diff --git a/Makefile b/Makefile
index 016768e72e43..cc47f0d9cf90 100644
--- a/Makefile
+++ b/Makefile
@@ -131,6 +131,7 @@ cross-compile-build-tools:
 	  ENABLE_COVERAGE=$(ENABLE_COVERAGE) \
 	  DISABLE_ASSERTIONS=$(DISABLE_ASSERTIONS) \
 	  ENABLE_EXPENSIVE_CHECKS=$(ENABLE_EXPENSIVE_CHECKS) \
+	  ENABLE_LIBCPP=$(ENABLE_LIBCPP) \
 	  CFLAGS= \
 	  CXXFLAGS= \
 	) || exit 1;
diff --git a/Makefile.config.in b/Makefile.config.in
index 3961cc96c795..47044a3a8d3d 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -208,6 +208,10 @@ RDYNAMIC := @RDYNAMIC@
 # These are options that can either be enabled here, or can be enabled on the
 # make command line (ie, make ENABLE_PROFILING=1):
 
+# When ENABLE_LIBCPP is enabled, LLVM uses libc++ by default to build.
+#ENABLE_LIBCPP = 0
+ENABLE_LIBCPP = @ENABLE_LIBCPP@
+
 # When ENABLE_OPTIMIZED is enabled, LLVM code is optimized and output is put
 # into the "Release" directories. Otherwise, LLVM code is not optimized and
 # output is put in the "Debug" directories.
diff --git a/Makefile.rules b/Makefile.rules
index 6b68cf2c6b86..49f5edd9d845 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -301,8 +301,10 @@ else
   endif
 endif
 
-#CXX.Flags +=  -stdlib=libc++
-#LD.Flags +=  -stdlib=libc++
+ifeq ($(ENABLE_LIBCPP),1)
+  CXX.Flags +=  -stdlib=libc++
+  LD.Flags +=  -stdlib=libc++
+endif
 
 ifeq ($(ENABLE_PROFILING),1)
   BuildMode := $(BuildMode)+Profile
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 6e9d8485866c..090f5dc12d65 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -415,6 +415,18 @@ dnl=== SECTION 3: Command line arguments for the configure script.
 dnl===
 dnl===-----------------------------------------------------------------------===
 
+dnl --enable-libcpp : check whether or not to use libc++ on the command line
+AC_ARG_ENABLE(libcpp,
+              AS_HELP_STRING([--enable-libcpp],
+                             [Use libc++ if available (default is NO)]),,
+                             enableval=default)
+case "$enableval" in
+  yes) AC_SUBST(ENABLE_LIBCPP,[1]) ;;
+  no)  AC_SUBST(ENABLE_LIBCPP,[0]) ;;
+  default) AC_SUBST(ENABLE_LIBCPP,[0]);;
+  *) AC_MSG_ERROR([Invalid setting for --enable-libcpp. Use "yes" or "no"]) ;;
+esac
+
 dnl --enable-optimized : check whether they want to do an optimized build:
 AC_ARG_ENABLE(optimized, AS_HELP_STRING(
  --enable-optimized,[Compile with optimizations enabled (default is NO)]),,enableval=$optimize)
diff --git a/configure b/configure
index ae6be9d535ef..09173d257f30 100755
--- a/configure
+++ b/configure
@@ -682,6 +682,7 @@ BUILD_CC
 BUILD_EXEEXT
 BUILD_CXX
 CVSBUILD
+ENABLE_LIBCPP
 ENABLE_OPTIMIZED
 ENABLE_PROFILING
 DISABLE_ASSERTIONS
@@ -1389,6 +1390,7 @@ Optional Features:
   --disable-FEATURE       do not include FEATURE (same as --enable-FEATURE=no)
   --enable-FEATURE[=ARG]  include FEATURE [ARG=yes]
   --enable-polly          Use polly if available (default is YES)
+  --enable-libcpp         Use libc++ if available (default is NO)
   --enable-optimized      Compile with optimizations enabled (default is NO)
   --enable-profiling      Compile with profiling enabled (default is NO)
   --enable-assertions     Compile with assertion checks enabled (default is
@@ -1415,8 +1417,8 @@ Optional Features:
                           (default is YES)
   --enable-targets        Build specific host targets: all or
                           target1,target2,... Valid targets are: host, x86,
-                          x86_64, sparc, powerpc, arm, mips, spu,
-                          xcore, msp430, ptx, cbe, and cpp (default=all)
+                          x86_64, sparc, powerpc, arm, mips, spu, xcore,
+                          msp430, ptx, cbe, and cpp (default=all)
   --enable-cbe-printf-a   Enable C Backend output with hex floating point via
                           %a (default is YES)
   --enable-bindings       Build specific language bindings:
@@ -4956,6 +4958,25 @@ else
 fi
 
 
+# Check whether --enable-libcpp was given.
+if test "${enable_libcpp+set}" = set; then
+  enableval=$enable_libcpp;
+else
+  enableval=default
+fi
+
+case "$enableval" in
+  yes) ENABLE_LIBCPP=1
+ ;;
+  no)  ENABLE_LIBCPP=0
+ ;;
+  default) ENABLE_LIBCPP=0
+;;
+  *) { { echo "$as_me:$LINENO: error: Invalid setting for --enable-libcpp. Use \"yes\" or \"no\"" >&5
+echo "$as_me: error: Invalid setting for --enable-libcpp. Use \"yes\" or \"no\"" >&2;}
+   { (exit 1); exit 1; }; } ;;
+esac
+
 # Check whether --enable-optimized was given.
 if test "${enable_optimized+set}" = set; then
   enableval=$enable_optimized;
@@ -10455,7 +10476,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10463 "configure"
+#line 10479 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -21845,6 +21866,7 @@ BUILD_CC!$BUILD_CC$ac_delim
 BUILD_EXEEXT!$BUILD_EXEEXT$ac_delim
 BUILD_CXX!$BUILD_CXX$ac_delim
 CVSBUILD!$CVSBUILD$ac_delim
+ENABLE_LIBCPP!$ENABLE_LIBCPP$ac_delim
 ENABLE_OPTIMIZED!$ENABLE_OPTIMIZED$ac_delim
 ENABLE_PROFILING!$ENABLE_PROFILING$ac_delim
 DISABLE_ASSERTIONS!$DISABLE_ASSERTIONS$ac_delim
@@ -21861,7 +21883,6 @@ ENABLE_PTHREADS!$ENABLE_PTHREADS$ac_delim
 ENABLE_PIC!$ENABLE_PIC$ac_delim
 ENABLE_SHARED!$ENABLE_SHARED$ac_delim
 ENABLE_EMBED_STDCXX!$ENABLE_EMBED_STDCXX$ac_delim
-ENABLE_TIMESTAMPS!$ENABLE_TIMESTAMPS$ac_delim
 _ACEOF
 
   if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 97; then
@@ -21903,6 +21924,7 @@ _ACEOF
 ac_delim='%!_!# '
 for ac_last_try in false false false false false :; do
   cat >conf$$subs.sed <<_ACEOF
+ENABLE_TIMESTAMPS!$ENABLE_TIMESTAMPS$ac_delim
 TARGETS_TO_BUILD!$TARGETS_TO_BUILD$ac_delim
 LLVM_ENUM_TARGETS!$LLVM_ENUM_TARGETS$ac_delim
 LLVM_ENUM_ASM_PRINTERS!$LLVM_ENUM_ASM_PRINTERS$ac_delim
@@ -21994,7 +22016,7 @@ LIBOBJS!$LIBOBJS$ac_delim
 LTLIBOBJS!$LTLIBOBJS$ac_delim
 _ACEOF
 
-  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 89; then
+  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 90; then
     break
   elif $ac_last_try; then
     { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5