--- a/b2g/config/mozconfigs/common
+++ b/b2g/config/mozconfigs/common
@@ -7,17 +7,17 @@
 . "$topsrcdir/build/mozconfig.common"
 
 # Normally, we'd set this unconditionally, but this file is also used
 # for local builds and there is no other mozconfig in this tree that
 # is included on device builds.
 if test -d $topsrcdir/gcc/bin; then
     HOST_CC="$topsrcdir/gcc/bin/gcc"
     HOST_CXX="$topsrcdir/gcc/bin/g++"
-    ac_add_options --enable-stdcxx-compat
+    . "$topsrcdir/build/unix/mozconfig.stdcxx"
 fi
 
 # Allow overriding this from the environment, and don't
 # try to set it if it doesn't exist. As per above, this file is also
 # used for local builds, and we may need to override this for builds in
 # other environments.
 if test -z "$SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE" -a -f /builds/crash-stats-api.token; then
   export SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE=/builds/crash-stats-api.token

--- a/b2g/graphene/config/horizon-mozconfigs/common
+++ b/b2g/graphene/config/horizon-mozconfigs/common
@@ -11,14 +11,14 @@ MOZ_AUTOMATION_SDK=0
 . "$topsrcdir/build/mozconfig.common"
 
 # Normally, we'd set this unconditionally, but this file is also used
 # for local builds and there is no other mozconfig in this tree that
 # is included on device builds.
 if test -d $topsrcdir/../gcc/bin; then
     HOST_CC="$topsrcdir/../gcc/bin/gcc"
     HOST_CXX="$topsrcdir/../gcc/bin/g++"
-    ac_add_options --enable-stdcxx-compat
+    . "$topsrcdir/build/unix/mozconfig.stdcxx"
 fi
 
 MOZ_HORIZON=1
 ac_add_options --with-branding=b2g/branding/horizon
 ac_add_options --enable-application=b2g/graphene

--- a/b2g/graphene/config/mozconfigs/common
+++ b/b2g/graphene/config/mozconfigs/common
@@ -11,14 +11,14 @@ MOZ_AUTOMATION_SDK=0
 . "$topsrcdir/build/mozconfig.common"
 
 # Normally, we'd set this unconditionally, but this file is also used
 # for local builds and there is no other mozconfig in this tree that
 # is included on device builds.
 if test -d $topsrcdir/../gcc/bin; then
     HOST_CC="$topsrcdir/../gcc/bin/gcc"
     HOST_CXX="$topsrcdir/../gcc/bin/g++"
-    ac_add_options --enable-stdcxx-compat
+    . "$topsrcdir/build/unix/mozconfig.stdcxx"
 fi
 
 ac_add_options --with-branding=b2g/branding/browserhtml
 ac_add_options --enable-application=b2g/graphene
 

--- a/browser/config/mozconfigs/linux64/debug-static-analysis-clang
+++ b/browser/config/mozconfigs/linux64/debug-static-analysis-clang
@@ -12,16 +12,15 @@ export CC="$topsrcdir/clang/bin/clang"
 export CXX="$topsrcdir/clang/bin/clang++"
 
 # Add the static checker
 ac_add_options --enable-clang-plugin
 
 # Treat warnings as errors (modulo ALLOW_COMPILER_WARNINGS).
 ac_add_options --enable-warnings-as-errors
 
-# Avoid dependency on libstdc++ 4.7
-ac_add_options --enable-stdcxx-compat
+. "$topsrcdir/build/unix/mozconfig.stdcxx"
 
 export PKG_CONFIG_LIBDIR=/usr/lib64/pkgconfig:/usr/share/pkgconfig
 . $topsrcdir/build/unix/mozconfig.gtk
 
 . "$topsrcdir/build/mozconfig.common.override"
 . "$topsrcdir/build/mozconfig.cache"

--- a/browser/config/mozconfigs/linux64/hazards
+++ b/browser/config/mozconfigs/linux64/hazards
@@ -4,17 +4,18 @@
 
 # Do NOT include build/unix/mozconfig.linux because it points directly at the
 # tooltool-installed gcc, and the analysis works by wrapping the gcc invocation
 # with a script that invokes the real gcc with -fplugin and its configuration
 # directives. Instead, duplicate the contents of that mozconfig here:
 
 . "$topsrcdir/build/mozconfig.common"
 ac_add_options --enable-elf-hack
-ac_add_options --enable-stdcxx-compat
+
+. "$topsrcdir/build/unix/mozconfig.stdcxx"
 
 # The objdir must be at a known location so its path can be stripped from the
 # filenames stored by the analysis
 mk_add_options MOZ_OBJDIR=obj-analyzed
 
 # The configuration options are chosen to compile the most code
 # (--enable-debug, --enable-tests) in the trickiest way possible
 # (--enable-optimize) to maximize the chance of seeing tricky static orderings.

--- a/browser/config/mozconfigs/linux64/opt-static-analysis-clang
+++ b/browser/config/mozconfigs/linux64/opt-static-analysis-clang
@@ -11,16 +11,15 @@ CC="$topsrcdir/clang/bin/clang"
 CXX="$topsrcdir/clang/bin/clang++"
 
 # Add the static checker
 ac_add_options --enable-clang-plugin
 
 # Treat warnings as errors (modulo ALLOW_COMPILER_WARNINGS).
 ac_add_options --enable-warnings-as-errors
 
-# Avoid dependency on libstdc++ 4.7
-ac_add_options --enable-stdcxx-compat
+. "$topsrcdir/build/unix/mozconfig.stdcxx"
 
 export PKG_CONFIG_LIBDIR=/usr/lib64/pkgconfig:/usr/share/pkgconfig
 . $topsrcdir/build/unix/mozconfig.gtk
 
 . "$topsrcdir/build/mozconfig.common.override"
 . "$topsrcdir/build/mozconfig.cache"

--- a/browser/config/tooltool-manifests/linux64/asan.manifest
+++ b/browser/config/tooltool-manifests/linux64/asan.manifest
@@ -1,10 +1,18 @@
 [
 {
+"version": "gcc 4.8.5 + PR64905",
+"size": 80160264,
+"digest": "c1a9dc9da289b8528874d16300b9d13a997cec99195bb0bc46ff665216d8535d6d6cb5af6b4b1f2749af6815dab12e703fdb3849014e5c23a70eff351a0baf4e",
+"algorithm": "sha512",
+"filename": "gcc.tar.xz",
+"unpack": true
+},
+{
 "version": "clang 3.5/r200213",
 "size": 71282740, 
 "digest": "ee9edb1ef3afd9ab29e39565145545ad57e8d8d2538be4d822d7dbd64038f4529b0b287cecf48bf83def52a26ac2c6faa331686c3ad5e8b4ba4c22686ee0808f", 
 "algorithm": "sha512", 
 "filename": "clang.tar.bz2",
 "unpack": true
 },
 {

--- a/build/unix/mozconfig.asan
+++ b/build/unix/mozconfig.asan
@@ -19,10 +19,9 @@ ac_add_options --enable-address-sanitize
 # Mandatory options required for ASan builds (both on Linux and Mac)
 export MOZ_DEBUG_SYMBOLS=1
 ac_add_options --enable-debug-symbols
 ac_add_options --disable-install-strip
 ac_add_options --disable-jemalloc
 ac_add_options --disable-crashreporter
 ac_add_options --disable-elf-hack
 
-# Avoid dependency on libstdc++ 4.7
-ac_add_options --enable-stdcxx-compat
+. "$topsrcdir/build/unix/mozconfig.stdcxx"

--- a/build/unix/mozconfig.gtk
+++ b/build/unix/mozconfig.gtk
@@ -18,9 +18,11 @@ LDFLAGS="-L$TOOLTOOL_DIR/gtk3/usr/local/
 ac_add_options --enable-default-toolkit=cairo-gtk3
 
 # Set things up to use Gtk+3 from the tooltool package
 mk_add_options "export FONTCONFIG_PATH=$TOOLTOOL_DIR/gtk3/usr/local/etc/fonts"
 mk_add_options "export PANGO_SYSCONFDIR=$TOOLTOOL_DIR/gtk3/usr/local/etc"
 mk_add_options "export PANGO_LIBDIR=$TOOLTOOL_DIR/gtk3/usr/local/lib"
 mk_add_options "export GDK_PIXBUF_MODULE_FILE=$TOOLTOOL_DIR/gtk3/usr/local/lib/gdk-pixbuf-2.0/2.10.0/loaders.cache"
 mk_add_options "export GDK_PIXBUF_MODULEDIR=$TOOLTOOL_DIR/gtk3/usr/local/lib/gdk-pixbuf-2.0/2.10.0/loaders"
-mk_add_options "export LD_LIBRARY_PATH=$TOOLTOOL_DIR/gtk3/usr/local/lib"
+
+LD_LIBRARY_PATH=${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}$TOOLTOOL_DIR/gtk3/usr/local/lib
+mk_add_options "export LD_LIBRARY_PATH=$LD_LIBRARY_PATH"

--- a/build/unix/mozconfig.linux
+++ b/build/unix/mozconfig.linux
@@ -23,17 +23,16 @@ then
   mk_add_options PATH="$TOOLTOOL_DIR/gcc/bin:$PATH"
 else
   CC="/tools/gcc-4.7.3-0moz1/bin/gcc"
   CXX="/tools/gcc-4.7.3-0moz1/bin/g++"
 fi
 
 ac_add_options --enable-elf-hack
 
-# Avoid dependency on libstdc++ 4.7
-ac_add_options --enable-stdcxx-compat
+. "$topsrcdir/build/unix/mozconfig.stdcxx"
 
 # PKG_CONFIG_LIBDIR is appropriately overridden in mozconfig.linux32
 export PKG_CONFIG_LIBDIR=/usr/lib64/pkgconfig:/usr/share/pkgconfig
 
 export SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE=/builds/crash-stats-api.token
 
 . "$topsrcdir/build/unix/mozconfig.gtk"

new file mode 100644
--- /dev/null
+++ b/build/unix/mozconfig.stdcxx
@@ -0,0 +1,15 @@
+# Avoid dependency on libstdc++ 4.7
+ac_add_options --enable-stdcxx-compat
+
+TOOLTOOL_DIR=${TOOLTOOL_DIR:-$topsrcdir}
+
+if [ -f "$TOOLTOOL_DIR/clang/lib/libstdc++.so" ]; then
+  LD_LIBRARY_PATH=${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}$TOOLTOOL_DIR/clang/lib
+elif [ -f "$TOOLTOOL_DIR/gcc/lib/libstdc++.so" ]; then
+  # We put both 32-bits and 64-bits library path in LD_LIBRARY_PATH: ld.so
+  # will prefer the files in the 32-bits path when loading 32-bits executables,
+  # and the files in the 64-bits path when loading 64-bits executables.
+  LD_LIBRARY_PATH=${LD_LIBRARY_PATH:+$LD_LIBRARY_PATH:}$TOOLTOOL_DIR/gcc/lib64:$TOOLTOOL_DIR/gcc/lib
+fi
+
+mk_add_options "export LD_LIBRARY_PATH=$LD_LIBRARY_PATH"

--- a/build/unix/mozconfig.tsan
+++ b/build/unix/mozconfig.tsan
@@ -25,10 +25,9 @@ ac_add_options --disable-crashreporter
 ac_add_options --disable-elf-hack
 ac_add_options --enable-pie
 
 # Keep symbols to symbolize TSan traces
 ac_add_options --disable-install-strip
 # -gline-tables-only results in significantly smaller binaries.
 ac_add_options --enable-debug-symbols="-gline-tables-only"
 
-# Avoid dependency on libstdc++ 4.7
-ac_add_options --enable-stdcxx-compat
+. "$topsrcdir/build/unix/mozconfig.stdcxx"

--- a/mobile/android/config/mozconfigs/common
+++ b/mobile/android/config/mozconfigs/common
@@ -72,15 +72,14 @@ export SOCORRO_SYMBOL_UPLOAD_TOKEN_FILE=
 export MOZ_PACKAGE_JSSHELL=1
 
 # Use ccache
 . "$topsrcdir/build/mozconfig.cache"
 
 HOST_CC="$topsrcdir/gcc/bin/gcc"
 HOST_CXX="$topsrcdir/gcc/bin/g++"
 
-# Avoid dependency on libstdc++ 4.7
-ac_add_options --enable-stdcxx-compat
+. "$topsrcdir/build/unix/mozconfig.stdcxx"
 
 # Use libc++ as our C++ standard library
 ac_add_options --with-android-cxx-stl=libc++
 
 JS_BINARY="$topsrcdir/mobile/android/config/js_wrapper.sh"