diff --git a/libm/sincos.c b/libm/sincos.c
index e9f6dcc..0259bde 100644
--- a/libm/sincos.c
+++ b/libm/sincos.c
@@ -26,25 +26,143 @@
  */
 #define _GNU_SOURCE 1
 #include <math.h>
+#define INLINE_KERNEL_COSDF
+#define INLINE_KERNEL_SINDF
+#include "src/math_private.h"
+#include "src/k_cosf.c"
+#include "src/k_sinf.c"
 
-// Disable sincos optimization for all functions in this file,
-// otherwise gcc would generate infinite calls.
-// Refer to gcc PR46926.
-// -fno-builtin-sin or -fno-builtin-cos can disable sincos optimization,
-// but these two options do not work inside optimize pragma in-file.
-// Thus we just enforce -O0 when compiling this file.
-#pragma GCC optimize ("O0")
+/* Small multiples of pi/2 rounded to double precision. */
+static const double
+s1pio2 = 1*M_PI_2,            /* 0x3FF921FB, 0x54442D18 */
+s2pio2 = 2*M_PI_2,            /* 0x400921FB, 0x54442D18 */
+s3pio2 = 3*M_PI_2,            /* 0x4012D97C, 0x7F3321D2 */
+s4pio2 = 4*M_PI_2;            /* 0x401921FB, 0x54442D18 */
 
+/* For implementation details, see src/s_sin.c, src/s_cos.c */
 void  sincos(double x, double *psin, double *pcos)
 {
-    *psin = sin(x);
-    *pcos = cos(x);
+    double y[2], z=0.0;
+    int32_t n, ix;
+
+    /* High word of x. */
+    GET_HIGH_WORD(ix, x);
+
+    /* |x| ~< pi/4 */
+    ix &= 0x7fffffff;
+    if(ix <= 0x3fe921fb) {
+        if(ix < 0x3e400000) { /* \x\ < 2**-27 */
+            if((int)x==0) { /* generate inexact */
+                *psin = x;
+                *pcos = 1.0;
+                return;
+            }
+        }
+        *psin = __kernel_sin(x, z, 0);
+        *pcos = __kernel_cos(x, z);
+        return;
+    } else if(ix>=0x7ff00000) { /* sin(Inf or NaN) and cos(Inf or NaN) is NaN */
+        *psin = *pcos = x-x;
+        return;
+    } else {
+        n = __ieee754_rem_pio2(x, y);
+        switch(n&3) {
+            case 0:
+                *psin = __kernel_sin(y[0],y[1],1);
+                *pcos = __kernel_cos(y[0],y[1]);
+                return;
+            case 1:
+                *psin = __kernel_cos(y[0],y[1]);
+                *pcos = -__kernel_sin(y[0],y[1],1);
+                return;
+            case 2:
+                *psin = -__kernel_sin(y[0],y[1],1);
+                *pcos = -__kernel_cos(y[0],y[1]);
+                return;
+            default:
+                *psin = -__kernel_cos(y[0],y[1]);
+                *pcos = __kernel_sin(y[0],y[1],1);
+                return;
+        }
+    }
 }
 
+/* For implementation details, see src/s_sinf.c, src/s_cosf.c */
 void  sincosf(float x, float *psin, float *pcos)
 {
-    *psin = sinf(x);
-    *pcos = cosf(x);
+    float y[2];
+    int32_t n, hx, ix;
+
+    GET_FLOAT_WORD(hx, x);
+    ix = hx & 0x7fffffff;
+
+    if(ix <= 0x3f490fda) {            /* |x| ~<= pi/4 */
+        if(ix < 0x39800000) {        /* |x| < 2**-12 */
+            if(((int)x)==0) {    /* x with inexact if x != 0 */
+                *psin = x;
+                *pcos = 1.0;
+                return;
+            }
+        }
+        *psin = __kernel_sindf(x);
+        *pcos = __kernel_cosdf(x);
+        return;
+    } else if(ix <= 0x407b53d1) {        /* |x| ~<= 5*pi/4 */
+        if(ix <= 0x4016cbe3) {        /* |x| ~<= 3pi/4 */
+            if(hx>0) {
+                *psin = __kernel_cosdf(x - s1pio2);
+                *pcos = __kernel_sindf(s1pio2 - x);
+                return;
+            } else {
+                *psin = -__kernel_cosdf(x + s1pio2);
+                *pcos = __kernel_sindf(x + s1pio2);
+                return;
+            }
+        } else {
+            *psin = __kernel_sindf((hx > 0 ? s2pio2 : -s2pio2) - x);
+            *pcos = -__kernel_cosdf(x + (hx > 0 ? -s2pio2 : s2pio2));
+            return;
+        }
+    } else if(ix <= 0x40e231d5) {        /* |x| ~<= 9*pi/4 */
+        if(ix <= 0x40afeddf) {        /* |x| ~<= 7*pi/4 */
+            if(hx>0) {
+                *psin = -__kernel_cosdf(x - s3pio2);
+                *pcos = __kernel_sindf(x - s3pio2);
+                return;
+            } else {
+                *psin = __kernel_cosdf(x + s3pio2);
+                *pcos = __kernel_sindf(-s3pio2 - x);
+                return;
+            }
+        } else {
+            *psin = __kernel_sindf(x + (hx > 0 ? -s4pio2 : s4pio2));
+            *pcos = __kernel_cosdf(x + (hx > 0 ? -s4pio2 : s4pio2));
+            return;
+        }
+    } else if(ix>=0x7f800000) {        /* sin and cos (Inf or NaN) is NaN */
+        *psin = *pcos = x-x;
+        return;
+    } else {
+        n = __ieee754_rem_pio2f(x,y);
+        switch(n&3) {
+        case 0:
+            *psin = __kernel_sindf((double)y[0]+y[1]);
+            *pcos = __kernel_cosdf((double)y[0]+y[1]);
+            return;
+        case 1:
+            *psin = __kernel_cosdf((double)y[0]+y[1]);
+            *pcos = __kernel_sindf(-(double)y[0]-y[1]);
+            return;
+        case 2:
+            *psin = __kernel_sindf(-(double)y[0]-y[1]);
+            *pcos = -__kernel_cosdf((double)y[0]+y[1]);
+            return;
+        default:
+            *psin = -__kernel_cosdf((double)y[0]+y[1]);
+            *pcos = __kernel_sindf((double)y[0]+y[1]);
+            return;
+        }
+    }
 }
 
 void  sincosl(long double x, long double *psin, long double *pcos)