diff --git a/libgcc/config/rs6000/_divkc3.c b/libgcc/config/rs6000/_divkc3.c
index 9f52428cfa0aaba1b356c14a5c8efc507b4245c8..b5f9e59627d0c3aadb9f3f67423f133a4d1906ce 100644
--- a/libgcc/config/rs6000/_divkc3.c
+++ b/libgcc/config/rs6000/_divkc3.c
@@ -26,9 +26,19 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #include "soft-fp.h"
 #include "quad-float128.h"
 
+/* Use the correct built-in function based on whether TFmode is _Float128 or
+   long double.  See quad-float128.h for more details.  */
+#ifndef __LONG_DOUBLE_IEEE128__
 #define COPYSIGN(x,y) __builtin_copysignf128 (x, y)
 #define INFINITY __builtin_inff128 ()
 #define FABS __builtin_fabsf128
+
+#else
+#define COPYSIGN(x,y) __builtin_copysignl (x, y)
+#define INFINITY __builtin_infl ()
+#define FABS __builtin_fabsl
+#endif
+
 #define isnan __builtin_isnan
 #define isinf __builtin_isinf
 #define isfinite __builtin_isfinite
diff --git a/libgcc/config/rs6000/_mulkc3.c b/libgcc/config/rs6000/_mulkc3.c
index 299d8d147b00a5c033cf3b1fe73da66f59ece943..a01cb0540547f22ffe368cfa5ef19590e1577734 100644
--- a/libgcc/config/rs6000/_mulkc3.c
+++ b/libgcc/config/rs6000/_mulkc3.c
@@ -26,8 +26,17 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #include "soft-fp.h"
 #include "quad-float128.h"
 
+/* Use the correct built-in function based on whether TFmode is _Float128 or
+   long double.  See quad-float128.h for more details.  */
+#ifndef __LONG_DOUBLE_IEEE128__
 #define COPYSIGN(x,y) __builtin_copysignf128 (x, y)
 #define INFINITY __builtin_inff128 ()
+
+#else
+#define COPYSIGN(x,y) __builtin_copysignl (x, y)
+#define INFINITY __builtin_infl ()
+#endif
+
 #define isnan __builtin_isnan
 #define isinf __builtin_isinf
 
diff --git a/libgcc/config/rs6000/quad-float128.h b/libgcc/config/rs6000/quad-float128.h
index 68bd9b97f2396456162efaf55c73af7e90cb4d85..974912326ba9aa82d89c57816e52c1a3c4202660 100644
--- a/libgcc/config/rs6000/quad-float128.h
+++ b/libgcc/config/rs6000/quad-float128.h
@@ -27,21 +27,37 @@
    License along with the GNU C Library; if not, see
    <http://www.gnu.org/licenses/>.  */
 
-/* quad.h defines the TFtype type by:
-   typedef float TFtype __attribute__ ((mode (TF)));
+/* Override the types for IEEE 128-bit scalar and complex.  We need to use the
+   same IEEE 128-bit type (either long double or _Float128) for both the
+   128-bit scalar type and for the base type in _Complex.  Otherwise, if
+   different types are used, there may be problems in mixing _Complex values
+   with the scalar value.
 
-   This define forces it to use KFmode (aka, ieee 128-bit floating point).
-   However, when the compiler's default is changed so that long double is IEEE
-   128-bit floating point, we need to go back to using TFmode and TCmode.  */
-#ifndef __LONG_DOUBLE_IEEE128__
-#define TF KF
+   We can't use _Compelx _float128 since GCC doesn't allow it.  It only allows
+   _Complex for _Float128 or for long double.
 
-/* We also need TCtype to represent complex ieee 128-bit float for
-   __mulkc3 and __divkc3.  */
-typedef __complex float TCtype __attribute__ ((mode (KC)));
+   We use _Float128 when long double is IBM double-double or 64-bit, and long
+   double when long double uses the IEEE 128-bit type.  We need to do this
+   because the compiler has a built-in prototype for __mulkc3 and __divkc3
+   using those types.  Since we are declaring these functions here, we need to
+   use the same type that the compiler uses (i.e. we can't just always use
+   _Float128).
+
+   Even though the type _Float128 and long double (when long double uses IEEE
+   128-bits) both hold IEEE 128-bit values, the front ends treat these as two
+   separate types.
+
+   The extension keyword __float128 is currently problematical because it can
+   either be a synonym for _Float128 (when long double is IBM) or for long
+   double (when long double is IEEE).  */
+
+#ifdef __LONG_DOUBLE_IEEE128__
+#define TFtype long double
+#define TCtype _Complex long double
 
 #else
-typedef __complex float TCtype __attribute__ ((mode (TC)));
+#define TFtype _Float128
+#define TCtype _Complex _Float128
 #endif
 
 /* Force the use of the VSX instruction set.  */
diff --git a/libgcc/libgcc2.h b/libgcc/libgcc2.h
index 6f42db7f0beb859424221f86ebb078ff8e648a26..3ec9bbd81647514e299fec6b445e48b21c88943b 100644
--- a/libgcc/libgcc2.h
+++ b/libgcc/libgcc2.h
@@ -156,9 +156,13 @@ typedef		float XFtype	__attribute__ ((mode (XF)));
 typedef _Complex float XCtype	__attribute__ ((mode (XC)));
 #endif
 #if LIBGCC2_HAS_TF_MODE
+#ifndef TFtype
 typedef		float TFtype	__attribute__ ((mode (TF)));
+#endif
+#ifndef TCtype
 typedef _Complex float TCtype	__attribute__ ((mode (TC)));
 #endif
+#endif
 
 typedef int cmp_return_type __attribute__((mode (__libgcc_cmp_return__)));
 typedef int shift_count_type __attribute__((mode (__libgcc_shift_count__)));
diff --git a/libgcc/soft-fp/quad.h b/libgcc/soft-fp/quad.h
index 3889bb44f1fdc17fa122fc827144c8a0027ca9b7..71f87d36ba9801ac0aabc1d87cb947a413b5a9fc 100644
--- a/libgcc/soft-fp/quad.h
+++ b/libgcc/soft-fp/quad.h
@@ -65,7 +65,9 @@
 #define _FP_HIGHBIT_DW_Q	\
   ((_FP_W_TYPE) 1 << (_FP_WFRACBITS_DW_Q - 1) % _FP_W_TYPE_SIZE)
 
+#ifndef TFtype
 typedef float TFtype __attribute__ ((mode (TF)));
+#endif
 
 #if _FP_W_TYPE_SIZE < 64