diff --git a/libgcc/ChangeLog b/libgcc/ChangeLog
index e08168cc44e..d4abb3b11ca 100644
--- a/libgcc/ChangeLog
+++ b/libgcc/ChangeLog
@@ -1,3 +1,9 @@
+2018-10-03  Uros Bizjak  <ubizjak@gmail.com>
+
+	* libgcc2.c (isnan): Use __builtin_isnan.
+	(isfinite): Use __builtin_isfinite.
+	(isinf): Use __builtin_isinf.
+
 2018-09-26  Uros Bizjak  <ubizjak@gmail.com>
 
 	* config/i386/crtprec.c (set_precision): Use fnstcw instead of fstcw.
@@ -105,7 +111,7 @@
 	unordered store to release lock.
 	(__sync_lock_release_8): Likewise.
 	(SYNC_LOCK_RELEASE_2): Remove define.
-	 
+
 2018-08-02  Nicolas Pitre <nico@fluxnic.net>
 
 	PR libgcc/86512
@@ -416,7 +422,7 @@
 
 	* config/pa/fptr.c (_dl_read_access_allowed): New.
 	(__canonicalize_funcptr_for_compare): Use it.
-	
+
 2018-02-28  Jakub Jelinek  <jakub@redhat.com>
 
 	PR debug/83917
@@ -513,21 +519,21 @@
 	* config/rl78/t-rl78: Added smindi3.S to LIB2ADD.
 
 2018-01-22  Sebastian Perta  <sebastian.perta@renesas.com>
- 
+
 	* config/rl78/smaxdi3.S: New assembly file.
 	* config/rl78/t-rl78: Added smaxdi3.S to LIB2ADD.
 
 2018-01-22  Sebastian Perta  <sebastian.perta@renesas.com>
- 
+
 	* config/rl78/umaxdi3.S: New assembly file.
 	* config/rl78/t-rl78: Added umaxdi3.S to LIB2ADD.
-	
+
 2018-01-21  John David Anglin  <danglin@gcc.gnu.org>
 
 	PR lto/83452
 	* config/pa/stublib.c (L_gnu_lto_v1): New stub definition.
 	* config/pa/t-stublib (gnu_lto_v1-stub.o): Add make fragment.
-	
+
 2018-01-13  Richard Sandiford  <richard.sandiford@linaro.org>
 
 	* config/aarch64/value-unwind.h (aarch64_vg): New function.
diff --git a/libgcc/libgcc2.c b/libgcc/libgcc2.c
index f418f3a354d..8ac2025f7af 100644
--- a/libgcc/libgcc2.c
+++ b/libgcc/libgcc2.c
@@ -1939,15 +1939,9 @@ NAME (TYPE x, int m)
 #define CONCAT2(A,B)	_CONCAT2(A,B)
 #define _CONCAT2(A,B)	A##B
 
-/* All of these would be present in a full C99 implementation of <math.h>
-   and <complex.h>.  Our problem is that only a few systems have such full
-   implementations.  Further, libgcc_s.so isn't currently linked against
-   libm.so, and even for systems that do provide full C99, the extra overhead
-   of all programs using libgcc having to link against libm.  So avoid it.  */
-
-#define isnan(x)	__builtin_expect ((x) != (x), 0)
-#define isfinite(x)	__builtin_expect (!isnan((x) - (x)), 1)
-#define isinf(x)	__builtin_expect (!isnan(x) & !isfinite(x), 0)
+#define isnan(x)	__builtin_isnan (x)
+#define isfinite(x)	__builtin_isfinite (x)
+#define isinf(x)	__builtin_isinf (x)
 
 #define INFINITY	CONCAT2(__builtin_huge_val, CEXT) ()
 #define I		1i