diff --git a/Makefile.config.in b/Makefile.config.in
index e644c03a782..6d06f16b357 100644
--- a/Makefile.config.in
+++ b/Makefile.config.in
@@ -221,6 +221,9 @@ ENABLE_LIBCPP = @ENABLE_LIBCPP@
 # When ENABLE_CXX11 is enabled, LLVM uses c++11 mode by default to build.
 ENABLE_CXX11 = @ENABLE_CXX11@
 
+# When ENABLE_WERROR is enabled, we'll pass -Werror on the command line
+ENABLE_WERROR = @ENABLE_WERROR@
+
 # 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 ebbaba8facf..289adc2be42 100644
--- a/Makefile.rules
+++ b/Makefile.rules
@@ -321,6 +321,11 @@ ifeq ($(ENABLE_CXX11),1)
   CXX.Flags += -std=c++11
 endif
 
+ifeq ($(ENABLE_WERROR),1)
+  CXX.Flags += -Werror
+  C.Flags += -Werror
+endif
+
 ifeq ($(ENABLE_PROFILING),1)
   BuildMode := $(BuildMode)+Profile
   CXX.Flags := $(filter-out -fomit-frame-pointer,$(CXX.Flags)) -pg -g
diff --git a/autoconf/configure.ac b/autoconf/configure.ac
index 413a1eefe64..4d3a14efd4e 100644
--- a/autoconf/configure.ac
+++ b/autoconf/configure.ac
@@ -502,6 +502,16 @@ else
   AC_SUBST(DISABLE_ASSERTIONS,[[DISABLE_ASSERTIONS=1]])
 fi
 
+dnl --enable-werror : check whether we want Werror on by default
+AC_ARG_ENABLE(werror,AS_HELP_STRING(
+  --enable-werror,[Compile with -Werror enabled (default is NO)]),, enableval="no")
+case "$enableval" in
+  yes) AC_SUBST(ENABLE_WERROR,[1]) ;;
+  no)  AC_SUBST(ENABLE_WERROR,[0]) ;;
+  default) AC_SUBST(ENABLE_WERROR,[0]);;
+  *) AC_MSG_ERROR([Invalid setting for --enable-werror. Use "yes" or "no"]) ;;
+esac
+
 dnl --enable-expensive-checks : check whether they want to turn on expensive debug checks:
 AC_ARG_ENABLE(expensive-checks,AS_HELP_STRING(
   --enable-expensive-checks,[Compile with expensive debug checks enabled (default is NO)]),, enableval="no")
diff --git a/configure b/configure
index 01357a928d0..9c89a334aba 100755
--- a/configure
+++ b/configure
@@ -688,6 +688,7 @@ ENABLE_CXX11
 ENABLE_OPTIMIZED
 ENABLE_PROFILING
 DISABLE_ASSERTIONS
+ENABLE_WERROR
 ENABLE_EXPENSIVE_CHECKS
 EXPENSIVE_CHECKS
 DEBUG_RUNTIME
@@ -1399,6 +1400,7 @@ Optional Features:
   --enable-profiling      Compile with profiling enabled (default is NO)
   --enable-assertions     Compile with assertion checks enabled (default is
                           YES)
+  --enable-werror         Compile with -Werror enabled (default is NO)
   --enable-expensive-checks
                           Compile with expensive debug checks enabled (default
                           is NO)
@@ -5085,6 +5087,25 @@ else
 
 fi
 
+# Check whether --enable-werror was given.
+if test "${enable_werror+set}" = set; then
+  enableval=$enable_werror;
+else
+  enableval="no"
+fi
+
+case "$enableval" in
+  yes) ENABLE_WERROR=1
+ ;;
+  no)  ENABLE_WERROR=0
+ ;;
+  default) ENABLE_WERROR=0
+;;
+  *) { { echo "$as_me:$LINENO: error: Invalid setting for --enable-werror. Use \"yes\" or \"no\"" >&5
+echo "$as_me: error: Invalid setting for --enable-werror. Use \"yes\" or \"no\"" >&2;}
+   { (exit 1); exit 1; }; } ;;
+esac
+
 # Check whether --enable-expensive-checks was given.
 if test "${enable_expensive_checks+set}" = set; then
   enableval=$enable_expensive_checks;
@@ -10234,7 +10255,7 @@ else
   lt_dlunknown=0; lt_dlno_uscore=1; lt_dlneed_uscore=2
   lt_status=$lt_dlunknown
   cat > conftest.$ac_ext <<EOF
-#line 10237 "configure"
+#line 10258 "configure"
 #include "confdefs.h"
 
 #if HAVE_DLFCN_H
@@ -22107,6 +22128,7 @@ ENABLE_CXX11!$ENABLE_CXX11$ac_delim
 ENABLE_OPTIMIZED!$ENABLE_OPTIMIZED$ac_delim
 ENABLE_PROFILING!$ENABLE_PROFILING$ac_delim
 DISABLE_ASSERTIONS!$DISABLE_ASSERTIONS$ac_delim
+ENABLE_WERROR!$ENABLE_WERROR$ac_delim
 ENABLE_EXPENSIVE_CHECKS!$ENABLE_EXPENSIVE_CHECKS$ac_delim
 EXPENSIVE_CHECKS!$EXPENSIVE_CHECKS$ac_delim
 DEBUG_RUNTIME!$DEBUG_RUNTIME$ac_delim
@@ -22117,7 +22139,6 @@ ENABLE_DOCS!$ENABLE_DOCS$ac_delim
 ENABLE_DOXYGEN!$ENABLE_DOXYGEN$ac_delim
 LLVM_ENABLE_THREADS!$LLVM_ENABLE_THREADS$ac_delim
 ENABLE_PTHREADS!$ENABLE_PTHREADS$ac_delim
-ENABLE_PIC!$ENABLE_PIC$ac_delim
 _ACEOF
 
   if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 97; then
@@ -22159,6 +22180,7 @@ _ACEOF
 ac_delim='%!_!# '
 for ac_last_try in false false false false false :; do
   cat >conf$$subs.sed <<_ACEOF
+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
@@ -22254,7 +22276,7 @@ LIBOBJS!$LIBOBJS$ac_delim
 LTLIBOBJS!$LTLIBOBJS$ac_delim
 _ACEOF
 
-  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 93; then
+  if test `sed -n "s/.*$ac_delim\$/X/p" conf$$subs.sed | grep -c X` = 94; then
     break
   elif $ac_last_try; then
     { { echo "$as_me:$LINENO: error: could not make $CONFIG_STATUS" >&5