diff --git a/lib/systems/examples.nix b/lib/systems/examples.nix
index f5562e28a09d..bd68ee9460e7 100644
--- a/lib/systems/examples.nix
+++ b/lib/systems/examples.nix
@@ -68,6 +68,14 @@ rec {
   musl64 = { config = "x86_64-unknown-linux-musl"; };
   musl32  = { config = "i686-unknown-linux-musl"; };
 
+  riscv = bits: {
+    config = "riscv${bits}-unknown-linux-gnu";
+    platform = platforms.riscv-multiplatform bits;
+  };
+  riscv64 = riscv "64";
+  riscv32 = riscv "32";
+
+
   #
   # Darwin
   #
diff --git a/lib/systems/platforms.nix b/lib/systems/platforms.nix
index 58a7afa7679d..3106c05dd5d2 100644
--- a/lib/systems/platforms.nix
+++ b/lib/systems/platforms.nix
@@ -541,6 +541,12 @@ rec {
     };
   };
 
+  riscv-multiplatform = bits: {
+    name = "riscv-multiplatform";
+    kernelArch = "riscv";
+    bfdEmulation = "elf${bits}lriscv";
+  };
+
   selectBySystem = system: {
       "i686-linux" = pc32;
       "x86_64-linux" = pc64;
diff --git a/pkgs/applications/virtualization/qemu/default.nix b/pkgs/applications/virtualization/qemu/default.nix
index 48a9296fa97d..694026d3bac2 100644
--- a/pkgs/applications/virtualization/qemu/default.nix
+++ b/pkgs/applications/virtualization/qemu/default.nix
@@ -61,7 +61,7 @@ stdenv.mkDerivation rec {
 
   enableParallelBuilding = true;
 
-  patches = [ ./no-etc-install.patch ]
+  patches = [ ./no-etc-install.patch ./statfs-flags.patch ]
     ++ optional nixosTestRunner ./force-uid0-on-9p.patch
     ++ optional pulseSupport ./fix-hda-recording.patch;
 
diff --git a/pkgs/applications/virtualization/qemu/statfs-flags.patch b/pkgs/applications/virtualization/qemu/statfs-flags.patch
new file mode 100644
index 000000000000..c0f0162aacc9
--- /dev/null
+++ b/pkgs/applications/virtualization/qemu/statfs-flags.patch
@@ -0,0 +1,200 @@
+commit d3282d2512774dc5027c98930a3852b2b6e8407a
+Author: Shea Levy <shea@shealevy.com>
+Date:   Sun Feb 18 13:50:11 2018 -0500
+
+    linux-user: Support f_flags in statfs when available.
+    
+    Signed-off-by: Shea Levy <shea@shealevy.com>
+
+diff --git a/configure b/configure
+index 913e14839d..52fe2bf941 100755
+--- a/configure
++++ b/configure
+@@ -5303,6 +5303,22 @@ if compile_prog "" "" ; then
+     have_utmpx=yes
+ fi
+ 
++##########################################
++# Check for newer fields of struct statfs on Linux
++
++if test "$linux_user" = "yes"; then
++  cat > $TMPC <<EOF
++#include <sys/vfs.h>
++
++int main(void) {
++  struct statfs fs;
++  fs.f_flags = 0;
++}
++EOF
++  if compile_object ; then
++      have_statfs_flags=yes
++  fi
++fi
+ ##########################################
+ # checks for sanitizers
+ 
+@@ -6518,6 +6534,10 @@ if test "$have_utmpx" = "yes" ; then
+   echo "HAVE_UTMPX=y" >> $config_host_mak
+ fi
+ 
++if test "$have_statfs_flags" = "yes" ; then
++  echo "HAVE_STATFS_FLAGS=y" >> $config_host_mak
++fi
++
+ if test "$ivshmem" = "yes" ; then
+   echo "CONFIG_IVSHMEM=y" >> $config_host_mak
+ fi
+diff --git a/linux-user/syscall.c b/linux-user/syscall.c
+index 82b35a6bdf..77481eca2c 100644
+--- a/linux-user/syscall.c
++++ b/linux-user/syscall.c
+@@ -9534,6 +9534,9 @@ abi_long do_syscall(void *cpu_env, int num, abi_long arg1,
+             __put_user(stfs.f_fsid.__val[1], &target_stfs->f_fsid.val[1]);
+             __put_user(stfs.f_namelen, &target_stfs->f_namelen);
+             __put_user(stfs.f_frsize, &target_stfs->f_frsize);
++#ifdef HAVE_STATFS_FLAGS
++            __put_user(stfs.f_flags, &target_stfs->f_flags);
++#endif
+             memset(target_stfs->f_spare, 0, sizeof(target_stfs->f_spare));
+             unlock_user_struct(target_stfs, arg2, 1);
+         }
+diff --git a/linux-user/syscall_defs.h b/linux-user/syscall_defs.h
+index a35c52a60a..9f90451caf 100644
+--- a/linux-user/syscall_defs.h
++++ b/linux-user/syscall_defs.h
+@@ -362,7 +362,14 @@ struct kernel_statfs {
+ 	int f_ffree;
+         kernel_fsid_t f_fsid;
+ 	int f_namelen;
++#ifdef HAVE_STATFS_FLAGS
++	int f_frsize;
++	int f_flags;
++	int f_spare[4];
++#else
+ 	int f_spare[6];
++#endif
++
+ };
+ 
+ struct target_dirent {
+@@ -2223,7 +2230,13 @@ struct target_statfs {
+ 	/* Linux specials */
+ 	target_fsid_t		f_fsid;
+ 	int32_t			f_namelen;
++#ifdef HAVE_STATFS_FLAGS
++	int32_t			f_frsize;
++	int32_t			f_flags;
++	int32_t			f_spare[4];
++#else
+ 	int32_t			f_spare[6];
++#endif
+ };
+ #else
+ struct target_statfs {
+@@ -2239,7 +2252,13 @@ struct target_statfs {
+ 	/* Linux specials */
+ 	target_fsid_t		f_fsid;
+ 	abi_long		f_namelen;
++#ifdef HAVE_STATFS_FLAGS
++	abi_long		f_frsize;
++	abi_long		f_flags;
++	abi_long		f_spare[4];
++#else
+ 	abi_long		f_spare[6];
++#endif
+ };
+ #endif
+ 
+@@ -2255,7 +2274,13 @@ struct target_statfs64 {
+ 	uint64_t	f_bavail;
+ 	target_fsid_t	f_fsid;
+ 	uint32_t	f_namelen;
++#ifdef HAVE_STATFS_FLAGS
++	uint32_t	f_frsize;
++	uint32_t	f_flags;
++	uint32_t	f_spare[4];
++#else
+ 	uint32_t	f_spare[6];
++#endif
+ };
+ #elif (defined(TARGET_PPC64) || defined(TARGET_X86_64) || \
+        defined(TARGET_SPARC64) || defined(TARGET_AARCH64)) && \
+@@ -2271,7 +2296,12 @@ struct target_statfs {
+ 	target_fsid_t f_fsid;
+ 	abi_long f_namelen;
+ 	abi_long f_frsize;
++#ifdef HAVE_STATFS_FLAGS
++	abi_long f_flags;
++	abi_long f_spare[4];
++#else
+ 	abi_long f_spare[5];
++#endif
+ };
+ 
+ struct target_statfs64 {
+@@ -2285,7 +2315,12 @@ struct target_statfs64 {
+ 	target_fsid_t f_fsid;
+ 	abi_long f_namelen;
+ 	abi_long f_frsize;
++#ifdef HAVE_STATFS_FLAGS
++	abi_long f_flags;
++	abi_long f_spare[4];
++#else
+ 	abi_long f_spare[5];
++#endif
+ };
+ #elif defined(TARGET_S390X)
+ struct target_statfs {
+@@ -2299,7 +2334,13 @@ struct target_statfs {
+     kernel_fsid_t f_fsid;
+     int32_t  f_namelen;
+     int32_t  f_frsize;
++#ifdef HAVE_STATFS_FLAGS
++    int32_t  f_flags;
++    int32_t  f_spare[4];
++#else
+     int32_t  f_spare[5];
++#endif
++
+ };
+ 
+ struct target_statfs64 {
+@@ -2313,7 +2354,12 @@ struct target_statfs64 {
+     kernel_fsid_t f_fsid;
+     int32_t  f_namelen;
+     int32_t  f_frsize;
++#ifdef HAVE_STATFS_FLAGS
++    int32_t  f_flags;
++    int32_t  f_spare[4];
++#else
+     int32_t  f_spare[5];
++#endif
+ };
+ #else
+ struct target_statfs {
+@@ -2327,7 +2373,12 @@ struct target_statfs {
+ 	target_fsid_t f_fsid;
+ 	uint32_t f_namelen;
+ 	uint32_t f_frsize;
++#ifdef HAVE_STATFS_FLAGS
++	uint32_t f_flags;
++	uint32_t f_spare[4];
++#else
+ 	uint32_t f_spare[5];
++#endif
+ };
+ 
+ struct target_statfs64 {
+@@ -2341,7 +2392,12 @@ struct target_statfs64 {
+ 	target_fsid_t f_fsid;
+         uint32_t f_namelen;
+ 	uint32_t f_frsize;
++#ifdef HAVE_STATFS_FLAGS
++	uint32_t f_flags;
++	uint32_t f_spare[4];
++#else
+ 	uint32_t f_spare[5];
++#endif
+ };
+ #endif
+ 
diff --git a/pkgs/development/compilers/swift/default.nix b/pkgs/development/compilers/swift/default.nix
index 937977b0a97d..360f96e12427 100644
--- a/pkgs/development/compilers/swift/default.nix
+++ b/pkgs/development/compilers/swift/default.nix
@@ -12,7 +12,6 @@
 , swig
 , bash
 , libxml2
-, llvm
 , clang
 , python
 , ncurses
@@ -28,13 +27,17 @@
 , git
 , libgit2
 , fetchFromGitHub
+, fetchpatch
 , paxctl
 , findutils
+, makeWrapper
+, gnumake
+, file
 #, systemtap
 }:
 
 let
-  v_major = "3.1.1";
+  v_major = "4.0.3";
   version = "${v_major}-RELEASE";
   version_friendly = "${v_major}";
 
@@ -47,53 +50,53 @@ let
       name = "${repo}-${version}-src";
     };
 
-sources = {
+  sources = {
     # FYI: SourceKit probably would work but currently requires building everything twice
     # For more inforation, see: https://github.com/apple/swift/pull/3594#issuecomment-234169759
     clang = fetch {
       repo = "swift-clang";
-      sha256 = "1gmdgr8jph87nya8cgdl7iwrggbji2sag996m27hkbszw4nxy8sd";
+      sha256 = "0zm624iwiprk3c3nzqf4p1fd9zqic4yi3jv51cw3249ax4x6vy10";
     };
     llvm = fetch {
       repo = "swift-llvm";
-      sha256 = "0nwd7cp6mbj7f6a2rx8123n7ygs8406hsx7hp7ybagww6v75bwzi";
+      sha256 = "11vw6461c0cdvwm1wna1a5709fjj14hzp6br6jg94p4f6jp3yv4d";
     };
     compilerrt = fetch {
       repo = "swift-compiler-rt";
-      sha256 = "1gjcr6g3ffs3nhf4a84iwg4flbd7rqcf9rvvclwyq96msa3mj950";
+      sha256 = "1hj4qaj4c9n2wzg2cvarbyl0n708zd1dlw4zkzq07fjxxqs36nfa";
     };
     cmark = fetch {
       repo = "swift-cmark";
-      sha256 = "0qf2f3zd8lndkfbxbz6vkznzz8rvq5gigijh7pgmfx9fi4zcssqx";
+      sha256 = "1nmxp0fj749sgar682c5nsj7zxxigqwg973baxj2r656a7ybh325";
     };
     lldb = fetch {
       repo = "swift-lldb";
-      sha256 = "17n4whpf3wxw9zaayiq21gk9q3547qxi4rvxld2hybh0k7a1bj5c";
+      sha256 = "0yk5qg85008vcn63vn2jpn5ls9pdhda222p2w1cfkrj27k5k8vqr";
     };
     llbuild = fetch {
       repo = "swift-llbuild";
-      sha256 = "1l3hnb2s01jby91k1ipbc3bhszq14vyx5pzdhf2chld1yhpg420d";
+      sha256 = "0jffw6z1s6ck1i05brw59x6vsg7zrxbz5n2wz72fj29rh3nppc7a";
     };
     pm = fetch {
       repo = "swift-package-manager";
-      sha256 = "1ayy5vk3mjk354pg9bf68wvnaj3jymx23w0qnlw1jxz256ff8fwi";
+      sha256 = "0xj070b8fii7ijfsnyq4fxgv6569vdrg0yippi85h2p1l7s9aagh";
     };
     xctest = fetch {
       repo = "swift-corelibs-xctest";
-      sha256 = "0cj5y7wanllfldag08ci567x12aw793c79afckpbsiaxmwy4xhnm";
+      sha256 = "0l355wq8zfwrpv044xf4smjwbm0bmib360748n8cwls3vkr9l2yv";
     };
     foundation = fetch {
       repo = "swift-corelibs-foundation";
-      sha256 = "1d1ldk7ckqn4mhmdhsx2zrmsd6jfxzgdywn2pki7limk979hcwjc";
+      sha256 = "0s7yc5gsbd96a4bs8c6q24dyfjm4xhcr2nzhl2ics8dmi60j15s4";
     };
     libdispatch = fetch {
       repo = "swift-corelibs-libdispatch";
-      sha256 = "0ckjg41fjak06i532azhryckjq64fkxzsal4svf5v4s8n9mkq2sg";
+      sha256 = "0x8zzq3shhvmhq4sbhaaa0ddiv3nw347pz6ayym6jyzq7j9n15ia";
       fetchSubmodules = true;
     };
     swift = fetch {
       repo = "swift";
-      sha256 = "0879jlv37lmxc1apzi53xn033y72548i86r7fzwr0g52124q5gry";
+      sha256 = "0a1gq0k5701i418f0qi7kywv16q7vh4a4wp0f6fpyv4sjkq27msx";
     };
   };
 
@@ -119,6 +122,9 @@ sources = {
   ];
 
   builder = ''
+    # gcc-6.4.0/include/c++/6.4.0/cstdlib:75:15: fatal error: 'stdlib.h' file not found
+    NIX_CFLAGS_COMPILE="$( echo ${clang.default_cxx_stdlib_compile} ) $NIX_CFLAGS_COMPILE"
+
     $SWIFT_SOURCE_ROOT/swift/utils/build-script \
       --preset=buildbot_linux \
       installable_package=$INSTALLABLE_PACKAGE \
@@ -126,6 +132,20 @@ sources = {
       install_destdir=$SWIFT_INSTALL_DIR \
       extra_cmake_options="${stdenv.lib.concatStringsSep "," cmakeFlags}"'';
 
+  # from llvm/4/llvm.nix
+  sigaltstackPatch = fetchpatch {
+    name = "sigaltstack.patch"; # for glibc-2.26
+    url = https://github.com/llvm-mirror/compiler-rt/commit/8a5e425a68d.diff;
+    sha256 = "0h4y5vl74qaa7dl54b1fcyqalvlpd8zban2d1jxfkxpzyi7m8ifi";
+  };
+
+  # https://bugs.swift.org/browse/SR-6409
+  sigunusedPatch = fetchpatch {
+    name = "sigunused.patch";
+    url = "https://github.com/apple/swift-llbuild/commit/303a89bc6da606c115560921a452686aa0655f5e.diff";
+    sha256 = "04sw7ym1grzggj1v3xrzr2ljxz8rf9rnn9n5fg1xjbwlrdagkc7m";
+  };
+
 in
 stdenv.mkDerivation rec {
   name = "swift-${version_friendly}";
@@ -145,6 +165,8 @@ stdenv.mkDerivation rec {
     rsync
     which
     findutils
+    makeWrapper
+    gnumake
   ] ++ stdenv.lib.optional stdenv.needsPax paxctl;
 
   # TODO: Revisit what's propagated and how
@@ -198,6 +220,14 @@ stdenv.mkDerivation rec {
     # Just patch all the things for now, we can focus this later
     patchShebangs $SWIFT_SOURCE_ROOT
 
+    # TODO eliminate use of env.
+    find -type f -print0 | xargs -0 sed -i \
+      -e 's|/usr/bin/env|${coreutils}/bin/env|g' \
+      -e 's|/usr/bin/make|${gnumake}/bin/make|g' \
+      -e 's|/bin/mkdir|${coreutils}/bin/mkdir|g' \
+      -e 's|/bin/cp|${coreutils}/bin/cp|g' \
+      -e 's|/usr/bin/file|${file}/bin/file|g'
+
     substituteInPlace swift/stdlib/public/Platform/CMakeLists.txt \
       --replace '/usr/include' "${stdenv.cc.libc.dev}/include"
     substituteInPlace swift/utils/build-script-impl \
@@ -209,6 +239,13 @@ stdenv.mkDerivation rec {
     patch -p1 -d swift -i ${./patches/0002-build-presets-linux-allow-custom-install-prefix.patch}
     patch -p1 -d swift -i ${./patches/0003-build-presets-linux-disable-tests.patch}
     patch -p1 -d swift -i ${./patches/0004-build-presets-linux-plumb-extra-cmake-options.patch}
+    # https://sourceware.org/glibc/wiki/Release/2.26#Removal_of_.27xlocale.h.27
+    patch -p1 -i ${./patches/remove_xlocale.patch}
+    # https://bugs.swift.org/browse/SR-4633
+    patch -p1 -d swift -i ${./patches/icu59.patch}
+
+    # https://bugs.swift.org/browse/SR-5779
+    sed -i -e 's|"-latomic"|"-Wl,-rpath,${clang.cc.gcc.lib}/lib" "-L${clang.cc.gcc.lib}/lib" "-latomic"|' swift/cmake/modules/AddSwift.cmake
 
     substituteInPlace clang/lib/Driver/ToolChains.cpp \
       --replace '  addPathIfExists(D, SysRoot + "/usr/lib", Paths);' \
@@ -217,21 +254,21 @@ stdenv.mkDerivation rec {
 
     # Workaround hardcoded dep on "libcurses" (vs "libncurses"):
     sed -i 's,curses,ncurses,' llbuild/*/*/CMakeLists.txt
-    substituteInPlace llbuild/tests/BuildSystem/Build/basic.llbuild \
-      --replace /usr/bin/env $(type -p env)
 
     # This test fails on one of my machines, not sure why.
     # Disabling for now. 
     rm llbuild/tests/Examples/buildsystem-capi.llbuild
 
-    substituteInPlace swift-corelibs-foundation/lib/script.py \
-      --replace /bin/cp $(type -p cp)
-
     PREFIX=''${out/#\/}
     substituteInPlace swift-corelibs-xctest/build_script.py \
       --replace usr "$PREFIX"
     substituteInPlace swiftpm/Utilities/bootstrap \
       --replace "usr" "$PREFIX"
+  '' + stdenv.lib.optionalString (stdenv ? glibc) ''
+    patch -p1 -d compiler-rt -i ${sigaltstackPatch}
+    patch -p1 -d compiler-rt -i ${./patches/sigaltstack.patch}
+    patch -p1 -d llbuild -i ${sigunusedPatch}
+    patch -p1 -i ${./patches/sigunused.patch}
   '';
 
   doCheck = false;
@@ -251,6 +288,10 @@ stdenv.mkDerivation rec {
     # TODO: Use wrappers to get these on the PATH for swift tools, instead
     ln -s ${clang}/bin/* $out/bin/
     ln -s ${targetPackages.stdenv.cc.bintools}/bin/ar $out/bin/ar
+
+    wrapProgram $out/bin/swift \
+      --suffix C_INCLUDE_PATH : $out/lib/swift/clang/include \
+      --suffix CPLUS_INCLUDE_PATH : $out/lib/swift/clang/include
   '';
 
   # Hack to avoid TMPDIR in RPATHs.
@@ -263,7 +304,6 @@ stdenv.mkDerivation rec {
     license = licenses.asl20;
     # Swift doesn't support 32bit Linux, unknown on other platforms.
     platforms = [ "x86_64-linux" ];
-    broken = true;
   };
 }
 
diff --git a/pkgs/development/compilers/swift/patches/0002-build-presets-linux-allow-custom-install-prefix.patch b/pkgs/development/compilers/swift/patches/0002-build-presets-linux-allow-custom-install-prefix.patch
index 0e18e8812a84..66723f1cdf39 100644
--- a/pkgs/development/compilers/swift/patches/0002-build-presets-linux-allow-custom-install-prefix.patch
+++ b/pkgs/development/compilers/swift/patches/0002-build-presets-linux-allow-custom-install-prefix.patch
@@ -11,13 +11,13 @@ diff --git a/utils/build-presets.ini b/utils/build-presets.ini
 index e6b0af3581..1095cbaab7 100644
 --- a/utils/build-presets.ini
 +++ b/utils/build-presets.ini
-@@ -692,7 +692,7 @@ install-lldb
+@@ -708,7 +708,7 @@ install-lldb
  install-llbuild
  install-swiftpm
  install-xctest
 -install-prefix=/usr
 +install-prefix=%(install_prefix)s
- swift-install-components=autolink-driver;compiler;clang-builtin-headers;stdlib;swift-remote-mirror;sdk-overlay;license
+ swift-install-components=autolink-driver;compiler;clang-builtin-headers;stdlib;swift-remote-mirror;sdk-overlay;license;sourcekit-inproc
  build-swift-static-stdlib
  build-swift-static-sdk-overlay
 -- 
diff --git a/pkgs/development/compilers/swift/patches/icu59.patch b/pkgs/development/compilers/swift/patches/icu59.patch
new file mode 100644
index 000000000000..26337814cafa
--- /dev/null
+++ b/pkgs/development/compilers/swift/patches/icu59.patch
@@ -0,0 +1,113 @@
+--- a/stdlib/public/stubs/UnicodeNormalization.cpp
++++ b/stdlib/public/stubs/UnicodeNormalization.cpp
+@@ -86,11 +86,8 @@ ASCIICollation() {
+     for (unsigned char c = 0; c < 128; ++c) {
+       UErrorCode ErrorCode = U_ZERO_ERROR;
+       intptr_t NumCollationElts = 0;
+-#if defined(__CYGWIN__) || defined(_MSC_VER)
+       UChar Buffer[1];
+-#else
+-      uint16_t Buffer[1];
+-#endif
++
+       Buffer[0] = c;
+ 
+       UCollationElements *CollationIterator =
+@@ -127,18 +124,9 @@ swift::_swift_stdlib_unicode_compare_utf16_utf16(const uint16_t *LeftString,
+                                                  int32_t LeftLength,
+                                                  const uint16_t *RightString,
+                                                  int32_t RightLength) {
+-#if defined(__CYGWIN__) || defined(_MSC_VER)
+-  // ICU UChar type is platform dependent. In Cygwin, it is defined
+-  // as wchar_t which size is 2. It seems that the underlying binary
+-  // representation is same with swift utf16 representation.
+   return ucol_strcoll(GetRootCollator(),
+     reinterpret_cast<const UChar *>(LeftString), LeftLength,
+     reinterpret_cast<const UChar *>(RightString), RightLength);
+-#else
+-  return ucol_strcoll(GetRootCollator(),
+-    LeftString, LeftLength,
+-    RightString, RightLength);
+-#endif
+ }
+ 
+ /// Compares the strings via the Unicode Collation Algorithm on the root locale.
+@@ -156,12 +144,8 @@ swift::_swift_stdlib_unicode_compare_utf8_utf16(const unsigned char *LeftString,
+   UErrorCode ErrorCode = U_ZERO_ERROR;
+ 
+   uiter_setUTF8(&LeftIterator, reinterpret_cast<const char *>(LeftString), LeftLength);
+-#if defined(__CYGWIN__) || defined(_MSC_VER)
+   uiter_setString(&RightIterator, reinterpret_cast<const UChar *>(RightString),
+                   RightLength);
+-#else
+-  uiter_setString(&RightIterator, RightString, RightLength);
+-#endif
+ 
+   uint32_t Diff = ucol_strcollIter(GetRootCollator(),
+     &LeftIterator, &RightIterator, &ErrorCode);
+@@ -199,14 +183,10 @@ swift::_swift_stdlib_unicode_compare_utf8_utf8(const unsigned char *LeftString,
+ void *swift::_swift_stdlib_unicodeCollationIterator_create(
+     const __swift_uint16_t *Str, __swift_uint32_t Length) {
+   UErrorCode ErrorCode = U_ZERO_ERROR;
+-#if defined(__CYGWIN__) || defined(_MSC_VER)
+   UCollationElements *CollationIterator = ucol_openElements(
+     GetRootCollator(), reinterpret_cast<const UChar *>(Str), Length,
+     &ErrorCode);
+-#else
+-  UCollationElements *CollationIterator = ucol_openElements(
+-    GetRootCollator(), Str, Length, &ErrorCode);
+-#endif
++
+   if (U_FAILURE(ErrorCode)) {
+     swift::crash("_swift_stdlib_unicodeCollationIterator_create: ucol_openElements() failed.");
+   }
+@@ -244,17 +224,12 @@ swift::_swift_stdlib_unicode_strToUpper(uint16_t *Destination,
+                                         const uint16_t *Source,
+                                         int32_t SourceLength) {
+   UErrorCode ErrorCode = U_ZERO_ERROR;
+-#if defined(__CYGWIN__) || defined(_MSC_VER)
+   uint32_t OutputLength = u_strToUpper(reinterpret_cast<UChar *>(Destination),
+                                        DestinationCapacity,
+                                        reinterpret_cast<const UChar *>(Source),
+                                        SourceLength,
+                                        "", &ErrorCode);
+-#else
+-  uint32_t OutputLength = u_strToUpper(Destination, DestinationCapacity,
+-                                       Source, SourceLength,
+-                                       "", &ErrorCode);
+-#endif
++
+   if (U_FAILURE(ErrorCode) && ErrorCode != U_BUFFER_OVERFLOW_ERROR) {
+     swift::crash("u_strToUpper: Unexpected error uppercasing unicode string.");
+   }
+@@ -271,17 +246,12 @@ swift::_swift_stdlib_unicode_strToLower(uint16_t *Destination,
+                                         const uint16_t *Source,
+                                         int32_t SourceLength) {
+   UErrorCode ErrorCode = U_ZERO_ERROR;
+-#if defined(__CYGWIN__) || defined(_MSC_VER)
+   uint32_t OutputLength = u_strToLower(reinterpret_cast<UChar *>(Destination),
+                                        DestinationCapacity,
+                                        reinterpret_cast<const UChar *>(Source),
+                                        SourceLength,
+                                        "", &ErrorCode);
+-#else
+-  uint32_t OutputLength = u_strToLower(Destination, DestinationCapacity,
+-                                       Source, SourceLength,
+-                                       "", &ErrorCode);
+-#endif
++
+   if (U_FAILURE(ErrorCode) && ErrorCode != U_BUFFER_OVERFLOW_ERROR) {
+     swift::crash("u_strToLower: Unexpected error lowercasing unicode string.");
+   }
+@@ -300,9 +300,9 @@
+ 
+ swift::__swift_stdlib_UBreakIterator *swift::__swift_stdlib_ubrk_open(
+     swift::__swift_stdlib_UBreakIteratorType type, const char *locale,
+-    const UChar *text, int32_t textLength, __swift_stdlib_UErrorCode *status) {
++    const __swift_stdlib_UChar * text, __swift_int32_t textLength, __swift_stdlib_UErrorCode *status) {
+   return ptr_cast<swift::__swift_stdlib_UBreakIterator>(
+-      ubrk_open(static_cast<UBreakIteratorType>(type), locale, text, textLength,
++      ubrk_open(static_cast<UBreakIteratorType>(type), locale, reinterpret_cast<const UChar *>(text), textLength,
+                 ptr_cast<UErrorCode>(status)));
+ }
+ 
diff --git a/pkgs/development/compilers/swift/patches/remove_xlocale.patch b/pkgs/development/compilers/swift/patches/remove_xlocale.patch
new file mode 100644
index 000000000000..8ef7e3916962
--- /dev/null
+++ b/pkgs/development/compilers/swift/patches/remove_xlocale.patch
@@ -0,0 +1,54 @@
+--- a/swift/stdlib/public/SDK/os/os_trace_blob.c
++++ b/swift/stdlib/public/SDK/os/os_trace_blob.c
+@@ -14,7 +14,6 @@
+ #include <dispatch/dispatch.h>
+ #include <os/base.h>
+ #include <os/log.h>
+-#include <xlocale.h>
+ #include "os_trace_blob.h"
+ 
+ OS_NOINLINE
+
+--- a/swift/stdlib/public/stubs/Stubs.cpp
++++ b/swift/stdlib/public/stubs/Stubs.cpp
+@@ -61,7 +61,6 @@
+ #define strtof_l swift_strtof_l
+ #define strtold_l swift_strtold_l
+ #else
+-#include <xlocale.h>
+ #endif
+ #include <limits>
+ #include "llvm/ADT/StringExtras.h"
+
+--- a/swift-corelibs-foundation/CoreFoundation/String.subproj/CFStringDefaultEncoding.h
++++ b/swift-corelibs-foundation/CoreFoundation/String.subproj/CFStringDefaultEncoding.h
+@@ -20,7 +20,6 @@
+ #include <unistd.h>
+ #include <string.h>
+ #include <stdio.h>
+-#include <xlocale.h>
+ 
+ CF_EXTERN_C_BEGIN
+ 
+
+--- a/swift-corelibs-foundation/CoreFoundation/String.subproj/CFStringEncodings.c
++++ b/swift-corelibs-foundation/CoreFoundation/String.subproj/CFStringEncodings.c
+@@ -24,7 +24,6 @@
+ #include <unistd.h>
+ #include <string.h>
+ #include <stdio.h>
+-#include <xlocale.h>
+ #include <CoreFoundation/CFStringDefaultEncoding.h>
+ #endif
+ 
+
+--- a/swift-corelibs-foundation/CoreFoundation/Base.subproj/CFInternal.h
++++ b/swift-corelibs-foundation/CoreFoundation/Base.subproj/CFInternal.h
+@@ -95,7 +95,6 @@
+ #if DEPLOYMENT_TARGET_MACOSX || DEPLOYMENT_TARGET_EMBEDDED || DEPLOYMENT_TARGET_EMBEDDED_MINI || DEPLOYMENT_TARGET_LINUX || DEPLOYMENT_TARGET_FREEBSD
+ #if TARGET_OS_CYGWIN
+ #else
+-#include <xlocale.h>
+ #endif
+ #include <unistd.h>
+ #include <sys/time.h>
diff --git a/pkgs/development/compilers/swift/patches/sigaltstack.patch b/pkgs/development/compilers/swift/patches/sigaltstack.patch
new file mode 100644
index 000000000000..c529fa3777b3
--- /dev/null
+++ b/pkgs/development/compilers/swift/patches/sigaltstack.patch
@@ -0,0 +1,11 @@
+--- a/lib/esan/esan_sideline_linux.cpp
++++ b/lib/esan/esan_sideline_linux.cpp
+@@ -70,7 +70,7 @@ int SidelineThread::runSideline(void *Arg) {
+ 
+   // Set up a signal handler on an alternate stack for safety.
+   InternalScopedBuffer<char> StackMap(SigAltStackSize);
+-  struct sigaltstack SigAltStack;
++  stack_t SigAltStack;
+   SigAltStack.ss_sp = StackMap.data();
+   SigAltStack.ss_size = SigAltStackSize;
+   SigAltStack.ss_flags = 0;
diff --git a/pkgs/development/compilers/swift/patches/sigunused.patch b/pkgs/development/compilers/swift/patches/sigunused.patch
new file mode 100644
index 000000000000..2701d1a3ae25
--- /dev/null
+++ b/pkgs/development/compilers/swift/patches/sigunused.patch
@@ -0,0 +1,11 @@
+--- a/swiftpm/Sources/Basic/Process.swift
++++ b/swiftpm/Sources/Basic/Process.swift
+@@ -258,7 +258,7 @@ public func launch() throws {
+         // modify, so we have to take care about the set we use.
+         var mostSignals = sigset_t()
+         sigemptyset(&mostSignals)
+-        for i in 1 ..< SIGUNUSED {
++        for i in 1 ..< SIGSYS {
+             if i == SIGKILL || i == SIGSTOP {
+                 continue
+             }
diff --git a/pkgs/development/libraries/boehm-gc/default.nix b/pkgs/development/libraries/boehm-gc/default.nix
index c1bcb46bae6e..d4e91deb7449 100644
--- a/pkgs/development/libraries/boehm-gc/default.nix
+++ b/pkgs/development/libraries/boehm-gc/default.nix
@@ -27,7 +27,9 @@ stdenv.mkDerivation rec {
   patches = [ (fetchpatch {
     url = "https://raw.githubusercontent.com/gentoo/musl/85b6a600996bdd71162b357e9ba93d8559342432/dev-libs/boehm-gc/files/boehm-gc-7.6.0-sys_select.patch";
     sha256 = "1gydwlklvci30f5dpp5ccw2p2qpph5y41r55wx9idamjlq66fbb3";
-  }) ];
+  }) ] ++
+    # https://github.com/ivmai/bdwgc/pull/208
+    lib.optional hostPlatform.isRiscV ./riscv.patch;
 
   configureFlags =
     [ "--enable-cplusplus" ]
diff --git a/pkgs/development/libraries/boehm-gc/riscv.patch b/pkgs/development/libraries/boehm-gc/riscv.patch
new file mode 100644
index 000000000000..249137d0a0dc
--- /dev/null
+++ b/pkgs/development/libraries/boehm-gc/riscv.patch
@@ -0,0 +1,53 @@
+diff --git a/include/private/gcconfig.h b/include/private/gcconfig.h
+index a8e55dd2..439cc88d 100644
+--- a/include/private/gcconfig.h
++++ b/include/private/gcconfig.h
+@@ -650,6 +650,15 @@
+ #   endif
+ #   define mach_type_known
+ # endif
++# if defined(__riscv) && defined(LINUX)
++#   if __riscv_xlen == 32
++#     define RISCV32
++#     define mach_type_known
++#   elif __riscv_xlen == 64
++#     define RISCV64
++#     define mach_type_known
++#   endif
++# endif
+ 
+ # if defined(SN_TARGET_PSP2)
+ #   define mach_type_known
+@@ -2970,6 +2979,32 @@
+ #   endif
+ # endif
+ 
++# ifdef RISCV32
++#   define CPP_WORDSZ 32
++#   define MACH_TYPE "RISC-V 32"
++#   define ALIGNMENT 4
++#   ifdef LINUX
++#     define OS_TYPE "LINUX"
++      extern int __data_start[];
++#     define DATASTART ((ptr_t)__data_start)
++#     define LINUX_STACKBOTTOM
++#     define DYNAMIC_LOADING
++#   endif
++# endif
++
++# ifdef RISCV64
++#   define CPP_WORDSZ 64
++#   define MACH_TYPE "RISC-V 64"
++#   define ALIGNMENT 8
++#   ifdef LINUX
++#     define OS_TYPE "LINUX"
++      extern int __data_start[];
++#     define DATASTART ((ptr_t)__data_start)
++#     define LINUX_STACKBOTTOM
++#     define DYNAMIC_LOADING
++#   endif
++# endif
++
+ #if defined(__GLIBC__) && !defined(DONT_USE_LIBC_PRIVATES)
+   /* Use glibc's stack-end marker. */
+ # define USE_LIBC_PRIVATES
diff --git a/pkgs/development/libraries/glibc/common-2.27.nix b/pkgs/development/libraries/glibc/common-2.27.nix
index d493feb35fa8..6c443ebbb932 100644
--- a/pkgs/development/libraries/glibc/common-2.27.nix
+++ b/pkgs/development/libraries/glibc/common-2.27.nix
@@ -192,6 +192,8 @@ stdenv.mkDerivation ({
     maintainers = [ lib.maintainers.eelco ];
     platforms = lib.platforms.linux;
   } // meta;
+
+  passthru = { inherit version; };
 }
 
 // lib.optionalAttrs (cross != null) {
diff --git a/pkgs/development/libraries/libatomic_ops/default.nix b/pkgs/development/libraries/libatomic_ops/default.nix
index 3aae754be405..714e9361440c 100644
--- a/pkgs/development/libraries/libatomic_ops/default.nix
+++ b/pkgs/development/libraries/libatomic_ops/default.nix
@@ -1,4 +1,4 @@
-{ stdenv, fetchurl, autoconf, automake, libtool }:
+{ stdenv, fetchurl, autoconf, automake, libtool, hostPlatform }:
 
 stdenv.mkDerivation rec {
   name = "libatomic_ops-${version}";
@@ -12,6 +12,9 @@ stdenv.mkDerivation rec {
     sha256 ="1rif2hjscq5mh639nsnjhb90c01gnmy1sbmj6x6hsn1xmpnj95r1";
   };
 
+  # https://github.com/ivmai/libatomic_ops/pull/32
+  patches = if hostPlatform.isRiscV then [ ./riscv.patch ] else null;
+
   nativeBuildInputs = stdenv.lib.optionals stdenv.isCygwin [ autoconf automake libtool ];
 
   preConfigure = stdenv.lib.optionalString stdenv.isCygwin ''
diff --git a/pkgs/development/libraries/libatomic_ops/riscv.patch b/pkgs/development/libraries/libatomic_ops/riscv.patch
new file mode 100644
index 000000000000..27f2408c34c6
--- /dev/null
+++ b/pkgs/development/libraries/libatomic_ops/riscv.patch
@@ -0,0 +1,40 @@
+diff -Naur libatomic_ops-7.6.2-orig/src/atomic_ops/sysdeps/gcc/riscv.h libatomic_ops-7.6.2/src/atomic_ops/sysdeps/gcc/riscv.h
+--- libatomic_ops-7.6.2-orig/src/atomic_ops/sysdeps/gcc/riscv.h	1969-12-31 19:00:00.000000000 -0500
++++ libatomic_ops-7.6.2/src/atomic_ops/sysdeps/gcc/riscv.h	2018-02-18 00:48:53.581721375 -0500
+@@ -0,0 +1 @@
++#include "generic.h"
+diff -Naur libatomic_ops-7.6.2-orig/src/atomic_ops.h libatomic_ops-7.6.2/src/atomic_ops.h
+--- libatomic_ops-7.6.2-orig/src/atomic_ops.h	2017-12-24 03:31:12.000000000 -0500
++++ libatomic_ops-7.6.2/src/atomic_ops.h	2018-02-18 00:48:53.580721359 -0500
+@@ -352,6 +352,9 @@
+ # if defined(__tile__)
+ #   include "atomic_ops/sysdeps/gcc/tile.h"
+ # endif
++# if defined(__riscv)
++#   include "atomic_ops/sysdeps/gcc/riscv.h"
++# endif
+ #endif /* __GNUC__ && !AO_USE_PTHREAD_DEFS */
+ 
+ #if (defined(__IBMC__) || defined(__IBMCPP__)) && !defined(__GNUC__) \
+diff -Naur libatomic_ops-7.6.2-orig/src/Makefile.am libatomic_ops-7.6.2/src/Makefile.am
+--- libatomic_ops-7.6.2-orig/src/Makefile.am	2017-12-24 03:31:12.000000000 -0500
++++ libatomic_ops-7.6.2/src/Makefile.am	2018-02-18 00:48:53.579721342 -0500
+@@ -92,6 +92,7 @@
+           atomic_ops/sysdeps/gcc/mips.h \
+           atomic_ops/sysdeps/gcc/nios2.h \
+           atomic_ops/sysdeps/gcc/powerpc.h \
++          atomic_ops/sysdeps/gcc/riscv.h \
+           atomic_ops/sysdeps/gcc/s390.h \
+           atomic_ops/sysdeps/gcc/sh.h \
+           atomic_ops/sysdeps/gcc/sparc.h \
+diff -Naur libatomic_ops-7.6.2-orig/src/Makefile.in libatomic_ops-7.6.2/src/Makefile.in
+--- libatomic_ops-7.6.2-orig/src/Makefile.in	2017-12-24 03:32:23.000000000 -0500
++++ libatomic_ops-7.6.2/src/Makefile.in	2018-02-18 00:49:14.005062121 -0500
+@@ -446,6 +446,7 @@
+           atomic_ops/sysdeps/gcc/mips.h \
+           atomic_ops/sysdeps/gcc/nios2.h \
+           atomic_ops/sysdeps/gcc/powerpc.h \
++          atomic_ops/sysdeps/gcc/riscv.h \
+           atomic_ops/sysdeps/gcc/s390.h \
+           atomic_ops/sysdeps/gcc/sh.h \
+           atomic_ops/sysdeps/gcc/sparc.h \
diff --git a/pkgs/development/libraries/pcre/default.nix b/pkgs/development/libraries/pcre/default.nix
index b34c9ff31f2c..2ea5e923bad0 100644
--- a/pkgs/development/libraries/pcre/default.nix
+++ b/pkgs/development/libraries/pcre/default.nix
@@ -24,8 +24,7 @@ in stdenv.mkDerivation rec {
 
   outputs = [ "bin" "dev" "out" "doc" "man" ];
 
-  configureFlags = [
-    "--enable-jit"
+  configureFlags = optional (!hostPlatform.isRiscV) "--enable-jit" ++ [
     "--enable-unicode-properties"
     "--disable-cpp"
   ]
diff --git a/pkgs/development/tools/build-managers/gnumake/4.2/default.nix b/pkgs/development/tools/build-managers/gnumake/4.2/default.nix
index e175205143fc..1094cacb7af3 100644
--- a/pkgs/development/tools/build-managers/gnumake/4.2/default.nix
+++ b/pkgs/development/tools/build-managers/gnumake/4.2/default.nix
@@ -4,6 +4,8 @@ assert guileSupport -> ( pkgconfig != null && guile != null );
 
 let
   version = "4.2.1";
+
+  needGlibcPatch = (stdenv.cc.libc.version or "") == "2.27";
 in
 stdenv.mkDerivation {
   name = "gnumake-${version}";
@@ -20,7 +22,7 @@ stdenv.mkDerivation {
     # included Makefiles, don't look in /usr/include and friends.
     ./impure-dirs.patch
     ./pselect.patch
-  ];
+  ] ++ stdenv.lib.optional needGlibcPatch ./glibc-2.27.patch;
 
   nativeBuildInputs = stdenv.lib.optionals guileSupport [ pkgconfig ];
   buildInputs = stdenv.lib.optionals guileSupport [ guile ];
diff --git a/pkgs/development/tools/build-managers/gnumake/4.2/glibc-2.27.patch b/pkgs/development/tools/build-managers/gnumake/4.2/glibc-2.27.patch
new file mode 100644
index 000000000000..c2639c6cc927
--- /dev/null
+++ b/pkgs/development/tools/build-managers/gnumake/4.2/glibc-2.27.patch
@@ -0,0 +1,24 @@
+From 48c8a116a914a325a0497721f5d8b58d5bba34d4 Mon Sep 17 00:00:00 2001
+From: Paul Smith <psmith@gnu.org>
+Date: Sun, 19 Nov 2017 15:09:16 -0500
+Subject: * configure.ac: Support GLIBC glob interface version 2
+
+---
+ configure.ac | 3 +--
+ 1 file changed, 1 insertion(+), 2 deletions(-)
+
+diff -Naur a/configure b/configure
+--- configure	2016-06-10 19:03:21.000000000 -0400
++++ configure	2018-02-18 04:40:32.971371555 -0500
+@@ -11481,10 +11481,9 @@
+ #include <glob.h>
+ #include <fnmatch.h>
+ 
+-#define GLOB_INTERFACE_VERSION 1
+ #if !defined _LIBC && defined __GNU_LIBRARY__ && __GNU_LIBRARY__ > 1
+ # include <gnu-versions.h>
+-# if _GNU_GLOB_INTERFACE_VERSION == GLOB_INTERFACE_VERSION
++# if _GNU_GLOB_INTERFACE_VERSION == 1 || _GNU_GLOB_INTERFACE_VERSION == 2
+    gnu glob
+ # endif
+ #endif
diff --git a/pkgs/os-specific/linux/busybox/sandbox-shell.nix b/pkgs/os-specific/linux/busybox/sandbox-shell.nix
index 1755bd4f3f74..b94fae7f787b 100644
--- a/pkgs/os-specific/linux/busybox/sandbox-shell.nix
+++ b/pkgs/os-specific/linux/busybox/sandbox-shell.nix
@@ -1,8 +1,9 @@
-{ busybox }:
+{ busybox, hostPlatform }:
 
 # Minimal shell for use as basic /bin/sh in sandbox builds
 busybox.override {
-  useMusl = true;
+  # musl roadmap has RISC-V support projected for 1.1.20
+  useMusl = !hostPlatform.isRiscV;
   enableStatic = true;
   enableMinimal = true;
   extraConfig = ''
diff --git a/pkgs/stdenv/linux/make-bootstrap-tools-cross.nix b/pkgs/stdenv/linux/make-bootstrap-tools-cross.nix
index d08be79e6c55..6c217be4ea3c 100644
--- a/pkgs/stdenv/linux/make-bootstrap-tools-cross.nix
+++ b/pkgs/stdenv/linux/make-bootstrap-tools-cross.nix
@@ -17,4 +17,5 @@ in with (import ../../../lib).systems.examples; {
   i686-musl    = make musl32;
   armv6l-musl  = make muslpi;
   aarch64-musl = make aarch64-multiplatform-musl;
+  riscv64 = make riscv64;
 }
diff --git a/pkgs/stdenv/linux/make-bootstrap-tools.nix b/pkgs/stdenv/linux/make-bootstrap-tools.nix
index 86801e3f0447..71347ef83927 100644
--- a/pkgs/stdenv/linux/make-bootstrap-tools.nix
+++ b/pkgs/stdenv/linux/make-bootstrap-tools.nix
@@ -5,6 +5,7 @@
 let
   pkgs = import ../../.. { inherit localSystem crossSystem; };
   libc = pkgs.stdenv.cc.libc;
+  isl = with pkgs; if targetPlatform.isRiscV then isl_0_17 else isl_0_14;
 in with pkgs; rec {
 
 
@@ -19,7 +20,7 @@ in with pkgs; rec {
   tarMinimal = gnutar.override { acl = null; };
 
   busyboxMinimal = busybox.override {
-    useMusl = true;
+    useMusl = !targetPlatform.isRiscV;
     enableStatic = true;
     enableMinimal = true;
     extraConfig = ''
@@ -143,7 +144,7 @@ in with pkgs; rec {
         # These needed for cross but not native tools because the stdenv
         # GCC has certain things built in statically. See
         # pkgs/stdenv/linux/default.nix for the details.
-        cp -d ${isl_0_14.out}/lib/libisl*.so* $out/lib
+        cp -d ${isl.out}/lib/libisl*.so* $out/lib
 
       '' + ''
         cp -d ${bzip2.out}/lib/libbz2.so* $out/lib
diff --git a/pkgs/tools/package-management/nix/default.nix b/pkgs/tools/package-management/nix/default.nix
index 21b333f32316..f6e6988270ad 100644
--- a/pkgs/tools/package-management/nix/default.nix
+++ b/pkgs/tools/package-management/nix/default.nix
@@ -30,7 +30,7 @@ let
     buildInputs = [ curl openssl sqlite xz bzip2 ]
       ++ lib.optional (stdenv.isLinux || stdenv.isDarwin) libsodium
       ++ lib.optionals fromGit [ brotli ] # Since 1.12
-      ++ lib.optional stdenv.isLinux libseccomp
+      ++ lib.optional (stdenv.isLinux && !hostPlatform.isRiscV) libseccomp
       ++ lib.optional ((stdenv.isLinux || stdenv.isDarwin) && is20)
           (aws-sdk-cpp.override {
             apis = ["s3"];
@@ -55,7 +55,9 @@ let
       ]
       ++ lib.optional (
           hostPlatform != buildPlatform && hostPlatform ? nix && hostPlatform.nix ? system
-      ) ''--with-system=${hostPlatform.nix.system}'';
+      ) ''--with-system=${hostPlatform.nix.system}''
+         # RISC-V support in progress https://github.com/seccomp/libseccomp/pull/50
+      ++ lib.optional hostPlatform.isRiscV "--disable-seccomp-sandboxing";
 
     makeFlags = "profiledir=$(out)/etc/profile.d";
 
@@ -124,12 +126,12 @@ in rec {
 
   nixUnstable = (lib.lowPrio (common rec {
     name = "nix-2.0${suffix}";
-    suffix = "pre5950_3a5a241b";
+    suffix = "pre5951_690ac7c9";
     src = fetchFromGitHub {
       owner = "NixOS";
       repo = "nix";
-      rev = "3a5a241b3209f14f8801b902ba20b5cb0666c9df";
-      sha256 = "0cwjyhgyfzi2dz561nj897zhkbyx6lzi49avcyia2pr4498jcl6k";
+      rev = "690ac7c90b5bf3c599e210c53365c7d229c8b0ff";
+      sha256 = "1yn2p38kp1i67makbawr1rhdiwihgnvk2zwrz0gvf6q65mj2k89c";
     };
     fromGit = true;
   })) // { perl-bindings = perl-bindings { nix = nixUnstable; }; };
diff --git a/pkgs/top-level/all-packages.nix b/pkgs/top-level/all-packages.nix
index 925cd63a714a..e1fa50cffa94 100644
--- a/pkgs/top-level/all-packages.nix
+++ b/pkgs/top-level/all-packages.nix
@@ -5790,8 +5790,12 @@ with pkgs;
   gambit = callPackage ../development/compilers/gambit { };
   gerbil = callPackage ../development/compilers/gerbil { };
 
-  gccFun = callPackage ../development/compilers/gcc/6;
-  gcc = gcc6;
+  # !!! When updating to gcc7 everywhere we can get rid of the
+  # isRiscV overrides here and in gccCrossStageStatic
+  gccFun6 = callPackage ../development/compilers/gcc/6;
+  gccFun7 = callPackage ../development/compilers/gcc/7;
+  gccFun = if targetPlatform.isRiscV then gccFun7 else gccFun6;
+  gcc = if targetPlatform.isRiscV then gcc7 else gcc6;
   gcc-unwrapped = gcc.cc;
 
   gccStdenv = if stdenv.cc.isGNU then stdenv else stdenv.override {
@@ -5871,6 +5875,7 @@ with pkgs;
       bintools = binutils-unwrapped;
       libc = libcCross1;
     };
+    isl = if targetPlatform.isRiscV then isl_0_17 else isl_0_14;
     in wrapCCWith {
       name = "gcc-cross-wrapper";
       cc = gccFun {
@@ -5878,7 +5883,7 @@ with pkgs;
         inherit noSysDirs;
         # PGO seems to speed up compilation by gcc by ~10%, see #445 discussion
         profiledCompiler = with stdenv; (!isDarwin && (isi686 || isx86_64));
-        isl = if !stdenv.isDarwin then isl_0_14 else null;
+        isl = if !stdenv.isDarwin then isl else null;
 
         # just for stage static
         crossStageStatic = true;
@@ -8764,7 +8769,11 @@ with pkgs;
   };
 
   # Being redundant to avoid cycles on boot. TODO: find a better way
-  glibcCross = callPackage ../development/libraries/glibc {
+  glibcCross = let
+    expr = if hostPlatform.isRiscV
+             then ../development/libraries/glibc/2.27.nix
+           else ../development/libraries/glibc;
+  in callPackage expr {
     installLocales = config.glibc.locales or false;
     stdenv = crossLibcStdenv;
   };
@@ -12943,7 +12952,7 @@ with pkgs;
 
   inherit (callPackages ../os-specific/linux/kernel-headers { })
     linuxHeaders_4_4 linuxHeaders_4_15;
-  linuxHeaders = if hostPlatform.isMusl then linuxHeaders_4_15 else linuxHeaders_4_4;
+  linuxHeaders = if hostPlatform.isMusl || hostPlatform.isRiscV then linuxHeaders_4_15 else linuxHeaders_4_4;
 
   kernelPatches = callPackage ../os-specific/linux/kernel/patches.nix { };