diff --git a/ci/build.sh b/ci/build.sh
index 69805fcbc281d5875ef4a371774fb924f0198303..09a05be121c8b6eca935db2b9d836e2a4c3c5338 100644
--- a/ci/build.sh
+++ b/ci/build.sh
@@ -11,7 +11,8 @@ OS=${TRAVIS_OS_NAME}
 echo "Testing Rust ${RUST} on ${OS}"
 
 test_target() {
-    TARGET="${1}"
+    CARGO="${1}"
+    TARGET="${2}"
 
     opt=
     if [ "${TARGET}" = "x86_64-unknown-linux-gnux32" ]; then
@@ -22,7 +23,7 @@ test_target() {
         opt="--release"
     fi
 
-    NO_STD=
+    NO_STD="${3}"
     case ${TARGET} in
         thumbv*)
             NO_STD=1
@@ -32,25 +33,62 @@ test_target() {
     rustup target add "${TARGET}" --toolchain "${RUST}" || true
 
     # Test that libc builds without any default features (no libstd)
-    cargo "+${RUST}" build -vv $opt --no-default-features --target "${TARGET}"
+    "$CARGO" "+${RUST}" build -vv $opt --no-default-features --target "${TARGET}"
 
     # Test that libc builds with default features (e.g. libstd)
     # if the target supports libstd
     if [ "$NO_STD" != "1" ]; then
-        cargo "+${RUST}" build -vv $opt --target "${TARGET}"
+        "$CARGO" "+${RUST}" build -vv $opt --target "${TARGET}"
     fi
 
     # Test that libc builds with the `extra_traits` feature
-    cargo "+${RUST}" build -vv $opt --no-default-features --target "${TARGET}" \
+    "$CARGO" "+${RUST}" build -vv $opt --no-default-features --target "${TARGET}" \
           --features extra_traits
 
     # Also test that it builds with `extra_traits` and default features:
     if [ "$NO_STD" != "1" ]; then
-        cargo "+${RUST}" build -vv $opt --target "${TARGET}" \
+        "$CARGO" "+${RUST}" build -vv $opt --target "${TARGET}" \
               --features extra_traits
     fi
 }
 
+rustup component add rust-src || true
+cargo install xargo || true
+
+
+RUST_LINUX_NO_CORE_TARGETS="\
+x86_64-unknown-dragonfly \
+aarch64-pc-windows-msvc \
+aarch64-unknown-cloudabi \
+armv7-unknown-cloudabi-eabihf \
+i586-pc-windows-msvc \
+i686-pc-windows-gnu \
+i686-pc-windows-msvc \
+i686-unknown-cloudabi \
+i686-unknown-haiku \
+i686-unknown-netbsd \
+mips-unknown-linux-uclib \
+mipsel-unknown-unknown-linux-uclib \
+nvptx64-nvidia-cuda \
+powerpc-unknown-linux-gnuspe \
+riscv32imac-unknown-none-elf \
+riscv32imc-unknown-none-elf \
+sparc-unknown-linux-gnu \
+sparc64-unknown-netbsd \
+thumbv8m.main-none-eabi \
+x86_64-pc-windows-gnu \
+x86_64-pc-windows-msvc
+x86_64-unknown-bitrig \
+x86_64-unknown-haiku \
+x86_64-unknown-openbsd
+"
+
+for TARGET in $RUST_LINUX_NO_CORE_TARGETS; do
+    if [ "${RUST}" = "nightly" ]; then
+        RUST_LIBC_NO_CORE_BUILD=1 test_target xargo "$TARGET" 1
+    fi
+done
+
 RUST_LINUX_TARGETS="\
 aarch64-linux-android \
 aarch64-unknown-linux-gnu \
@@ -103,6 +141,12 @@ x86_64-unknown-cloudabi \
 
 RUST_NIGHTLY_LINUX_TARGETS="\
 aarch64-fuchsia \
+armv5te-unknown-linux-gnueabi \
+armv5te-unknown-linux-musleabi \
+armebv7r-none-eabi \
+armebv7r-none-eabihf \
+armv7r-none-eabi \
+armv7r-none-eabihf \
 thumbv6m-none-eabi \
 thumbv7em-none-eabi \
 thumbv7em-none-eabihf \
@@ -161,5 +205,5 @@ case "${OS}" in
 esac
 
 for TARGET in $TARGETS; do
-    test_target "$TARGET"
+    test_target cargo "$TARGET"
 done
diff --git a/src/dox.rs b/src/dox.rs
deleted file mode 100644
index d9899bb2249d38df8142a4ab1b239bbd8dc24753..0000000000000000000000000000000000000000
--- a/src/dox.rs
+++ /dev/null
@@ -1,211 +0,0 @@
-pub enum Option<T> {
-    Some(T),
-    None,
-}
-impl<T: Copy> Copy for Option<T> {}
-impl<T: Clone> Clone for Option<T> {
-    fn clone(&self) -> Option<T> {
-        loop {}
-    }
-}
-
-impl<T> Copy for *mut T {}
-impl<T> Clone for *mut T {
-    fn clone(&self) -> *mut T {
-        loop {}
-    }
-}
-
-impl<T> Copy for *const T {}
-impl<T> Clone for *const T {
-    fn clone(&self) -> *const T {
-        loop {}
-    }
-}
-
-pub trait Clone {
-    fn clone(&self) -> Self;
-}
-
-#[lang = "copy"]
-pub trait Copy {}
-
-#[lang = "freeze"]
-pub trait Freeze {}
-
-#[lang = "sync"]
-pub trait Sync {}
-impl<T> Sync for T {}
-
-#[lang = "sized"]
-pub trait Sized {}
-
-#[lang = "receiver"]
-pub trait Receiver {}
-impl<T: ?Sized> Receiver for &T {}
-impl<T: ?Sized> Receiver for &mut T {}
-
-macro_rules! each_int {
-    ($mac:ident) => {
-        $mac!(u8);
-        $mac!(u16);
-        $mac!(u32);
-        $mac!(u64);
-        $mac!(usize);
-        each_signed_int!($mac);
-    };
-}
-
-macro_rules! each_signed_int {
-    ($mac:ident) => {
-        $mac!(i8);
-        $mac!(i16);
-        $mac!(i32);
-        $mac!(i64);
-        $mac!(isize);
-    };
-}
-
-#[lang = "div"]
-pub trait Div<RHS = Self> {
-    type Output;
-    fn div(self, rhs: RHS) -> Self::Output;
-}
-
-#[lang = "shl"]
-pub trait Shl<RHS = Self> {
-    type Output;
-    fn shl(self, rhs: RHS) -> Self::Output;
-}
-
-#[lang = "mul"]
-pub trait Mul<RHS = Self> {
-    type Output;
-    fn mul(self, rhs: RHS) -> Self::Output;
-}
-
-#[lang = "sub"]
-pub trait Sub<RHS = Self> {
-    type Output;
-    fn sub(self, rhs: RHS) -> Self::Output;
-}
-
-#[lang = "bitand"]
-pub trait BitAnd<RHS = Self> {
-    type Output;
-    fn bitand(self, rhs: RHS) -> Self::Output;
-}
-
-#[lang = "bitand_assign"]
-pub trait BitAndAssign<RHS = Self> {
-    fn bitand_assign(&mut self, rhs: RHS);
-}
-
-#[lang = "bitor"]
-pub trait BitOr<RHS = Self> {
-    type Output;
-    fn bitor(self, rhs: RHS) -> Self::Output;
-}
-
-#[lang = "bitor_assign"]
-pub trait BitOrAssign<RHS = Self> {
-    fn bitor_assign(&mut self, rhs: RHS);
-}
-
-#[lang = "bitxor"]
-pub trait BitXor<RHS = Self> {
-    type Output;
-    fn bitxor(self, rhs: RHS) -> Self::Output;
-}
-
-#[lang = "bitxor_assign"]
-pub trait BitXorAssign<RHS = Self> {
-    fn bitxor_assign(&mut self, rhs: RHS);
-}
-
-#[lang = "neg"]
-pub trait Neg {
-    type Output;
-    fn neg(self) -> Self::Output;
-}
-
-#[lang = "not"]
-pub trait Not {
-    type Output;
-    fn not(self) -> Self::Output;
-}
-
-#[lang = "add"]
-pub trait Add<RHS = Self> {
-    type Output;
-    fn add(self, r: RHS) -> Self::Output;
-}
-
-macro_rules! impl_traits {
-    ($($i:ident)*) => ($(
-        impl Div<$i> for $i {
-            type Output = $i;
-            fn div(self, rhs: $i) -> $i { self / rhs }
-        }
-        impl Shl<$i> for $i {
-            type Output = $i;
-            fn shl(self, rhs: $i) -> $i { self << rhs }
-        }
-        impl Mul for $i {
-            type Output = $i;
-            fn mul(self, rhs: $i) -> $i { self * rhs }
-        }
-
-        impl Sub for $i {
-            type Output = $i;
-            fn sub(self, rhs: $i) -> $i { self - rhs }
-        }
-        impl BitAnd for $i {
-            type Output = $i;
-            fn bitand(self, rhs: $i) -> $i { self & rhs }
-        }
-        impl BitAndAssign for $i {
-            fn bitand_assign(&mut self, rhs: $i) { *self &= rhs; }
-        }
-        impl BitOr for $i {
-            type Output = $i;
-            fn bitor(self, rhs: $i) -> $i { self | rhs }
-        }
-        impl BitOrAssign for $i {
-            fn bitor_assign(&mut self, rhs: $i) { *self |= rhs; }
-        }
-        impl BitXor for $i {
-            type Output = $i;
-            fn bitxor(self, rhs: $i) -> $i { self ^ rhs }
-        }
-        impl BitXorAssign for $i {
-            fn bitxor_assign(&mut self, rhs: $i) { *self ^= rhs; }
-        }
-        impl Neg for $i {
-            type Output = $i;
-            fn neg(self) -> $i { -self }
-        }
-        impl Not for $i {
-            type Output = $i;
-            fn not(self) -> $i { !self }
-        }
-        impl Add<$i> for $i {
-            type Output = $i;
-            fn add(self, other: $i) -> $i { self + other }
-        }
-        impl Copy for $i {}
-        impl Clone for $i {
-            fn clone(&self) -> $i { loop {} }
-        }
-    )*)
-}
-each_int!(impl_traits);
-
-pub mod mem {
-    pub fn size_of_val<T>(_: &T) -> usize {
-        4
-    }
-    pub const fn size_of<T>() -> usize {
-        4
-    }
-}
diff --git a/src/lib.rs b/src/lib.rs
index 8a7750acb0acac2090146b922fdefbee6c97d9be..b1afc08a01afa9fa26d27a6961aeb3a6bc23d8fb 100644
--- a/src/lib.rs
+++ b/src/lib.rs
@@ -8,13 +8,10 @@
 // option. This file may not be copied, modified, or distributed
 // except according to those terms.
 //! libc - Raw FFI bindings to platforms' system libraries
-
 #![crate_name = "libc"]
 #![crate_type = "rlib"]
 #![cfg_attr(not(feature = "rustc-dep-of-std"), deny(warnings))]
 #![allow(bad_style, overflowing_literals, improper_ctypes, unknown_lints)]
-#![cfg_attr(cross_platform_docs, feature(no_core, lang_items, const_fn))]
-#![cfg_attr(cross_platform_docs, no_core)]
 // Attributes needed when building as part of the standard library
 #![cfg_attr(
     feature = "rustc-dep-of-std",
@@ -28,7 +25,7 @@
     not(any(
         feature = "use_std",
         feature = "rustc-dep-of-std",
-        cross_platform_docs
+        cross_platform_docs,
     )),
     no_std
 )]
@@ -50,60 +47,49 @@ cfg_if! {
 }
 
 cfg_if! {
-    if #[cfg(not(cross_platform_docs))] {
-        cfg_if! {
-            if #[cfg(libc_priv_mod_use)] {
-                #[cfg(libc_core_cvoid)]
-                #[allow(unused_imports)]
-                use core::ffi;
-                #[allow(unused_imports)]
-                use core::fmt;
-                #[allow(unused_imports)]
-                use core::hash;
-                #[allow(unused_imports)]
-                use core::num;
-                #[allow(unused_imports)]
-                use core::mem;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::clone::Clone;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::marker::Copy;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::option::Option;
-            } else {
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::fmt;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::hash;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::num;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::mem;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::clone::Clone;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::marker::Copy;
-                #[doc(hidden)]
-                #[allow(unused_imports)]
-                pub use core::option::Option;
-            }
-        }
-    }
-}
-
-cfg_if! {
-    if #[cfg(cross_platform_docs)] {
-        mod dox;
-        pub use self::dox::*;
+    if #[cfg(libc_priv_mod_use)] {
+        #[cfg(libc_core_cvoid)]
+        #[allow(unused_imports)]
+        use core::ffi;
+        #[allow(unused_imports)]
+        use core::fmt;
+        #[allow(unused_imports)]
+        use core::hash;
+        #[allow(unused_imports)]
+        use core::num;
+        #[allow(unused_imports)]
+        use core::mem;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::clone::Clone;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::marker::Copy;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::option::Option;
+    } else {
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::fmt;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::hash;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::num;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::mem;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::clone::Clone;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::marker::Copy;
+        #[doc(hidden)]
+        #[allow(unused_imports)]
+        pub use core::option::Option;
     }
 }