diff --git a/lib/msun/ld128/s_sinpil.c b/lib/msun/ld128/s_sinpil.c
index 39eed9b007b..cdfa2bcac3e 100644
--- a/lib/msun/ld128/s_sinpil.c
+++ b/lib/msun/ld128/s_sinpil.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2017 Steven G. Kargl
+ * Copyright (c) 2017-2021 Steven G. Kargl
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,9 +26,6 @@
 
 /*
  * See ../src/s_sinpi.c for implementation details.
- *
- * FIXME:  This has not been compiled nor has it been tested for accuracy.
- * FIXME:  This should use bit twiddling.
  */
 
 #include "math.h"
@@ -68,7 +65,7 @@ sinpil(long double x)
 			}
 
 			s = __kernel_sinpil(ax);
-			return (copysignl(s, x));
+			return (x < 0 ? -s : s);
 		}
 
 		if (ax < 0.5)
@@ -77,12 +74,18 @@ sinpil(long double x)
 			s = __kernel_cospil(ax - 0.5);
 		else
 			s = __kernel_sinpil(1 - ax);
-		return (copysignl(s, x));
+		return (x < 0 ? -s : s);
 	}
 
 	if (ax < 0x1p112) {
-		xf = floorl(ax);
-		ax -= xf;
+		/* Split x = n + r with 0 <= r < 1. */
+		xf = (ax + 0x1p112L) - 0x1p112L;        /* Integer part */
+		ax -= xf;                               /* Remainder */
+		if (ax < 0) {
+			ax += 1;
+			xf -= 1;
+		}
+
 		if (ax == 0) {
 			s = 0;
 		} else {
@@ -98,14 +101,14 @@ sinpil(long double x)
 					s = __kernel_sinpil(1 - ax);
 			}
 
-			if (xf > 0x1p50)
-				xf -= 0x1p50;
-			if (xf > 0x1p30)
-				xf -= 0x1p30;
+			if (xf > 0x1p64)
+				xf -= 0x1p64;
+			if (xf > 0x1p32)
+				xf -= 0x1p32;
 			ix = (uint32_t)xf;
 			if (ix & 1) s = -s;
 		}
-		return (copysignl(s, x));
+		return (x < 0 ? -s : s);
 	}
 
 	if (isinf(x) || isnan(x))
diff --git a/lib/msun/ld128/s_cospil.c b/lib/msun/ld128/s_cospil.c
index b4bc50bb4d8..71acc4485f7 100644
--- a/lib/msun/ld128/s_cospil.c
+++ b/lib/msun/ld128/s_cospil.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2017 Steven G. Kargl
+ * Copyright (c) 2017-2021 Steven G. Kargl
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,9 +26,6 @@
 
 /*
  * See ../src/s_cospi.c for implementation details.
- *
- * FIXME:  This has not been compiled nor has it been tested for accuracy.
- * FIXME:  This should use bit twiddling.
  */
 
 #include "math.h"
@@ -54,7 +51,7 @@ cospil(long double x)
 
 	ax = fabsl(x);
 
-	if (ax < 1) {
+	if (ax <= 1) {
 		if (ax < 0.25) {
 			if (ax < 0x1p-60) {
 				if ((int)x == 0)
@@ -75,15 +72,21 @@ cospil(long double x)
 	}
 
 	if (ax < 0x1p112) {
-		xf = floorl(ax);
-		ax -= xf;
-		if (x < 0.5) {
-			if (x < 0.25)
+		/* Split x = n + r with 0 <= r < 1. */
+		xf = (ax + 0x1p112L) - 0x1p112L;        /* Integer part */
+		ax -= xf;                               /* Remainder */
+		if (ax < 0) {
+			ax += 1;
+			xf -= 1;
+		}
+
+		if (ax < 0.5) {
+			if (ax < 0.25)
 				c = ax == 0 ? 1 : __kernel_cospil(ax);
 			else
 				c = __kernel_sinpil(0.5 - ax);
 		} else {
-			if (x < 0.75) {
+			if (ax < 0.75) {
 				if (ax == 0.5)
 					return (0);
 				c = -__kernel_sinpil(ax - 0.5);
@@ -91,10 +94,10 @@ cospil(long double x)
 				c = -__kernel_cospil(1 - ax);
 		}
 
-		if (xf > 0x1p50)
-			xf -= 0x1p50;
-		if (xf > 0x1p30)
-			xf -= 0x1p30;
+		if (xf > 0x1p64)
+			xf -= 0x1p64;
+		if (xf > 0x1p32)
+			xf -= 0x1p32;
 		ix = (uint32_t)xf;
 		return (ix & 1 ? -c : c);
 	}
diff --git a/lib/msun/ld128/s_tanpil.c b/lib/msun/ld128/s_tanpil.c
index 7cbbdc8a5d0..90f4aea5c62 100644
--- a/lib/msun/ld128/s_tanpil.c
+++ b/lib/msun/ld128/s_tanpil.c
@@ -1,5 +1,5 @@
 /*-
- * Copyright (c) 2017 Steven G. Kargl
+ * Copyright (c) 2017-2021 Steven G. Kargl
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,9 +26,6 @@
 
 /*
  * See ../src/s_tanpi.c for implementation details.
- *
- * FIXME: This has not been compiled nor has it been tested for accuracy.
- * FIXME: This should use bit twiddling.
  */
 
 #include "math.h"
@@ -75,7 +72,7 @@ tanpil(long double x)
 	long double ax, hi, lo, xf, t;
 	uint32_t ix;
 
-	ax = fabsl(ax);
+	ax = fabsl(x);
 
 	if (ax < 1) {
 		if (ax < 0.5) {
@@ -94,19 +91,25 @@ tanpil(long double x)
 			return ((ax - ax) / (ax - ax));
 		else
 			t = -__kernel_tanpil(1 - ax);
-		return (copysignl(t, x));
+		return (x < 0 ? -t : t);
 	}
 
 	if (ix < 0x1p112) {
-		xf = floorl(ax);
-		ax -= xf;
+		/* Split x = n + r with 0 <= r < 1. */
+		xf = (ax + 0x1p112L) - 0x1p112L;        /* Integer part */
+		ax -= xf;                               /* Remainder */
+		if (ax < 0) {
+			ax += 1;
+			xf -= 1;
+		}
+
 		if (ax < 0.5)
 			t = ax == 0 ? 0 : __kernel_tanpil(ax);
 		else if (ax == 0.5)
 			return ((ax - ax) / (ax - ax));
 		else
 			t = -__kernel_tanpil(1 - ax);
-		return (copysignl(t, x));
+		return (x < 0 ? -t : t);
 	}
 
 	/* x = +-inf or nan. */
@@ -114,7 +117,7 @@ tanpil(long double x)
 		return (vzero / vzero);
 
 	/*
-	 * |x| >= 0x1p53 is always an integer, so return +-0.
+	 * |x| >= 0x1p112 is always an integer, so return +-0.
 	 */
 	return (copysignl(0, x));
 }