diff --git a/library/std/src/sys/hermit/cmath.rs b/library/std/src/sys/hermit/cmath.rs
deleted file mode 100644
index 304cf906b2a..00000000000
--- a/library/std/src/sys/hermit/cmath.rs
+++ /dev/null
@@ -1,29 +0,0 @@
-// These symbols are all defined in `compiler-builtins`
-extern "C" {
-    pub fn acos(n: f64) -> f64;
-    pub fn acosf(n: f32) -> f32;
-    pub fn asin(n: f64) -> f64;
-    pub fn asinf(n: f32) -> f32;
-    pub fn atan(n: f64) -> f64;
-    pub fn atan2(a: f64, b: f64) -> f64;
-    pub fn atan2f(a: f32, b: f32) -> f32;
-    pub fn atanf(n: f32) -> f32;
-    pub fn cbrt(n: f64) -> f64;
-    pub fn cbrtf(n: f32) -> f32;
-    pub fn cosh(n: f64) -> f64;
-    pub fn coshf(n: f32) -> f32;
-    pub fn expm1(n: f64) -> f64;
-    pub fn expm1f(n: f32) -> f32;
-    pub fn fdim(a: f64, b: f64) -> f64;
-    pub fn fdimf(a: f32, b: f32) -> f32;
-    pub fn hypot(x: f64, y: f64) -> f64;
-    pub fn hypotf(x: f32, y: f32) -> f32;
-    pub fn log1p(n: f64) -> f64;
-    pub fn log1pf(n: f32) -> f32;
-    pub fn sinh(n: f64) -> f64;
-    pub fn sinhf(n: f32) -> f32;
-    pub fn tan(n: f64) -> f64;
-    pub fn tanf(n: f32) -> f32;
-    pub fn tanh(n: f64) -> f64;
-    pub fn tanhf(n: f32) -> f32;
-}
diff --git a/library/std/src/sys/hermit/mod.rs b/library/std/src/sys/hermit/mod.rs
index 3364d215776..0c49a6fb6de 100644
--- a/library/std/src/sys/hermit/mod.rs
+++ b/library/std/src/sys/hermit/mod.rs
@@ -20,6 +20,7 @@ use crate::os::raw::c_char;
 
 pub mod alloc;
 pub mod args;
+#[path = "../unix/cmath.rs"]
 pub mod cmath;
 pub mod condvar;
 pub mod env;
diff --git a/library/std/src/sys/sgx/cmath.rs b/library/std/src/sys/sgx/cmath.rs
deleted file mode 100644
index b89238f1da8..00000000000
--- a/library/std/src/sys/sgx/cmath.rs
+++ /dev/null
@@ -1,31 +0,0 @@
-#![cfg(not(test))]
-
-// These symbols are all defined in `compiler-builtins`
-extern "C" {
-    pub fn acos(n: f64) -> f64;
-    pub fn acosf(n: f32) -> f32;
-    pub fn asin(n: f64) -> f64;
-    pub fn asinf(n: f32) -> f32;
-    pub fn atan(n: f64) -> f64;
-    pub fn atan2(a: f64, b: f64) -> f64;
-    pub fn atan2f(a: f32, b: f32) -> f32;
-    pub fn atanf(n: f32) -> f32;
-    pub fn cbrt(n: f64) -> f64;
-    pub fn cbrtf(n: f32) -> f32;
-    pub fn cosh(n: f64) -> f64;
-    pub fn coshf(n: f32) -> f32;
-    pub fn expm1(n: f64) -> f64;
-    pub fn expm1f(n: f32) -> f32;
-    pub fn fdim(a: f64, b: f64) -> f64;
-    pub fn fdimf(a: f32, b: f32) -> f32;
-    pub fn hypot(x: f64, y: f64) -> f64;
-    pub fn hypotf(x: f32, y: f32) -> f32;
-    pub fn log1p(n: f64) -> f64;
-    pub fn log1pf(n: f32) -> f32;
-    pub fn sinh(n: f64) -> f64;
-    pub fn sinhf(n: f32) -> f32;
-    pub fn tan(n: f64) -> f64;
-    pub fn tanf(n: f32) -> f32;
-    pub fn tanh(n: f64) -> f64;
-    pub fn tanhf(n: f32) -> f32;
-}
diff --git a/library/std/src/sys/sgx/mod.rs b/library/std/src/sys/sgx/mod.rs
index 059d6cb5ba1..bf3bd57e982 100644
--- a/library/std/src/sys/sgx/mod.rs
+++ b/library/std/src/sys/sgx/mod.rs
@@ -13,6 +13,7 @@ mod waitqueue;
 
 pub mod alloc;
 pub mod args;
+#[path = "../unix/cmath.rs"]
 pub mod cmath;
 pub mod condvar;
 pub mod env;
diff --git a/library/std/src/sys/unix/cmath.rs b/library/std/src/sys/unix/cmath.rs
index f327b69fc75..2bf80d7a4cb 100644
--- a/library/std/src/sys/unix/cmath.rs
+++ b/library/std/src/sys/unix/cmath.rs
@@ -1,32 +1,33 @@
 #![cfg(not(test))]
 
-use libc::{c_double, c_float};
+// These symbols are all defined by `libm`,
+// or by `compiler-builtins` on unsupported platforms.
 
 extern "C" {
-    pub fn acos(n: c_double) -> c_double;
-    pub fn acosf(n: c_float) -> c_float;
-    pub fn asin(n: c_double) -> c_double;
-    pub fn asinf(n: c_float) -> c_float;
-    pub fn atan(n: c_double) -> c_double;
-    pub fn atan2(a: c_double, b: c_double) -> c_double;
-    pub fn atan2f(a: c_float, b: c_float) -> c_float;
-    pub fn atanf(n: c_float) -> c_float;
-    pub fn cbrt(n: c_double) -> c_double;
-    pub fn cbrtf(n: c_float) -> c_float;
-    pub fn cosh(n: c_double) -> c_double;
-    pub fn coshf(n: c_float) -> c_float;
-    pub fn expm1(n: c_double) -> c_double;
-    pub fn expm1f(n: c_float) -> c_float;
-    pub fn fdim(a: c_double, b: c_double) -> c_double;
-    pub fn fdimf(a: c_float, b: c_float) -> c_float;
-    pub fn hypot(x: c_double, y: c_double) -> c_double;
-    pub fn hypotf(x: c_float, y: c_float) -> c_float;
-    pub fn log1p(n: c_double) -> c_double;
-    pub fn log1pf(n: c_float) -> c_float;
-    pub fn sinh(n: c_double) -> c_double;
-    pub fn sinhf(n: c_float) -> c_float;
-    pub fn tan(n: c_double) -> c_double;
-    pub fn tanf(n: c_float) -> c_float;
-    pub fn tanh(n: c_double) -> c_double;
-    pub fn tanhf(n: c_float) -> c_float;
+    pub fn acos(n: f64) -> f64;
+    pub fn acosf(n: f32) -> f32;
+    pub fn asin(n: f64) -> f64;
+    pub fn asinf(n: f32) -> f32;
+    pub fn atan(n: f64) -> f64;
+    pub fn atan2(a: f64, b: f64) -> f64;
+    pub fn atan2f(a: f32, b: f32) -> f32;
+    pub fn atanf(n: f32) -> f32;
+    pub fn cbrt(n: f64) -> f64;
+    pub fn cbrtf(n: f32) -> f32;
+    pub fn cosh(n: f64) -> f64;
+    pub fn coshf(n: f32) -> f32;
+    pub fn expm1(n: f64) -> f64;
+    pub fn expm1f(n: f32) -> f32;
+    pub fn fdim(a: f64, b: f64) -> f64;
+    pub fn fdimf(a: f32, b: f32) -> f32;
+    pub fn hypot(x: f64, y: f64) -> f64;
+    pub fn hypotf(x: f32, y: f32) -> f32;
+    pub fn log1p(n: f64) -> f64;
+    pub fn log1pf(n: f32) -> f32;
+    pub fn sinh(n: f64) -> f64;
+    pub fn sinhf(n: f32) -> f32;
+    pub fn tan(n: f64) -> f64;
+    pub fn tanf(n: f32) -> f32;
+    pub fn tanh(n: f64) -> f64;
+    pub fn tanhf(n: f32) -> f32;
 }
diff --git a/library/std/src/sys/unix/mod.rs b/library/std/src/sys/unix/mod.rs
index a0ee69c2f72..6c4fbaf2734 100644
--- a/library/std/src/sys/unix/mod.rs
+++ b/library/std/src/sys/unix/mod.rs
@@ -11,6 +11,7 @@ pub mod weak;
 pub mod alloc;
 pub mod android;
 pub mod args;
+#[path = "../unix/cmath.rs"]
 pub mod cmath;
 pub mod condvar;
 pub mod env;
diff --git a/library/std/src/sys/unsupported/cmath.rs b/library/std/src/sys/unsupported/cmath.rs
deleted file mode 100644
index 304cf906b2a..00000000000
--- a/library/std/src/sys/unsupported/cmath.rs
+++ /dev/null
@@ -1,29 +0,0 @@
-// These symbols are all defined in `compiler-builtins`
-extern "C" {
-    pub fn acos(n: f64) -> f64;
-    pub fn acosf(n: f32) -> f32;
-    pub fn asin(n: f64) -> f64;
-    pub fn asinf(n: f32) -> f32;
-    pub fn atan(n: f64) -> f64;
-    pub fn atan2(a: f64, b: f64) -> f64;
-    pub fn atan2f(a: f32, b: f32) -> f32;
-    pub fn atanf(n: f32) -> f32;
-    pub fn cbrt(n: f64) -> f64;
-    pub fn cbrtf(n: f32) -> f32;
-    pub fn cosh(n: f64) -> f64;
-    pub fn coshf(n: f32) -> f32;
-    pub fn expm1(n: f64) -> f64;
-    pub fn expm1f(n: f32) -> f32;
-    pub fn fdim(a: f64, b: f64) -> f64;
-    pub fn fdimf(a: f32, b: f32) -> f32;
-    pub fn hypot(x: f64, y: f64) -> f64;
-    pub fn hypotf(x: f32, y: f32) -> f32;
-    pub fn log1p(n: f64) -> f64;
-    pub fn log1pf(n: f32) -> f32;
-    pub fn sinh(n: f64) -> f64;
-    pub fn sinhf(n: f32) -> f32;
-    pub fn tan(n: f64) -> f64;
-    pub fn tanf(n: f32) -> f32;
-    pub fn tanh(n: f64) -> f64;
-    pub fn tanhf(n: f32) -> f32;
-}
diff --git a/library/std/src/sys/unsupported/mod.rs b/library/std/src/sys/unsupported/mod.rs
index 32ca68ef15b..3ef4c6b8a8f 100644
--- a/library/std/src/sys/unsupported/mod.rs
+++ b/library/std/src/sys/unsupported/mod.rs
@@ -2,6 +2,7 @@
 
 pub mod alloc;
 pub mod args;
+#[path = "../unix/cmath.rs"]
 pub mod cmath;
 pub mod condvar;
 pub mod env;
diff --git a/library/std/src/sys/wasi/mod.rs b/library/std/src/sys/wasi/mod.rs
index 2584d35b6ef..37f74fcc052 100644
--- a/library/std/src/sys/wasi/mod.rs
+++ b/library/std/src/sys/wasi/mod.rs
@@ -20,7 +20,7 @@ use crate::mem;
 #[path = "../unix/alloc.rs"]
 pub mod alloc;
 pub mod args;
-#[path = "../unsupported/cmath.rs"]
+#[path = "../unix/cmath.rs"]
 pub mod cmath;
 #[path = "../unsupported/condvar.rs"]
 pub mod condvar;
diff --git a/library/std/src/sys/wasm/mod.rs b/library/std/src/sys/wasm/mod.rs
index 8705910c73a..afcc5ca9286 100644
--- a/library/std/src/sys/wasm/mod.rs
+++ b/library/std/src/sys/wasm/mod.rs
@@ -18,7 +18,7 @@
 
 pub mod alloc;
 pub mod args;
-#[path = "../unsupported/cmath.rs"]
+#[path = "../unix/cmath.rs"]
 pub mod cmath;
 pub mod env;
 #[path = "../unsupported/fs.rs"]