diff --git a/pkgs/development/compilers/llvm/3.5/libc++/default.nix b/pkgs/development/compilers/llvm/3.5/libc++/default.nix
index abc198b0686..1f1129f578f 100644
--- a/pkgs/development/compilers/llvm/3.5/libc++/default.nix
+++ b/pkgs/development/compilers/llvm/3.5/libc++/default.nix
@@ -20,7 +20,11 @@ stdenv.mkDerivation rec {
                 '"${libcxxabi}/lib/libc++abi.dylib"'
   '';
 
-  patches = [ ./darwin.patch ];
+  patches = [
+    ./darwin.patch
+    # glibc 2.26 fix
+    ./xlocale-glibc-2.26.patch
+  ];
 
   buildInputs = [ cmake libcxxabi ] ++ lib.optional stdenv.isDarwin fixDarwinDylibNames;
 
diff --git a/pkgs/development/compilers/llvm/3.5/libc++/xlocale-glibc-2.26.patch b/pkgs/development/compilers/llvm/3.5/libc++/xlocale-glibc-2.26.patch
new file mode 100644
index 00000000000..250bb49fc23
--- /dev/null
+++ b/pkgs/development/compilers/llvm/3.5/libc++/xlocale-glibc-2.26.patch
@@ -0,0 +1,17 @@
+diff --git a/include/__locale b/include/__locale
+index 3daa1f1..cb8e151 100644
+--- a/include/__locale
++++ b/include/__locale
+@@ -29,10 +29,10 @@
+ # if __ANDROID_API__ <= 20
+ #  include <support/android/locale_bionic.h>
+ # endif
+-#elif (defined(__GLIBC__) || defined(__APPLE__)      || defined(__FreeBSD__) \
++#elif (defined(__APPLE__)      || defined(__FreeBSD__) \
+     || defined(__sun__)   || defined(__EMSCRIPTEN__) || defined(__IBMCPP__))
+ # include <xlocale.h>
+-#endif // __GLIBC__ || __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
++#endif // __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
+ 
+ #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+ #pragma GCC system_header
diff --git a/pkgs/development/compilers/llvm/3.7/libc++/default.nix b/pkgs/development/compilers/llvm/3.7/libc++/default.nix
index 69ce87bcbf3..4296c0fd192 100644
--- a/pkgs/development/compilers/llvm/3.7/libc++/default.nix
+++ b/pkgs/development/compilers/llvm/3.7/libc++/default.nix
@@ -17,6 +17,8 @@ stdenv.mkDerivation rec {
   patches = [
     ./darwin.patch
     ./r242056.patch
+    # glibc 2.26 fix
+    ./xlocale-glibc-2.26.patch
   ];
 
   buildInputs = [ cmake libcxxabi ] ++ lib.optional stdenv.isDarwin fixDarwinDylibNames;
diff --git a/pkgs/development/compilers/llvm/3.7/libc++/xlocale-glibc-2.26.patch b/pkgs/development/compilers/llvm/3.7/libc++/xlocale-glibc-2.26.patch
new file mode 100644
index 00000000000..5ee8f6b8230
--- /dev/null
+++ b/pkgs/development/compilers/llvm/3.7/libc++/xlocale-glibc-2.26.patch
@@ -0,0 +1,17 @@
+diff --git a/include/__locale b/include/__locale
+index 1989558..1e42905 100644
+--- a/include/__locale
++++ b/include/__locale
+@@ -34,10 +34,10 @@
+ # include <support/solaris/xlocale.h>
+ #elif defined(_NEWLIB_VERSION)
+ # include <support/newlib/xlocale.h>
+-#elif (defined(__GLIBC__) || defined(__APPLE__)      || defined(__FreeBSD__) \
++#elif (defined(__APPLE__)      || defined(__FreeBSD__) \
+     || defined(__EMSCRIPTEN__) || defined(__IBMCPP__))
+ # include <xlocale.h>
+-#endif // __GLIBC__ || __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
++#endif // __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
+ 
+ #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+ #pragma GCC system_header
diff --git a/pkgs/development/compilers/llvm/3.8/libc++/default.nix b/pkgs/development/compilers/llvm/3.8/libc++/default.nix
index e4198599904..ea468b3772e 100644
--- a/pkgs/development/compilers/llvm/3.8/libc++/default.nix
+++ b/pkgs/development/compilers/llvm/3.8/libc++/default.nix
@@ -14,7 +14,10 @@ stdenv.mkDerivation rec {
     cmakeFlagsArray=($cmakeFlagsArray -DLIBCXX_CXX_ABI_INCLUDE_PATHS="$NIX_BUILD_TOP/libcxxabi-${version}.src/include")
   '';
 
-  patches = lib.optional stdenv.isDarwin ./darwin.patch;
+  patches = [
+    # glibc 2.26 fix
+    ../../3.9/libc++/xlocale-glibc-2.26.patch
+  ] ++ lib.optional stdenv.isDarwin ./darwin.patch;
 
   buildInputs = [ cmake libcxxabi ] ++ lib.optional stdenv.isDarwin fixDarwinDylibNames;
 
diff --git a/pkgs/development/compilers/llvm/3.9/libc++/default.nix b/pkgs/development/compilers/llvm/3.9/libc++/default.nix
index f656f553f16..ad514b0daa5 100644
--- a/pkgs/development/compilers/llvm/3.9/libc++/default.nix
+++ b/pkgs/development/compilers/llvm/3.9/libc++/default.nix
@@ -14,7 +14,10 @@ stdenv.mkDerivation rec {
     cmakeFlagsArray=($cmakeFlagsArray -DLIBCXX_CXX_ABI_INCLUDE_PATHS="$NIX_BUILD_TOP/libcxxabi-${version}.src/include")
   '';
 
-  patches = lib.optional stdenv.isDarwin ./darwin.patch;
+  patches = [
+    # glibc 2.26 fix
+    ./xlocale-glibc-2.26.patch
+  ] ++ lib.optional stdenv.isDarwin ./darwin.patch;
 
   buildInputs = [ cmake libcxxabi ] ++ lib.optional stdenv.isDarwin fixDarwinDylibNames;
 
diff --git a/pkgs/development/compilers/llvm/3.9/libc++/xlocale-glibc-2.26.patch b/pkgs/development/compilers/llvm/3.9/libc++/xlocale-glibc-2.26.patch
new file mode 100644
index 00000000000..4cc042554c8
--- /dev/null
+++ b/pkgs/development/compilers/llvm/3.9/libc++/xlocale-glibc-2.26.patch
@@ -0,0 +1,19 @@
+diff --git a/include/__locale b/include/__locale
+index 7bc701d..ea75c86 100644
+--- a/include/__locale
++++ b/include/__locale
+@@ -34,12 +34,12 @@
+ # include <support/solaris/xlocale.h>
+ #elif defined(_NEWLIB_VERSION)
+ # include <support/newlib/xlocale.h>
+-#elif (defined(__GLIBC__) || defined(__APPLE__)      || defined(__FreeBSD__) \
++#elif (defined(__APPLE__)      || defined(__FreeBSD__) \
+     || defined(__EMSCRIPTEN__) || defined(__IBMCPP__))
+ # include <xlocale.h>
+ #elif defined(_LIBCPP_HAS_MUSL_LIBC)
+ # include <support/musl/xlocale.h>
+-#endif // __GLIBC__ || __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
++#endif // __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
+ 
+ #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+ #pragma GCC system_header
diff --git a/pkgs/development/compilers/llvm/4/libc++/default.nix b/pkgs/development/compilers/llvm/4/libc++/default.nix
index b74d2fb89dc..db751bcffd4 100644
--- a/pkgs/development/compilers/llvm/4/libc++/default.nix
+++ b/pkgs/development/compilers/llvm/4/libc++/default.nix
@@ -10,8 +10,12 @@ stdenv.mkDerivation rec {
     export LIBCXXABI_INCLUDE_DIR="$PWD/$(ls -d libcxxabi-${version}*)/include"
   '';
 
-  # https://github.com/llvm-mirror/libcxx/commit/bcc92d75df0274b9593ebd097fcae60494e3bffc
-  patches = [ ./pthread_mach_thread_np.patch ];
+  patches = [
+    # https://github.com/llvm-mirror/libcxx/commit/bcc92d75df0274b9593ebd097fcae60494e3bffc
+    ./pthread_mach_thread_np.patch
+    # glibc 2.26 fix
+    ./xlocale-glibc-2.26.patch
+  ];
 
   prePatch = ''
     substituteInPlace lib/CMakeLists.txt --replace "/usr/lib/libc++" "\''${LIBCXX_LIBCXXABI_LIB_PATH}/libc++"
diff --git a/pkgs/development/compilers/llvm/4/libc++/xlocale-glibc-2.26.patch b/pkgs/development/compilers/llvm/4/libc++/xlocale-glibc-2.26.patch
new file mode 100644
index 00000000000..e411d85066b
--- /dev/null
+++ b/pkgs/development/compilers/llvm/4/libc++/xlocale-glibc-2.26.patch
@@ -0,0 +1,19 @@
+diff --git a/include/__locale b/include/__locale
+index f4882de..29443b4 100644
+--- a/include/__locale
++++ b/include/__locale
+@@ -34,12 +34,12 @@
+ # include <support/solaris/xlocale.h>
+ #elif defined(_NEWLIB_VERSION)
+ # include <support/newlib/xlocale.h>
+-#elif (defined(__GLIBC__) || defined(__APPLE__)      || defined(__FreeBSD__) \
++#elif (defined(__APPLE__)      || defined(__FreeBSD__) \
+     || defined(__EMSCRIPTEN__) || defined(__IBMCPP__))
+ # include <xlocale.h>
+ #elif defined(_LIBCPP_HAS_MUSL_LIBC)
+ # include <support/musl/xlocale.h>
+-#endif // __GLIBC__ || __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
++#endif // __APPLE__ || __FreeBSD__ || __sun__ || __EMSCRIPTEN__ || __IBMCPP__
+ 
+ #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
+ #pragma GCC system_header