diff --git a/gcc/config/alpha/linux.h b/gcc/config/alpha/linux.h
index c567f43..475ea06 100644
--- a/gcc/config/alpha/linux.h
+++ b/gcc/config/alpha/linux.h
@@ -61,10 +61,14 @@ along with GCC; see the file COPYING3.  If not see
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 /* Determine what functions are present at the runtime;
diff --git a/gcc/config/glibc-stdint.h b/gcc/config/glibc-stdint.h
index 3fc67dc..98f4f04 100644
--- a/gcc/config/glibc-stdint.h
+++ b/gcc/config/glibc-stdint.h
@@ -22,6 +22,12 @@ a copy of the GCC Runtime Library Exception along with this program;
 see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 <http://www.gnu.org/licenses/>.  */
 
+/* Systems using musl libc should use this header and make sure
+   OPTION_MUSL is defined correctly before using the TYPE macros. */
+#ifndef OPTION_MUSL
+#define OPTION_MUSL 0
+#endif
+
 #define SIG_ATOMIC_TYPE "int"
 
 #define INT8_TYPE "signed char"
@@ -43,12 +49,12 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define UINT_LEAST64_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "long long unsigned int")
 
 #define INT_FAST8_TYPE "signed char"
-#define INT_FAST16_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "int")
-#define INT_FAST32_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "int")
+#define INT_FAST16_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long int" : "int")
+#define INT_FAST32_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long int" : "int")
 #define INT_FAST64_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "long long int")
 #define UINT_FAST8_TYPE "unsigned char"
-#define UINT_FAST16_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "unsigned int")
-#define UINT_FAST32_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "unsigned int")
+#define UINT_FAST16_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long unsigned int" : "unsigned int")
+#define UINT_FAST32_TYPE (LONG_TYPE_SIZE == 64 && !OPTION_MUSL ? "long unsigned int" : "unsigned int")
 #define UINT_FAST64_TYPE (LONG_TYPE_SIZE == 64 ? "long unsigned int" : "long long unsigned int")
 
 #define INTPTR_TYPE (LONG_TYPE_SIZE == 64 ? "long int" : "int")
diff --git a/gcc/config/linux.h b/gcc/config/linux.h
index b551c56..7bc87ab 100644
--- a/gcc/config/linux.h
+++ b/gcc/config/linux.h
@@ -32,11 +32,13 @@ see the files COPYING3 and COPYING.RUNTIME respectively.  If not, see
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
 #define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
 #define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
diff --git a/gcc/config/rs6000/linux.h b/gcc/config/rs6000/linux.h
index fe0ebd6..a68ff69 100644
--- a/gcc/config/rs6000/linux.h
+++ b/gcc/config/rs6000/linux.h
@@ -30,10 +30,14 @@
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 /* Determine what functions are present at the runtime;
diff --git a/gcc/config/rs6000/linux64.h b/gcc/config/rs6000/linux64.h
index 0879e7e..1b7f695 100644
--- a/gcc/config/rs6000/linux64.h
+++ b/gcc/config/rs6000/linux64.h
@@ -299,10 +299,14 @@ extern int dot_symbols;
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (DEFAULT_LIBC == LIBC_MUSL)
 #else
 #define OPTION_GLIBC  (linux_libc == LIBC_GLIBC)
 #define OPTION_UCLIBC (linux_libc == LIBC_UCLIBC)
 #define OPTION_BIONIC (linux_libc == LIBC_BIONIC)
+#undef OPTION_MUSL
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 /* Determine what functions are present at the runtime;