diff --git a/build.rs b/build.rs
index 4edad7f740077..78ed993441d53 100644
--- a/build.rs
+++ b/build.rs
@@ -14,15 +14,10 @@ const ALLOWED_CFGS: &'static [&'static str] = &[
     "freebsd13",
     "freebsd14",
     "freebsd15",
-    "libc_cfg_target_vendor",
     "libc_const_extern_fn",
     "libc_const_extern_fn_unstable",
-    "libc_core_cvoid",
     "libc_deny_warnings",
-    "libc_int128",
     "libc_long_array",
-    "libc_non_exhaustive",
-    "libc_packedN",
     "libc_ptr_addr_of",
     "libc_thread_local",
     "libc_underscore_const_names",
@@ -54,13 +49,6 @@ fn main() {
     let libc_ci = env::var("LIBC_CI").is_ok();
     let libc_check_cfg = env::var("LIBC_CHECK_CFG").is_ok() || rustc_minor_ver >= 80;
 
-    if env::var("CARGO_FEATURE_USE_STD").is_ok() {
-        println!(
-            "cargo:warning=\"libc's use_std cargo feature is deprecated since libc 0.2.55; \
-             please consider using the `std` cargo feature instead\""
-        );
-    }
-
     // The ABI of libc used by std is backward compatible with FreeBSD 12.
     // The ABI of libc from crates.io is backward compatible with FreeBSD 11.
     //
@@ -94,29 +82,6 @@ fn main() {
         set_cfg("libc_deny_warnings");
     }
 
-    // Rust >= 1.26 supports i128 and u128:
-    if rustc_minor_ver >= 26 || rustc_dep_of_std {
-        set_cfg("libc_int128");
-    }
-
-    // Rust >= 1.30 supports `core::ffi::c_void`, so libc can just re-export it.
-    // Otherwise, it defines an incompatible type to retaining
-    // backwards-compatibility.
-    if rustc_minor_ver >= 30 || rustc_dep_of_std {
-        set_cfg("libc_core_cvoid");
-    }
-
-    // Rust >= 1.33 supports repr(packed(N)) and cfg(target_vendor).
-    if rustc_minor_ver >= 33 || rustc_dep_of_std {
-        set_cfg("libc_packedN");
-        set_cfg("libc_cfg_target_vendor");
-    }
-
-    // Rust >= 1.40 supports #[non_exhaustive].
-    if rustc_minor_ver >= 40 || rustc_dep_of_std {
-        set_cfg("libc_non_exhaustive");
-    }
-
     // Rust >= 1.47 supports long array:
     if rustc_minor_ver >= 47 || rustc_dep_of_std {
         set_cfg("libc_long_array");
diff --git a/libc-test/build.rs b/libc-test/build.rs
index 01907dff90652..0dec4bba362f5 100644
--- a/libc-test/build.rs
+++ b/libc-test/build.rs
@@ -67,7 +67,7 @@ fn do_ctest() {
 
 fn ctest_cfg() -> ctest::TestGenerator {
     let mut cfg = ctest::TestGenerator::new();
-    let libc_cfgs = ["libc_core_cvoid", "libc_packedN", "libc_thread_local"];
+    let libc_cfgs = ["libc_thread_local"];
     for f in &libc_cfgs {
         cfg.cfg(f, None);
     }
@@ -327,6 +327,9 @@ fn test_apple(target: &str) {
             // FIXME: Requires the macOS 14.4 SDK.
             "os_sync_wake_by_address_flags_t" | "os_sync_wait_on_address_flags_t" => true,
 
+            // FIXME: "'__uint128' undeclared" in C
+            "__uint128" => true,
+
             _ => false,
         }
     });
@@ -1858,6 +1861,10 @@ fn test_android(target: &str) {
             // These are intended to be opaque
             "posix_spawn_file_actions_t" => true,
             "posix_spawnattr_t" => true,
+
+            // FIXME: "'__uint128' undeclared" in C
+            "__uint128" => true,
+
             _ => false,
         }
     });
@@ -3702,6 +3709,9 @@ fn test_linux(target: &str) {
             "priority_t" if musl => true,
             "name_t" if musl => true,
 
+            // FIXME: "'__uint128' undeclared" in C
+            "__uint128" => true,
+
             t => {
                 if musl {
                     // LFS64 types have been removed in musl 1.2.4+
diff --git a/src/fixed_width_ints.rs b/src/fixed_width_ints.rs
index 999de8f54f194..980ff61ecdaf3 100644
--- a/src/fixed_width_ints.rs
+++ b/src/fixed_width_ints.rs
@@ -20,7 +20,7 @@ pub type uint32_t = u32;
 pub type uint64_t = u64;
 
 cfg_if! {
-    if #[cfg(all(libc_int128, target_arch = "aarch64", not(target_os = "windows")))] {
+    if #[cfg(all(target_arch = "aarch64", not(target_os = "windows")))] {
         // This introduces partial support for FFI with __int128 and
         // equivalent types on platforms where Rust's definition is validated
         // to match the standard C ABI of that platform.
diff --git a/src/fuchsia/mod.rs b/src/fuchsia/mod.rs
index 5495ce9549b10..9a0b8755c4659 100644
--- a/src/fuchsia/mod.rs
+++ b/src/fuchsia/mod.rs
@@ -3,6 +3,8 @@
 //! More functions and definitions can be found in the more specific modules
 //! according to the platform in question.
 
+use c_void;
+
 // PUB_TYPE
 
 pub type c_schar = i8;
@@ -4490,23 +4492,3 @@ cfg_if! {
         // Unknown target_arch
     }
 }
-
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
diff --git a/src/hermit.rs b/src/hermit.rs
index 77df54ae12d8d..8e630c38f6b65 100644
--- a/src/hermit.rs
+++ b/src/hermit.rs
@@ -1,5 +1,7 @@
 //! Hermit C type definitions
 
+use c_void;
+
 cfg_if! {
     if #[cfg(any(target_arch = "aarch64", target_arch = "riscv64"))] {
         pub type c_char = u8;
@@ -576,5 +578,3 @@ extern "C" {
     #[link_name = "sys_poll"]
     pub fn poll(fds: *mut pollfd, nfds: nfds_t, timeout: i32) -> i32;
 }
-
-pub use ffi::c_void;
diff --git a/src/lib.rs b/src/lib.rs
index ffeda95e8d505..1dba4d8248fea 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -46,9 +46,6 @@ cfg_if! {
 #[doc(hidden)]
 #[allow(unused_imports)]
 use core::clone::Clone;
-#[cfg(libc_core_cvoid)]
-#[allow(unused_imports)]
-use core::ffi;
 #[allow(unused_imports)]
 use core::fmt;
 #[allow(unused_imports)]
@@ -64,6 +61,8 @@ use core::num;
 #[allow(unused_imports)]
 use core::option::Option;
 
+pub use core::ffi::c_void;
+
 cfg_if! {
     if #[cfg(windows)] {
         mod fixed_width_ints;
diff --git a/src/psp.rs b/src/psp.rs
index a4ca029b6e0c1..3e1cdac2ceb82 100644
--- a/src/psp.rs
+++ b/src/psp.rs
@@ -4,6 +4,8 @@
 //! by the linker. Crates that use these definitions must, somewhere in the
 //! crate graph, include a stub provider crate such as the `psp` crate.
 
+use c_void;
+
 pub type c_schar = i8;
 pub type c_uchar = u8;
 pub type c_short = i16;
@@ -27,26 +29,6 @@ pub type c_char = u8;
 pub type c_long = i64;
 pub type c_ulong = u64;
 
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
-
 pub type SceKernelVTimerHandler = unsafe extern "C" fn(
     uid: SceUid,
     arg1: *mut SceKernelSysClock,
diff --git a/src/sgx.rs b/src/sgx.rs
index 7da6269399d9e..e37ccd79c3a55 100644
--- a/src/sgx.rs
+++ b/src/sgx.rs
@@ -25,23 +25,3 @@ pub type c_ulong = u64;
 
 pub const INT_MIN: c_int = -2147483648;
 pub const INT_MAX: c_int = 2147483647;
-
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
diff --git a/src/solid/mod.rs b/src/solid/mod.rs
index 2aca8d19abffd..da1ce150b0330 100644
--- a/src/solid/mod.rs
+++ b/src/solid/mod.rs
@@ -2,6 +2,8 @@
 //!
 //! [SOLID]: https://solid.kmckk.com/
 
+use c_void;
+
 pub type c_schar = i8;
 pub type c_uchar = u8;
 pub type c_short = i16;
@@ -871,26 +873,6 @@ extern "C" {
     pub fn lseek(arg1: c_int, arg2: __off_t, arg3: c_int) -> __off_t;
 }
 
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
-
 cfg_if! {
     if #[cfg(target_arch = "aarch64")] {
         mod aarch64;
diff --git a/src/switch.rs b/src/switch.rs
index 030ab20d7bd8e..4a8b16e15f568 100644
--- a/src/switch.rs
+++ b/src/switch.rs
@@ -27,23 +27,3 @@ pub type wchar_t = u32;
 
 pub const INT_MIN: c_int = -2147483648;
 pub const INT_MAX: c_int = 2147483647;
-
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
diff --git a/src/unix/bsd/apple/b64/aarch64/mod.rs b/src/unix/bsd/apple/b64/aarch64/mod.rs
index 1d4a5590fbf36..dd22fcb2507b1 100644
--- a/src/unix/bsd/apple/b64/aarch64/mod.rs
+++ b/src/unix/bsd/apple/b64/aarch64/mod.rs
@@ -37,16 +37,8 @@ s! {
         pub __pad: u32,
     }
 
-    // This type natively uses a uint128, but for a while we hacked
-    // it in with repr(align) and `[u64; 2]`. uint128 isn't available
-    // all the way back to our earliest supported versions so we
-    // preserver the old shim.
-    #[cfg_attr(not(libc_int128), repr(align(16)))]
     pub struct __darwin_arm_neon_state64 {
-        #[cfg(libc_int128)]
         pub __v: [::__uint128_t; 32],
-        #[cfg(not(libc_int128))]
-        pub __v: [[u64; 2]; 32],
         pub __fpsr: u32,
         pub __fpcr: u32,
     }
diff --git a/src/unix/bsd/apple/mod.rs b/src/unix/bsd/apple/mod.rs
index efac489dcfc30..7ed887753c971 100644
--- a/src/unix/bsd/apple/mod.rs
+++ b/src/unix/bsd/apple/mod.rs
@@ -1193,13 +1193,13 @@ s! {
 }
 
 s_no_extra_traits! {
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct ifconf {
         pub ifc_len: ::c_int,
         pub ifc_ifcu: __c_anonymous_ifc_ifcu,
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct kevent {
         pub ident: ::uintptr_t,
         pub filter: i16,
@@ -1209,7 +1209,7 @@ s_no_extra_traits! {
         pub udata: *mut ::c_void,
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct semid_ds {
         // Note the manpage shows different types than the system header.
         pub sem_perm: ipc_perm,
@@ -1222,7 +1222,7 @@ s_no_extra_traits! {
         pub sem_pad3: [i32; 4],
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct shmid_ds {
         pub shm_perm: ipc_perm,
         pub shm_segsz: ::size_t,
@@ -1381,7 +1381,7 @@ s_no_extra_traits! {
         pub pth_name: [::c_char; MAXTHREADNAMESIZE],
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct if_data64 {
         pub ifi_type: ::c_uchar,
         pub ifi_typelen: ::c_uchar,
@@ -1413,7 +1413,7 @@ s_no_extra_traits! {
         pub ifi_lastchange: timeval32,
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct if_msghdr2 {
         pub ifm_msglen: ::c_ushort,
         pub ifm_version: ::c_uchar,
@@ -1428,7 +1428,7 @@ s_no_extra_traits! {
         pub ifm_data: if_data64,
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(8)))]
+    #[repr(packed(8))]
     pub struct vm_statistics64 {
         pub free_count: natural_t,
         pub active_count: natural_t,
@@ -1456,7 +1456,7 @@ s_no_extra_traits! {
         pub total_uncompressed_pages_in_compressor: u64,
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct mach_task_basic_info {
         pub virtual_size: mach_vm_size_t,
         pub resident_size: mach_vm_size_t,
@@ -1467,7 +1467,7 @@ s_no_extra_traits! {
         pub suspend_count: integer_t,
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct log2phys {
         pub l2p_flags: ::c_uint,
         pub l2p_contigbytes: ::off_t,
@@ -1478,7 +1478,7 @@ s_no_extra_traits! {
         _os_unfair_lock_opaque: u32,
     }
 
-   #[cfg_attr(libc_packedN, repr(packed(1)))]
+   #[repr(packed(1))]
     pub struct sockaddr_vm {
         pub svm_len: ::c_uchar,
         pub svm_family: ::sa_family_t,
@@ -1498,7 +1498,7 @@ s_no_extra_traits! {
         pub ifk_value: ::c_int,
     }
 
-    #[cfg_attr(libc_packedN, repr(packed(4)))]
+    #[repr(packed(4))]
     pub struct ifkpi {
         pub ifk_module_id: ::c_uint,
         pub ifk_type: ::c_uint,
diff --git a/src/unix/linux_like/android/b64/aarch64/int128.rs b/src/unix/linux_like/android/b64/aarch64/int128.rs
deleted file mode 100644
index 4535e73eeddf1..0000000000000
--- a/src/unix/linux_like/android/b64/aarch64/int128.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-s! {
-    pub struct user_fpsimd_struct {
-        pub vregs: [::__uint128_t; 32],
-        pub fpsr: u32,
-        pub fpcr: u32,
-    }
-}
diff --git a/src/unix/linux_like/android/b64/aarch64/mod.rs b/src/unix/linux_like/android/b64/aarch64/mod.rs
index d063c022bfb7e..49b990fd8f1ac 100644
--- a/src/unix/linux_like/android/b64/aarch64/mod.rs
+++ b/src/unix/linux_like/android/b64/aarch64/mod.rs
@@ -75,6 +75,12 @@ s! {
         // auto-derive traits like Debug
         __reserved: [[u64; 32]; 16],
     }
+
+    pub struct user_fpsimd_struct {
+        pub vregs: [::__uint128_t; 32],
+        pub fpsr: u32,
+        pub fpcr: u32,
+    }
 }
 
 s_no_extra_traits! {
@@ -448,10 +454,3 @@ pub const PROT_MTE: ::c_int = 0x20;
 // From NDK's asm/auxvec.h
 pub const AT_SYSINFO_EHDR: ::c_ulong = 33;
 pub const AT_VECTOR_SIZE_ARCH: ::c_ulong = 2;
-
-cfg_if! {
-    if #[cfg(libc_int128)] {
-        mod int128;
-        pub use self::int128::*;
-    }
-}
diff --git a/src/unix/linux_like/linux/gnu/b64/aarch64/fallback.rs b/src/unix/linux_like/linux/gnu/b64/aarch64/fallback.rs
deleted file mode 100644
index 398fbb53755c8..0000000000000
--- a/src/unix/linux_like/linux/gnu/b64/aarch64/fallback.rs
+++ /dev/null
@@ -1,8 +0,0 @@
-s! {
-    #[repr(align(16))]
-    pub struct user_fpsimd_struct {
-        pub vregs: [[u64; 2]; 32],
-        pub fpsr: ::c_uint,
-        pub fpcr: ::c_uint,
-    }
-}
diff --git a/src/unix/linux_like/linux/gnu/b64/aarch64/int128.rs b/src/unix/linux_like/linux/gnu/b64/aarch64/int128.rs
deleted file mode 100644
index 4535e73eeddf1..0000000000000
--- a/src/unix/linux_like/linux/gnu/b64/aarch64/int128.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-s! {
-    pub struct user_fpsimd_struct {
-        pub vregs: [::__uint128_t; 32],
-        pub fpsr: u32,
-        pub fpcr: u32,
-    }
-}
diff --git a/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs b/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
index 783200a6d6e9c..5ee559190a8a2 100644
--- a/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
+++ b/src/unix/linux_like/linux/gnu/b64/aarch64/mod.rs
@@ -217,6 +217,12 @@ s! {
         __reserved: [[u64; 32]; 16],
     }
 
+    pub struct user_fpsimd_struct {
+        pub vregs: [::__uint128_t; 32],
+        pub fpsr: ::c_uint,
+        pub fpcr: ::c_uint,
+    }
+
     #[repr(align(8))]
     pub struct clone_args {
         pub flags: ::c_ulonglong,
@@ -964,13 +970,3 @@ cfg_if! {
         pub use self::lp64::*;
     }
 }
-
-cfg_if! {
-    if #[cfg(libc_int128)] {
-        mod int128;
-        pub use self::int128::*;
-    } else {
-        mod fallback;
-        pub use self::fallback::*;
-    }
-}
diff --git a/src/unix/linux_like/linux/mod.rs b/src/unix/linux_like/linux/mod.rs
index 28d29251769ca..5629fe0d0a608 100644
--- a/src/unix/linux_like/linux/mod.rs
+++ b/src/unix/linux_like/linux/mod.rs
@@ -953,6 +953,14 @@ s! {
         pub pid: ::c_int,
     }
 
+    // linux/openat2.h
+    #[non_exhaustive]
+    pub struct open_how {
+        pub flags: ::__u64,
+        pub mode: ::__u64,
+        pub resolve: ::__u64,
+    }
+
     #[repr(align(8))]
     pub struct tpacket_rollover_stats {
         pub tp_all: ::__u64,
@@ -6183,10 +6191,3 @@ cfg_if! {
 
 mod arch;
 pub use self::arch::*;
-
-cfg_if! {
-    if #[cfg(libc_non_exhaustive)] {
-        mod non_exhaustive;
-        pub use self::non_exhaustive::*;
-    }
-}
diff --git a/src/unix/linux_like/linux/musl/b64/aarch64/int128.rs b/src/unix/linux_like/linux/musl/b64/aarch64/int128.rs
deleted file mode 100644
index 4535e73eeddf1..0000000000000
--- a/src/unix/linux_like/linux/musl/b64/aarch64/int128.rs
+++ /dev/null
@@ -1,7 +0,0 @@
-s! {
-    pub struct user_fpsimd_struct {
-        pub vregs: [::__uint128_t; 32],
-        pub fpsr: u32,
-        pub fpcr: u32,
-    }
-}
diff --git a/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs b/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs
index 7582676c3bfa6..f71d47effe85c 100644
--- a/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs
+++ b/src/unix/linux_like/linux/musl/b64/aarch64/mod.rs
@@ -101,6 +101,12 @@ s! {
         pub set_tid_size: ::c_ulonglong,
         pub cgroup: ::c_ulonglong,
     }
+
+    pub struct user_fpsimd_struct {
+        pub vregs: [::__uint128_t; 32],
+        pub fpsr: u32,
+        pub fpcr: u32,
+    }
 }
 
 s_no_extra_traits! {
@@ -684,10 +690,3 @@ pub const VMIN: usize = 6;
 pub const IEXTEN: ::tcflag_t = 0x00008000;
 pub const TOSTOP: ::tcflag_t = 0x00000100;
 pub const FLUSHO: ::tcflag_t = 0x00001000;
-
-cfg_if! {
-    if #[cfg(libc_int128)] {
-        mod int128;
-        pub use self::int128::*;
-    }
-}
diff --git a/src/unix/linux_like/linux/non_exhaustive.rs b/src/unix/linux_like/linux/non_exhaustive.rs
deleted file mode 100644
index e2e2cb847ac65..0000000000000
--- a/src/unix/linux_like/linux/non_exhaustive.rs
+++ /dev/null
@@ -1,9 +0,0 @@
-s! {
-    // linux/openat2.h
-    #[non_exhaustive]
-    pub struct open_how {
-        pub flags: ::__u64,
-        pub mode: ::__u64,
-        pub resolve: ::__u64,
-    }
-}
diff --git a/src/unix/mod.rs b/src/unix/mod.rs
index 1556c12726eb0..b3cc7424cd0d4 100644
--- a/src/unix/mod.rs
+++ b/src/unix/mod.rs
@@ -3,6 +3,8 @@
 //! More functions and definitions can be found in the more specific modules
 //! according to the platform in question.
 
+use c_void;
+
 pub type c_schar = i8;
 pub type c_uchar = u8;
 pub type c_short = i16;
@@ -640,21 +642,13 @@ extern "C" {
     pub fn getchar_unlocked() -> ::c_int;
     pub fn putchar_unlocked(c: ::c_int) -> ::c_int;
 
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(target_os = "netbsd", link_name = "__socket30")]
     #[cfg_attr(target_os = "illumos", link_name = "__xnet_socket")]
     #[cfg_attr(target_os = "solaris", link_name = "__xnet7_socket")]
     #[cfg_attr(target_os = "espidf", link_name = "lwip_socket")]
     pub fn socket(domain: ::c_int, ty: ::c_int, protocol: ::c_int) -> ::c_int;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(
         all(target_os = "macos", target_arch = "x86"),
         link_name = "connect$UNIX2003"
@@ -671,22 +665,14 @@ extern "C" {
     )]
     #[cfg_attr(target_os = "espidf", link_name = "lwip_listen")]
     pub fn listen(socket: ::c_int, backlog: ::c_int) -> ::c_int;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(
         all(target_os = "macos", target_arch = "x86"),
         link_name = "accept$UNIX2003"
     )]
     #[cfg_attr(target_os = "espidf", link_name = "lwip_accept")]
     pub fn accept(socket: ::c_int, address: *mut sockaddr, address_len: *mut socklen_t) -> ::c_int;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(
         all(target_os = "macos", target_arch = "x86"),
         link_name = "getpeername$UNIX2003"
@@ -697,11 +683,7 @@ extern "C" {
         address: *mut sockaddr,
         address_len: *mut socklen_t,
     ) -> ::c_int;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(
         all(target_os = "macos", target_arch = "x86"),
         link_name = "getsockname$UNIX2003"
@@ -734,11 +716,7 @@ extern "C" {
         protocol: ::c_int,
         socket_vector: *mut ::c_int,
     ) -> ::c_int;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(
         all(target_os = "macos", target_arch = "x86"),
         link_name = "sendto$UNIX2003"
@@ -1248,11 +1226,7 @@ extern "C" {
     pub fn dlsym(handle: *mut ::c_void, symbol: *const ::c_char) -> *mut ::c_void;
     pub fn dlclose(handle: *mut ::c_void) -> ::c_int;
 
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(
         any(target_os = "illumos", target_os = "solaris"),
         link_name = "__xnet_getaddrinfo"
@@ -1264,11 +1238,7 @@ extern "C" {
         hints: *const addrinfo,
         res: *mut *mut addrinfo,
     ) -> ::c_int;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(target_os = "espidf", link_name = "lwip_freeaddrinfo")]
     pub fn freeaddrinfo(res: *mut addrinfo);
     pub fn hstrerror(errcode: ::c_int) -> *const ::c_char;
@@ -1703,23 +1673,3 @@ cfg_if! {
         // Unknown target_os
     }
 }
-
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
diff --git a/src/unix/newlib/mod.rs b/src/unix/newlib/mod.rs
index e68da50aa3c0a..45d1b1a028fad 100644
--- a/src/unix/newlib/mod.rs
+++ b/src/unix/newlib/mod.rs
@@ -91,7 +91,7 @@ s! {
 
         #[cfg(not(any(
             target_os = "espidf",
-            all(libc_cfg_target_vendor, target_arch = "powerpc", target_vendor = "nintendo"))))]
+            all(target_arch = "powerpc", target_vendor = "nintendo"))))]
         pub ai_addr: *mut sockaddr,
 
         pub ai_next: *mut addrinfo,
@@ -843,11 +843,7 @@ extern "C" {
     pub fn rand() -> ::c_int;
     pub fn srand(seed: ::c_uint);
 
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(target_os = "espidf", link_name = "lwip_bind")]
     pub fn bind(fd: ::c_int, addr: *const sockaddr, len: socklen_t) -> ::c_int;
     pub fn clock_settime(clock_id: ::clockid_t, tp: *const ::timespec) -> ::c_int;
@@ -856,11 +852,7 @@ extern "C" {
     #[cfg_attr(target_os = "espidf", link_name = "lwip_close")]
     pub fn closesocket(sockfd: ::c_int) -> ::c_int;
     pub fn ioctl(fd: ::c_int, request: ::c_ulong, ...) -> ::c_int;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     #[cfg_attr(target_os = "espidf", link_name = "lwip_recvfrom")]
     pub fn recvfrom(
         fd: ::c_int,
@@ -870,11 +862,7 @@ extern "C" {
         addr: *mut sockaddr,
         addr_len: *mut socklen_t,
     ) -> isize;
-    #[cfg(not(all(
-        libc_cfg_target_vendor,
-        target_arch = "powerpc",
-        target_vendor = "nintendo"
-    )))]
+    #[cfg(not(all(target_arch = "powerpc", target_vendor = "nintendo")))]
     pub fn getnameinfo(
         sa: *const sockaddr,
         salen: socklen_t,
diff --git a/src/unix/solarish/illumos.rs b/src/unix/solarish/illumos.rs
index 62a07f6279030..07cc583f43f3d 100644
--- a/src/unix/solarish/illumos.rs
+++ b/src/unix/solarish/illumos.rs
@@ -46,10 +46,7 @@ s! {
 }
 
 s_no_extra_traits! {
-    #[cfg_attr(any(
-        target_arch = "x86", target_arch = "x86_64"),
-        repr(packed(4))
-    )]
+    #[cfg_attr(any(target_arch = "x86", target_arch = "x86_64"), repr(packed(4)))]
     pub struct epoll_event {
         pub events: u32,
         pub u64: u64,
diff --git a/src/vxworks/mod.rs b/src/vxworks/mod.rs
index daf3b013b48b3..18b102b906767 100644
--- a/src/vxworks/mod.rs
+++ b/src/vxworks/mod.rs
@@ -1,5 +1,6 @@
 //! Interface to VxWorks C library
 
+use c_void;
 use core::mem::size_of;
 use core::ptr::null_mut;
 
@@ -2003,26 +2004,6 @@ pub fn posix_memalign(memptr: *mut *mut ::c_void, align: ::size_t, size: ::size_
     }
 }
 
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
-
 cfg_if! {
     if #[cfg(target_arch = "aarch64")] {
         mod aarch64;
diff --git a/src/wasi/mod.rs b/src/wasi/mod.rs
index 743f607379768..b157ab0d59b04 100644
--- a/src/wasi/mod.rs
+++ b/src/wasi/mod.rs
@@ -1,7 +1,7 @@
-use super::{Send, Sync};
 use core::iter::Iterator;
 
-pub use ffi::c_void;
+use super::{Send, Sync};
+use c_void;
 
 pub type c_char = i8;
 pub type c_uchar = u8;
diff --git a/src/windows/mod.rs b/src/windows/mod.rs
index 63536a809a421..2270e7078c966 100644
--- a/src/windows/mod.rs
+++ b/src/windows/mod.rs
@@ -1,5 +1,7 @@
 //! Windows CRT definitions
 
+use c_void;
+
 pub type c_schar = i8;
 pub type c_uchar = u8;
 pub type c_short = i16;
@@ -568,26 +570,6 @@ extern "system" {
     pub fn socket(af: ::c_int, socket_type: ::c_int, protocol: ::c_int) -> SOCKET;
 }
 
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}
-
 cfg_if! {
     if #[cfg(all(target_env = "gnu"))] {
         mod gnu;
diff --git a/src/xous.rs b/src/xous.rs
index e6c0c2573d07d..4073349306fb9 100644
--- a/src/xous.rs
+++ b/src/xous.rs
@@ -27,23 +27,3 @@ pub type wchar_t = u32;
 
 pub const INT_MIN: c_int = -2147483648;
 pub const INT_MAX: c_int = 2147483647;
-
-cfg_if! {
-    if #[cfg(libc_core_cvoid)] {
-        pub use ::ffi::c_void;
-    } else {
-        // Use repr(u8) as LLVM expects `void*` to be the same as `i8*` to help
-        // enable more optimization opportunities around it recognizing things
-        // like malloc/free.
-        #[repr(u8)]
-        #[allow(missing_copy_implementations)]
-        #[allow(missing_debug_implementations)]
-        pub enum c_void {
-            // Two dummy variants so the #[repr] attribute can be used.
-            #[doc(hidden)]
-            __variant1,
-            #[doc(hidden)]
-            __variant2,
-        }
-    }
-}