Index: lib/builtins/divdc3.c
===================================================================
--- lib/builtins/divdc3.c
+++ lib/builtins/divdc3.c
@@ -17,7 +17,7 @@
 
 /* Returns: the quotient of (a + ib) / (c + id) */
 
-COMPILER_RT_ABI double _Complex
+COMPILER_RT_ABI Dcomplex
 __divdc3(double __a, double __b, double __c, double __d)
 {
     int __ilogbw = 0;
@@ -29,31 +29,31 @@
         __d = crt_scalbn(__d, -__ilogbw);
     }
     double __denom = __c * __c + __d * __d;
-    double _Complex z;
-    __real__ z = crt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
-    __imag__ z = crt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
-    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
+    Dcomplex z;
+    COMPLEX_REAL(z) = crt_scalbn((__a * __c + __b * __d) / __denom, -__ilogbw);
+    COMPLEX_IMAGINARY(z) = crt_scalbn((__b * __c - __a * __d) / __denom, -__ilogbw);
+    if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
     {
         if ((__denom == 0.0) && (!crt_isnan(__a) || !crt_isnan(__b)))
         {
-            __real__ z = crt_copysign(CRT_INFINITY, __c) * __a;
-            __imag__ z = crt_copysign(CRT_INFINITY, __c) * __b;
+            COMPLEX_REAL(z) = crt_copysign(CRT_INFINITY, __c) * __a;
+            COMPLEX_IMAGINARY(z) = crt_copysign(CRT_INFINITY, __c) * __b;
         }
         else if ((crt_isinf(__a) || crt_isinf(__b)) &&
                  crt_isfinite(__c) && crt_isfinite(__d))
         {
             __a = crt_copysign(crt_isinf(__a) ? 1.0 : 0.0, __a);
             __b = crt_copysign(crt_isinf(__b) ? 1.0 : 0.0, __b);
-            __real__ z = CRT_INFINITY * (__a * __c + __b * __d);
-            __imag__ z = CRT_INFINITY * (__b * __c - __a * __d);
+            COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c + __b * __d);
+            COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__b * __c - __a * __d);
         }
         else if (crt_isinf(__logbw) && __logbw > 0.0 &&
                  crt_isfinite(__a) && crt_isfinite(__b))
         {
             __c = crt_copysign(crt_isinf(__c) ? 1.0 : 0.0, __c);
             __d = crt_copysign(crt_isinf(__d) ? 1.0 : 0.0, __d);
-            __real__ z = 0.0 * (__a * __c + __b * __d);
-            __imag__ z = 0.0 * (__b * __c - __a * __d);
+            COMPLEX_REAL(z) = 0.0 * (__a * __c + __b * __d);
+            COMPLEX_IMAGINARY(z) = 0.0 * (__b * __c - __a * __d);
         }
     }
     return z;
Index: lib/builtins/divsc3.c
===================================================================
--- lib/builtins/divsc3.c
+++ lib/builtins/divsc3.c
@@ -17,7 +17,7 @@
 
 /* Returns: the quotient of (a + ib) / (c + id) */
 
-COMPILER_RT_ABI float _Complex
+COMPILER_RT_ABI Fcomplex
 __divsc3(float __a, float __b, float __c, float __d)
 {
     int __ilogbw = 0;
@@ -29,31 +29,31 @@
         __d = crt_scalbnf(__d, -__ilogbw);
     }
     float __denom = __c * __c + __d * __d;
-    float _Complex z;
-    __real__ z = crt_scalbnf((__a * __c + __b * __d) / __denom, -__ilogbw);
-    __imag__ z = crt_scalbnf((__b * __c - __a * __d) / __denom, -__ilogbw);
-    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
+    Fcomplex z;
+    COMPLEX_REAL(z) = crt_scalbnf((__a * __c + __b * __d) / __denom, -__ilogbw);
+    COMPLEX_IMAGINARY(z) = crt_scalbnf((__b * __c - __a * __d) / __denom, -__ilogbw);
+    if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
     {
         if ((__denom == 0) && (!crt_isnan(__a) || !crt_isnan(__b)))
         {
-            __real__ z = crt_copysignf(CRT_INFINITY, __c) * __a;
-            __imag__ z = crt_copysignf(CRT_INFINITY, __c) * __b;
+            COMPLEX_REAL(z) = crt_copysignf(CRT_INFINITY, __c) * __a;
+            COMPLEX_IMAGINARY(z) = crt_copysignf(CRT_INFINITY, __c) * __b;
         }
         else if ((crt_isinf(__a) || crt_isinf(__b)) &&
                  crt_isfinite(__c) && crt_isfinite(__d))
         {
             __a = crt_copysignf(crt_isinf(__a) ? 1 : 0, __a);
             __b = crt_copysignf(crt_isinf(__b) ? 1 : 0, __b);
-            __real__ z = CRT_INFINITY * (__a * __c + __b * __d);
-            __imag__ z = CRT_INFINITY * (__b * __c - __a * __d);
+            COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c + __b * __d);
+            COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__b * __c - __a * __d);
         }
         else if (crt_isinf(__logbw) && __logbw > 0 &&
                  crt_isfinite(__a) && crt_isfinite(__b))
         {
             __c = crt_copysignf(crt_isinf(__c) ? 1 : 0, __c);
             __d = crt_copysignf(crt_isinf(__d) ? 1 : 0, __d);
-            __real__ z = 0 * (__a * __c + __b * __d);
-            __imag__ z = 0 * (__b * __c - __a * __d);
+            COMPLEX_REAL(z) = 0 * (__a * __c + __b * __d);
+            COMPLEX_IMAGINARY(z) = 0 * (__b * __c - __a * __d);
         }
     }
     return z;
Index: lib/builtins/divxc3.c
===================================================================
--- lib/builtins/divxc3.c
+++ lib/builtins/divxc3.c
@@ -18,7 +18,7 @@
 
 /* Returns: the quotient of (a + ib) / (c + id) */
 
-COMPILER_RT_ABI long double _Complex
+COMPILER_RT_ABI Lcomplex
 __divxc3(long double __a, long double __b, long double __c, long double __d)
 {
     int __ilogbw = 0;
@@ -30,31 +30,31 @@
         __d = crt_scalbnl(__d, -__ilogbw);
     }
     long double __denom = __c * __c + __d * __d;
-    long double _Complex z;
-    __real__ z = crt_scalbnl((__a * __c + __b * __d) / __denom, -__ilogbw);
-    __imag__ z = crt_scalbnl((__b * __c - __a * __d) / __denom, -__ilogbw);
-    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
+    Lcomplex z;
+    COMPLEX_REAL(z) = crt_scalbnl((__a * __c + __b * __d) / __denom, -__ilogbw);
+    COMPLEX_IMAGINARY(z) = crt_scalbnl((__b * __c - __a * __d) / __denom, -__ilogbw);
+    if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
     {
         if ((__denom == 0) && (!crt_isnan(__a) || !crt_isnan(__b)))
         {
-            __real__ z = crt_copysignl(CRT_INFINITY, __c) * __a;
-            __imag__ z = crt_copysignl(CRT_INFINITY, __c) * __b;
+            COMPLEX_REAL(z) = crt_copysignl(CRT_INFINITY, __c) * __a;
+            COMPLEX_IMAGINARY(z) = crt_copysignl(CRT_INFINITY, __c) * __b;
         }
         else if ((crt_isinf(__a) || crt_isinf(__b)) &&
                  crt_isfinite(__c) && crt_isfinite(__d))
         {
             __a = crt_copysignl(crt_isinf(__a) ? 1 : 0, __a);
             __b = crt_copysignl(crt_isinf(__b) ? 1 : 0, __b);
-            __real__ z = CRT_INFINITY * (__a * __c + __b * __d);
-            __imag__ z = CRT_INFINITY * (__b * __c - __a * __d);
+            COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c + __b * __d);
+            COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__b * __c - __a * __d);
         }
         else if (crt_isinf(__logbw) && __logbw > 0 &&
                  crt_isfinite(__a) && crt_isfinite(__b))
         {
             __c = crt_copysignl(crt_isinf(__c) ? 1 : 0, __c);
             __d = crt_copysignl(crt_isinf(__d) ? 1 : 0, __d);
-            __real__ z = 0 * (__a * __c + __b * __d);
-            __imag__ z = 0 * (__b * __c - __a * __d);
+            COMPLEX_REAL(z) = 0 * (__a * __c + __b * __d);
+            COMPLEX_IMAGINARY(z) = 0 * (__b * __c - __a * __d);
         }
     }
     return z;
Index: lib/builtins/int_types.h
===================================================================
--- lib/builtins/int_types.h
+++ lib/builtins/int_types.h
@@ -140,5 +140,22 @@
     long double f;
 } long_double_bits;
 
+#if __STDC_VERSION__ >= 199901L
+typedef float _Complex Fcomplex;
+typedef double _Complex Dcomplex;
+typedef long double _Complex Lcomplex;
+
+#define COMPLEX_REAL(x) __real__(x)
+#define COMPLEX_IMAGINARY(x) __imag__(x)
+#else
+typedef struct { float real, imaginary; } Fcomplex;
+
+typedef struct { double real, imaginary; } Dcomplex;
+
+typedef struct { long double real, imaginary; } Lcomplex;
+
+#define COMPLEX_REAL(x) (x).real
+#define COMPLEX_IMAGINARY(x) (x).imaginary
+#endif
 #endif /* INT_TYPES_H */
 
Index: lib/builtins/muldc3.c
===================================================================
--- lib/builtins/muldc3.c
+++ lib/builtins/muldc3.c
@@ -17,17 +17,17 @@
 
 /* Returns: the product of a + ib and c + id */
 
-COMPILER_RT_ABI double _Complex
+COMPILER_RT_ABI Dcomplex
 __muldc3(double __a, double __b, double __c, double __d)
 {
     double __ac = __a * __c;
     double __bd = __b * __d;
     double __ad = __a * __d;
     double __bc = __b * __c;
-    double _Complex z;
-    __real__ z = __ac - __bd;
-    __imag__ z = __ad + __bc;
-    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
+    Dcomplex z;
+    COMPLEX_REAL(z) = __ac - __bd;
+    COMPLEX_IMAGINARY(z) = __ad + __bc;
+    if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
     {
         int __recalc = 0;
         if (crt_isinf(__a) || crt_isinf(__b))
@@ -65,8 +65,8 @@
         }
         if (__recalc)
         {
-            __real__ z = CRT_INFINITY * (__a * __c - __b * __d);
-            __imag__ z = CRT_INFINITY * (__a * __d + __b * __c);
+            COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c - __b * __d);
+            COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__a * __d + __b * __c);
         }
     }
     return z;
Index: lib/builtins/mulsc3.c
===================================================================
--- lib/builtins/mulsc3.c
+++ lib/builtins/mulsc3.c
@@ -17,17 +17,17 @@
 
 /* Returns: the product of a + ib and c + id */
 
-COMPILER_RT_ABI float _Complex
+COMPILER_RT_ABI Fcomplex
 __mulsc3(float __a, float __b, float __c, float __d)
 {
     float __ac = __a * __c;
     float __bd = __b * __d;
     float __ad = __a * __d;
     float __bc = __b * __c;
-    float _Complex z;
-    __real__ z = __ac - __bd;
-    __imag__ z = __ad + __bc;
-    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
+    Fcomplex z;
+    COMPLEX_REAL(z) = __ac - __bd;
+    COMPLEX_IMAGINARY(z) = __ad + __bc;
+    if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
     {
         int __recalc = 0;
         if (crt_isinf(__a) || crt_isinf(__b))
@@ -65,8 +65,8 @@
         }
         if (__recalc)
         {
-            __real__ z = CRT_INFINITY * (__a * __c - __b * __d);
-            __imag__ z = CRT_INFINITY * (__a * __d + __b * __c);
+            COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c - __b * __d);
+            COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__a * __d + __b * __c);
         }
     }
     return z;
Index: lib/builtins/mulxc3.c
===================================================================
--- lib/builtins/mulxc3.c
+++ lib/builtins/mulxc3.c
@@ -19,17 +19,17 @@
 
 /* Returns: the product of a + ib and c + id */
 
-COMPILER_RT_ABI long double _Complex
+COMPILER_RT_ABI Lcomplex
 __mulxc3(long double __a, long double __b, long double __c, long double __d)
 {
     long double __ac = __a * __c;
     long double __bd = __b * __d;
     long double __ad = __a * __d;
     long double __bc = __b * __c;
-    long double _Complex z;
-    __real__ z = __ac - __bd;
-    __imag__ z = __ad + __bc;
-    if (crt_isnan(__real__ z) && crt_isnan(__imag__ z))
+    Lcomplex z;
+    COMPLEX_REAL(z) = __ac - __bd;
+    COMPLEX_IMAGINARY(z) = __ad + __bc;
+    if (crt_isnan(COMPLEX_REAL(z)) && crt_isnan(COMPLEX_IMAGINARY(z)))
     {
         int __recalc = 0;
         if (crt_isinf(__a) || crt_isinf(__b))
@@ -67,8 +67,8 @@
         }
         if (__recalc)
         {
-            __real__ z = CRT_INFINITY * (__a * __c - __b * __d);
-            __imag__ z = CRT_INFINITY * (__a * __d + __b * __c);
+            COMPLEX_REAL(z) = CRT_INFINITY * (__a * __c - __b * __d);
+            COMPLEX_IMAGINARY(z) = CRT_INFINITY * (__a * __d + __b * __c);
         }
     }
     return z;