diff --git a/config.sub b/config.sub
--- a/config.sub
+++ b/config.sub
@@ -125,6 +125,7 @@
 maybe_os=`echo $1 | sed 's/^\(.*\)-\([^-]*-[^-]*\)$/\2/'`
 case $maybe_os in
   nto-qnx* | linux-gnu* | linux-android* | linux-dietlibc | linux-newlib* | \
+  linux-musl* | \
   linux-uclibc* | uclinux-uclibc* | uclinux-gnu* | kfreebsd*-gnu* | \
   knetbsd*-gnu* | netbsd*-gnu* | \
   kopensolaris*-gnu* | \
@@ -1346,6 +1347,7 @@
 	      | -cygwin* | -pe* | -psos* | -moss* | -proelf* | -rtems* \
 	      | -mingw32* | -linux-gnu* | -linux-android* \
 	      | -linux-newlib* | -linux-uclibc* \
+	      | -linux-musl* \
 	      | -uxpv* | -beos* | -mpeix* | -udk* \
 	      | -interix* | -uwin* | -mks* | -rhapsody* | -darwin* | -opened* \
 	      | -openstep* | -oskit* | -conix* | -pw32* | -nonstopux* \
diff --git a/gcc/config.gcc b/gcc/config.gcc
--- a/gcc/config.gcc
+++ b/gcc/config.gcc
@@ -522,7 +522,7 @@
 esac
 
 # Common C libraries.
-tm_defines="$tm_defines LIBC_GLIBC=1 LIBC_UCLIBC=2 LIBC_BIONIC=3"
+tm_defines="$tm_defines LIBC_GLIBC=1 LIBC_UCLIBC=2 LIBC_BIONIC=3 LIBC_MUSL=4"
 
 # Common parts for widely ported systems.
 case ${target} in
@@ -625,6 +625,9 @@
     *-*-*uclibc*)
       tm_defines="$tm_defines DEFAULT_LIBC=LIBC_UCLIBC"
       ;;
+    *-*-*musl*)
+      tm_defines="$tm_defines DEFAULT_LIBC=LIBC_MUSL"
+      ;;
     *)
       tm_defines="$tm_defines DEFAULT_LIBC=LIBC_GLIBC"
       ;;
@@ -1722,6 +1725,7 @@
 	tm_file="${tm_file} dbxelf.h gnu-user.h linux.h microblaze/linux.h"
 	c_target_objs="${c_target_objs} microblaze-c.o"
 	cxx_target_objs="${cxx_target_objs} microblaze-c.o"
+        tmake_file="${tmake_file} microblaze/t-microblaze"
 	;;
 microblaze*-*-*)
         tm_file="${tm_file} dbxelf.h"
diff --git a/gcc/config/arm/linux-eabi.h b/gcc/config/arm/linux-eabi.h
--- a/gcc/config/arm/linux-eabi.h
+++ b/gcc/config/arm/linux-eabi.h
@@ -64,6 +64,10 @@
 #undef  GLIBC_DYNAMIC_LINKER
 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.3"
 
+/* musl has no "classic" (i.e. broken) mode */
+#undef  MUSL_DYNAMIC_LINKER
+#define MUSL_DYNAMIC_LINKER "/lib/ld-musl-arm.so.1"
+
 /* At this point, bpabi.h will have clobbered LINK_SPEC.  We want to
    use the GNU/Linux version, not the generic BPABI version.  */
 #undef  LINK_SPEC
diff --git a/gcc/config/i386/linux.h b/gcc/config/i386/linux.h
--- a/gcc/config/i386/linux.h
+++ b/gcc/config/i386/linux.h
@@ -22,3 +22,4 @@
 
 #define GNU_USER_LINK_EMULATION "elf_i386"
 #define GLIBC_DYNAMIC_LINKER "/lib/ld-linux.so.2"
+#define MUSL_DYNAMIC_LINKER "/lib/ld-musl-i386.so.1"
diff --git a/gcc/config/i386/linux64.h b/gcc/config/i386/linux64.h
--- a/gcc/config/i386/linux64.h
+++ b/gcc/config/i386/linux64.h
@@ -31,3 +31,7 @@
 #define GLIBC_DYNAMIC_LINKER32 "/lib/ld-linux.so.2"
 #define GLIBC_DYNAMIC_LINKER64 "/lib64/ld-linux-x86-64.so.2"
 #define GLIBC_DYNAMIC_LINKERX32 "/libx32/ld-linux-x32.so.2"
+
+#define MUSL_DYNAMIC_LINKER32 "/lib/ld-musl-i386.so.1"
+#define MUSL_DYNAMIC_LINKER64 "/lib/ld-musl-x86_64.so.1"
+#define MUSL_DYNAMIC_LINKERX32 "/lib/ld-musl-x32.so.1"
diff --git a/gcc/config/linux.h b/gcc/config/linux.h
--- a/gcc/config/linux.h
+++ b/gcc/config/linux.h
@@ -33,10 +33,12 @@
 #define OPTION_GLIBC  (DEFAULT_LIBC == LIBC_GLIBC)
 #define OPTION_UCLIBC (DEFAULT_LIBC == LIBC_UCLIBC)
 #define OPTION_BIONIC (DEFAULT_LIBC == LIBC_BIONIC)
+#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)
+#define OPTION_MUSL   (linux_libc == LIBC_MUSL)
 #endif
 
 #define GNU_USER_TARGET_OS_CPP_BUILTINS()			\
@@ -54,18 +56,21 @@
    uClibc or Bionic is the default C library and whether
    -muclibc or -mglibc or -mbionic has been passed to change the default.  */
 
-#define CHOOSE_DYNAMIC_LINKER1(LIBC1, LIBC2, LIBC3, LD1, LD2, LD3)	\
-  "%{" LIBC2 ":" LD2 ";:%{" LIBC3 ":" LD3 ";:" LD1 "}}"
+#define CHOOSE_DYNAMIC_LINKER1(LIBC1, LIBC2, LIBC3, LIBC4, LD1, LD2, LD3, LD4)	\
+  "%{" LIBC2 ":" LD2 ";:%{" LIBC3 ":" LD3 ";:%{" LIBC4 ":" LD4 ";:" LD1 "}}}"
 
 #if DEFAULT_LIBC == LIBC_GLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
-  CHOOSE_DYNAMIC_LINKER1 ("mglibc", "muclibc", "mbionic", G, U, B)
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("mglibc", "muclibc", "mbionic", "mmusl", G, U, B, M)
 #elif DEFAULT_LIBC == LIBC_UCLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
-  CHOOSE_DYNAMIC_LINKER1 ("muclibc", "mglibc", "mbionic", U, G, B)
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("muclibc", "mglibc", "mbionic", "mmusl", U, G, B, M)
 #elif DEFAULT_LIBC == LIBC_BIONIC
-#define CHOOSE_DYNAMIC_LINKER(G, U, B) \
-  CHOOSE_DYNAMIC_LINKER1 ("mbionic", "mglibc", "muclibc", B, G, U)
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("mbionic", "mglibc", "muclibc", "mmusl", B, G, U, M)
+#elif DEFAULT_LIBC == LIBC_MUSL
+#define CHOOSE_DYNAMIC_LINKER(G, U, B, M) \
+  CHOOSE_DYNAMIC_LINKER1 ("mmusl", "mglibc", "muclibc", "mbionic", M, G, U, B)
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif /* DEFAULT_LIBC */
@@ -85,16 +90,16 @@
 
 #define GNU_USER_DYNAMIC_LINKER						\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER,	\
-			 BIONIC_DYNAMIC_LINKER)
+			 BIONIC_DYNAMIC_LINKER, MUSL_DYNAMIC_LINKER)
 #define GNU_USER_DYNAMIC_LINKER32					\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32, \
-			 BIONIC_DYNAMIC_LINKER32)
+			 BIONIC_DYNAMIC_LINKER32, MUSL_DYNAMIC_LINKER32)
 #define GNU_USER_DYNAMIC_LINKER64					\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64, \
-			 BIONIC_DYNAMIC_LINKER64)
+			 BIONIC_DYNAMIC_LINKER64, MUSL_DYNAMIC_LINKER64)
 #define GNU_USER_DYNAMIC_LINKERX32					\
   CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKERX32, UCLIBC_DYNAMIC_LINKERX32, \
-			 BIONIC_DYNAMIC_LINKERX32)
+			 BIONIC_DYNAMIC_LINKERX32, MUSL_DYNAMIC_LINKERX32)
 
 /* Determine whether the entire c99 runtime
    is present in the runtime library.  */
diff --git a/gcc/config/linux.opt b/gcc/config/linux.opt
--- a/gcc/config/linux.opt
+++ b/gcc/config/linux.opt
@@ -30,3 +30,7 @@
 muclibc
 Target Report RejectNegative Var(linux_libc,LIBC_UCLIBC) Negative(mbionic)
 Use uClibc C library
+
+mmusl
+Target Report RejectNegative Var(linux_libc,LIBC_MUSL) Negative(mglibc)
+Use musl C library
diff --git a/gcc/config/mips/linux.h b/gcc/config/mips/linux.h
--- a/gcc/config/mips/linux.h
+++ b/gcc/config/mips/linux.h
@@ -19,3 +19,5 @@
 <http://www.gnu.org/licenses/>.  */
 
 #define GLIBC_DYNAMIC_LINKER "/lib/ld.so.1"
+
+#define MUSL_DYNAMIC_LINKER "/lib/ld-musl-mips.so.1"
diff --git a/gcc/config/rs6000/linux64.h b/gcc/config/rs6000/linux64.h
--- a/gcc/config/rs6000/linux64.h
+++ b/gcc/config/rs6000/linux64.h
@@ -362,17 +362,21 @@
 #define GLIBC_DYNAMIC_LINKER64 "/lib64/ld64.so.1"
 #define UCLIBC_DYNAMIC_LINKER32 "/lib/ld-uClibc.so.0"
 #define UCLIBC_DYNAMIC_LINKER64 "/lib/ld64-uClibc.so.0"
+#define MUSL_DYNAMIC_LINKER32 "/lib/ld-musl-powerpc.so.1"
+#define MUSL_DYNAMIC_LINKER64 "/lib/ld-musl-powerpc64.so.1"
 #if DEFAULT_LIBC == LIBC_UCLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{mglibc:" G ";:" U "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{mmusl:" M ";:" U "}}"
 #elif DEFAULT_LIBC == LIBC_GLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{muclibc:" U ";:" G "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{muclibc:" U ";:%{mmusl:" M ";:" G "}}"
+#elif DEFAULT_LIBC == LIBC_MUSL
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{muclibc:" U ";:" M "}}"
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif
 #define GNU_USER_DYNAMIC_LINKER32 \
-  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32)
+  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER32, UCLIBC_DYNAMIC_LINKER32, MUSL_DYNAMIC_LINKER32)
 #define GNU_USER_DYNAMIC_LINKER64 \
-  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64)
+  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER64, UCLIBC_DYNAMIC_LINKER64, MUSL_DYNAMIC_LINKER64)
 
 
 #define LINK_OS_LINUX_SPEC32 "-m elf32ppclinux %{!shared: %{!static: \
diff --git a/gcc/config/rs6000/sysv4.h b/gcc/config/rs6000/sysv4.h
--- a/gcc/config/rs6000/sysv4.h
+++ b/gcc/config/rs6000/sysv4.h
@@ -804,15 +804,18 @@
 
 #define GLIBC_DYNAMIC_LINKER "/lib/ld.so.1"
 #define UCLIBC_DYNAMIC_LINKER "/lib/ld-uClibc.so.0"
+#define MUSL_DYNAMIC_LINKER "/lib/ld-musl-powerpc.so.1"
 #if DEFAULT_LIBC == LIBC_UCLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{mglibc:" G ";:" U "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{mmusl:" M ";:" U "}}"
+#elif DEFAULT_LIBC == LIBC_MUSL
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{mglibc:" G ";:%{muclibc:" U ";:" M "}}"
 #elif !defined (DEFAULT_LIBC) || DEFAULT_LIBC == LIBC_GLIBC
-#define CHOOSE_DYNAMIC_LINKER(G, U) "%{muclibc:" U ";:" G "}"
+#define CHOOSE_DYNAMIC_LINKER(G, U, M) "%{muclibc:" U ";:%{mmusl:" M ";:" G "}}"
 #else
 #error "Unsupported DEFAULT_LIBC"
 #endif
 #define GNU_USER_DYNAMIC_LINKER \
-  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER)
+  CHOOSE_DYNAMIC_LINKER (GLIBC_DYNAMIC_LINKER, UCLIBC_DYNAMIC_LINKER, MUSL_DYNAMIC_LINKER)
 
 #define LINK_OS_LINUX_SPEC "-m elf32ppclinux %{!shared: %{!static: \
   %{rdynamic:-export-dynamic} \
diff --git a/gcc/ginclude/stddef.h b/gcc/ginclude/stddef.h
--- a/gcc/ginclude/stddef.h
+++ b/gcc/ginclude/stddef.h
@@ -184,6 +184,7 @@
 #ifndef _GCC_SIZE_T
 #ifndef _SIZET_
 #ifndef __size_t
+#ifndef __DEFINED_size_t /* musl */
 #define __size_t__	/* BeOS */
 #define __SIZE_T__	/* Cray Unicos/Mk */
 #define _SIZE_T
@@ -200,6 +201,7 @@
 #define ___int_size_t_h
 #define _GCC_SIZE_T
 #define _SIZET_
+#define __DEFINED_size_t /* musl */
 #if (defined (__FreeBSD__) && (__FreeBSD__ >= 5)) \
   || defined(__FreeBSD_kernel__)
 /* __size_t is a typedef on FreeBSD 5, must not trash it. */
@@ -215,6 +217,7 @@
 typedef long ssize_t;
 #endif /* __BEOS__ */
 #endif /* !(defined (__GNUG__) && defined (size_t)) */
+#endif /* __DEFINED_size_t */
 #endif /* __size_t */
 #endif /* _SIZET_ */
 #endif /* _GCC_SIZE_T */
diff --git a/libgomp/config/posix/time.c b/libgomp/config/posix/time.c
--- a/libgomp/config/posix/time.c
+++ b/libgomp/config/posix/time.c
@@ -28,6 +28,8 @@
    The following implementation uses the most simple POSIX routines.
    If present, POSIX 4 clocks should be used instead.  */
 
+#define _POSIX_C_SOURCE 199309L /* for clocks */
+
 #include "libgomp.h"
 #include <unistd.h>
 #if TIME_WITH_SYS_TIME
diff --git a/libitm/config/arm/hwcap.cc b/libitm/config/arm/hwcap.cc
--- a/libitm/config/arm/hwcap.cc
+++ b/libitm/config/arm/hwcap.cc
@@ -40,7 +40,11 @@
 
 #ifdef __linux__
 #include <unistd.h>
+#ifdef __GLIBC__
 #include <sys/fcntl.h>
+#else
+#include <fcntl.h>
+#endif
 #include <elf.h>
 
 static void __attribute__((constructor))
diff --git a/libitm/config/linux/x86/tls.h b/libitm/config/linux/x86/tls.h
--- a/libitm/config/linux/x86/tls.h
+++ b/libitm/config/linux/x86/tls.h
@@ -25,16 +25,19 @@
 #ifndef LIBITM_X86_TLS_H
 #define LIBITM_X86_TLS_H 1
 
-#if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 10)
+#if defined(__GLIBC_PREREQ)
+#if __GLIBC_PREREQ(2, 10)
 /* Use slots in the TCB head rather than __thread lookups.
    GLIBC has reserved words 10 through 13 for TM.  */
 #define HAVE_ARCH_GTM_THREAD 1
 #define HAVE_ARCH_GTM_THREAD_DISP 1
 #endif
+#endif
 
 #include "config/generic/tls.h"
 
-#if defined(__GLIBC_PREREQ) && __GLIBC_PREREQ(2, 10)
+#if defined(__GLIBC_PREREQ)
+#if __GLIBC_PREREQ(2, 10)
 namespace GTM HIDDEN {
 
 #ifdef __x86_64__
@@ -101,5 +104,6 @@
 
 } // namespace GTM
 #endif /* >= GLIBC 2.10 */
+#endif
 
 #endif // LIBITM_X86_TLS_H
diff --git a/libstdc++-v3/configure.host b/libstdc++-v3/configure.host
--- a/libstdc++-v3/configure.host
+++ b/libstdc++-v3/configure.host
@@ -243,6 +243,13 @@
     os_include_dir="os/bsd/freebsd"
     ;;
   gnu* | linux* | kfreebsd*-gnu | knetbsd*-gnu)
+    # check for musl by target
+    case "${host_os}" in
+      *-musl*)
+        os_include_dir="os/generic"
+        ;;
+      *)
+
     if [ "$uclibc" = "yes" ]; then
       os_include_dir="os/uclibc"
     elif [ "$bionic" = "yes" ]; then
@@ -251,6 +258,9 @@
       os_include_dir="os/gnu-linux"
     fi
     ;;
+
+    esac
+    ;;
   hpux*)
     os_include_dir="os/hpux"
     ;;
