfg_attr(any(target_os = "solaris", target_os = "illumos"), link_name = "___errno")]
     #[cfg_attr(
         any(target_os = "macos", target_os = "ios", target_os = "freebsd"),
         link_name = "__error"
@@ -357,7 +357,7 @@ pub fn current_exe() -> io::Result<PathBuf> {
     }
 }
 
-#[cfg(any(target_os = "solaris"))]
+#[cfg(any(target_os = "solaris", target_os = "illumos"))]
 pub fn current_exe() -> io::Result<PathBuf> {
     extern "C" {
         fn getexecname() -> *const c_char;
diff --git a/src/libstd/sys/unix/stack_overflow.rs b/src/libstd/sys/unix/stack_overflow.rs
index 2626ca37cf8b8..5e10357835056 100644
--- a/src/libstd/sys/unix/stack_overflow.rs
+++ b/src/libstd/sys/unix/stack_overflow.rs
@@ -33,6 +33,7 @@ impl Drop for Handler {
     target_os = "dragonfly",
     target_os = "freebsd",
     target_os = "solaris",
+    target_os = "illumos",
     all(target_os = "netbsd", not(target_vendor = "rumprun")),
     target_os = "openbsd"
 ))]
@@ -162,7 +163,8 @@ mod imp {
         target_os = "freebsd",
         target_os = "netbsd",
         target_os = "openbsd",
-        target_os = "solaris"
+        target_os = "solaris",
+        target_os = "illumos"
     ))]
     unsafe fn get_stack() -> libc::stack_t {
         libc::stack_t { ss_sp: get_stackp(), ss_flags: 0, ss_size: SIGSTKSZ }
@@ -214,6 +216,7 @@ mod imp {
     target_os = "dragonfly",
     target_os = "freebsd",
     target_os = "solaris",
+    target_os = "illumos",
     all(target_os = "netbsd", not(target_vendor = "rumprun")),
     target_os = "openbsd"
 )))]
diff --git a/src/libstd/sys/unix/thread.rs b/src/libstd/sys/unix/thread.rs
index aab5a92a7ad2a..895ea48e2b43e 100644
--- a/src/libstd/sys/unix/thread.rs
+++ b/src/libstd/sys/unix/thread.rs
@@ -132,7 +132,7 @@ impl Thread {
         }
     }
 
-    #[cfg(target_os = "solaris")]
+    #[cfg(any(target_os = "solaris", target_os = "illumos"))]
     pub fn set_name(name: &CStr) {
         weak! {
             fn pthread_setname_np(
@@ -155,7 +155,7 @@ impl Thread {
         target_os = "redox"
     ))]
     pub fn set_name(_name: &CStr) {
-        // Newlib, Illumos, Haiku, and Emscripten have no way to set a thread name.
+        // Newlib, Haiku, and Emscripten have no way to set a thread name.
     }
     #[cfg(target_os = "fuchsia")]
     pub fn set_name(_name: &CStr) {
diff --git a/src/libstd/sys_common/net.rs b/src/libstd/sys_common/net.rs
index 135e8308afaea..cdd3d2edf1fa1 100644
--- a/src/libstd/sys_common/net.rs
+++ b/src/libstd/sys_common/net.rs
@@ -17,7 +17,7 @@ cfg_if::cfg_if! {
     if #[cfg(any(
         target_os = "dragonfly", target_os = "freebsd",
         target_os = "ios", target_os = "macos",
-        target_os = "openbsd", target_os = "netbsd",
+        target_os = "openbsd", target_os = "netbsd", target_os = "illumos",
         target_os = "solaris", target_os = "haiku", target_os = "l4re"))] {
         use crate::sys::net::netc::IPV6_JOIN_GROUP as IPV6_ADD_MEMBERSHIP;
         use crate::sys::net::netc::IPV6_LEAVE_GROUP as IPV6_DROP_MEMBERSHIP;
@@ -43,7 +43,7 @@ cfg_if::cfg_if! {
     if #[cfg(any(
         target_os = "dragonfly", target_os = "freebsd",
         target_os = "openbsd", target_os = "netbsd",
-        target_os = "solaris"))] {
+        target_os = "solaris", target_os = "illumos"))] {
         use libc::c_uchar;
         type IpV4MultiCastType = c_uchar;
     } else {
diff --git a/src/libtest/helpers/concurrency.rs b/src/libtest/helpers/concurrency.rs
index 6b0c8a8af32b4..e8f3820558a6d 100644
--- a/src/libtest/helpers/concurrency.rs
+++ b/src/libtest/helpers/concurrency.rs
@@ -77,6 +77,7 @@ pub fn get_concurrency() -> usize {
         target_os = "linux",
         target_os = "macos",
         target_os = "solaris",
+        target_os = "illumos",
     ))]
     fn num_cpus() -> usize {
         unsafe { libc::sysconf(libc::_SC_NPROCESSORS_ONLN) as usize }
diff --git a/src/libunwind/build.rs b/src/libunwind/build.rs
index 0628e5d2fc03a..c8d2419ab4514 100644
--- a/src/libunwind/build.rs
+++ b/src/libunwind/build.rs
@@ -30,6 +30,8 @@ fn main() {
         }
     } else if target.contains("solaris") {
         println!("cargo:rustc-link-lib=gcc_s");
+    } else if target.contains("illumos") {
+        println!("cargo:rustc-link-lib=gcc_s");
     } else if target.contains("dragonfly") {
         println!("cargo:rustc-link-lib=gcc_pic");
     } else if target.contains("pc-windows-gnu") {
diff --git a/src/tools/build-manifest/src/main.rs b/src/tools/build-manifest/src/main.rs
index f075d3e22d664..6de07d3e5cfd8 100644
--- a/src/tools/build-manifest/src/main.rs
+++ b/src/tools/build-manifest/src/main.rs
@@ -139,6 +139,7 @@ static TARGETS: &[&str] = &[
     "x86_64-pc-solaris",
     "x86_64-unknown-cloudabi",
     "x86_64-unknown-freebsd",
+    "x86_64-unknown-illumos",
     "x86_64-unknown-linux-gnu",
     "x86_64-unknown-linux-gnux32",
     "x86_64-unknown-linux-musl",
diff --git a/src/tools/compiletest/src/util.rs b/src/tools/compiletest/src/util.rs
index 2663b3d160a7a..c61bee0f8d9ea 100644
--- a/src/tools/compiletest/src/util.rs
+++ b/src/tools/compiletest/src/util.rs
@@ -21,6 +21,7 @@ const OS_TABLE: &'static [(&'static str, &'static str)] = &[
     ("fuchsia", "fuchsia"),
     ("haiku", "haiku"),
     ("hermit", "hermit"),
+    ("illumos", "illumos"),
     ("ios", "ios"),
     ("l4re", "l4re"),
     ("linux", "linux"),