Emscripten fatal error: string not found

I am compiling a c++ app for use on the web with emscripten. The app uses the stdlib and needs to use c++11

I can compile my code just fine with clang. Here is the makefile:

LIB := include/simulator
SIM_LIB :=  include/simulator
CLANG := clang++ -std=c++11 -stdlib=libc++ -c -g -I $(LIB)
LINK := clang++ `sdl-config --cflags --libs` -lSDL_ttf -lSDL_image -lSDL_gfx -std=c++11 -stdlib=libc++ -v -g -I $(LIB)
SRC := src
BIN := bin
TEST := tests

simulatormake: main.o sim.o world.o robot.o spiking_nnet.o distance_sensor.o garden.o
    $(LINK) -o run sim.o world.o robot.o spiking_nnet.o distance_sensor.o garden.o $(SRC)/main.cpp


sim.o: $(SRC)/sim.cpp $(SIM_LIB)/sim.h $(SIM_LIB)/drawable.h $(SIM_LIB)/world.h
    $(CLANG) $(SRC)/sim.cpp 

robot.o: $(SRC)/robot.cpp $(SIM_LIB)/robot.h $(SIM_LIB)/point.h $(SIM_LIB)/drawable.h $(SIM_LIB)/modulo.h $(SIM_LIB)/distance_sensor.h $(SIM_LIB)/agent.h $(SIM_LIB)/world.h $(SIM_LIB)/spiking_nnet.h
    $(CLANG) $(SRC)/robot.cpp

garden.o: $(SRC)/garden.cpp $(SIM_LIB)/garden.h $(SIM_LIB)/point.h $(SIM_LIB)/drawable.h
    $(CLANG) $(SRC)/garden.cpp

world.o: $(SRC)/world.cpp $(SIM_LIB)/world.h $(SIM_LIB)/robot.h $(SIM_LIB)/garden.h $(SIM_LIB)/point.h $(SIM_LIB)/drawable.h
    $(CLANG) $(SRC)/world.cpp

spiking_nnet.o: $(SRC)/spiking_nnet.cpp $(SIM_LIB)/spiking_nnet.h
    $(CLANG) $(SRC)/spiking_nnet.cpp

distance_sensor.o: $(SRC)/distance_sensor.cpp $(SIM_LIB)/distance_sensor.h $(SIM_LIB)/modulo.h $(SIM_LIB)/drawable.h $(SIM_LIB)/agent.h
    $(CLANG) $(SRC)/distance_sensor.cpp

agent.h: drawable.h

drawable.h: point.h

robot.h: point.h drawable.h

point.h: 

test_sim: sim.o world.o distance_sensor.o robot.o spiking_nnet.o garden.o
    $(LINK) -o $(BIN)/test_sim sim.o world.o distance_sensor.o spiking_nnet.o robot.o garden.o $(TEST)/test_sim.cpp
    gdb bin/test_sim

test_robot: robot.o sim.o world.o distance_sensor.o garden.o spiking_nnet.o
    $(LINK) -o $(BIN)/test_robot robot.o world.o distance_sensor.o garden.o spiking_nnet.o $(TEST)/test_robot.cpp sim.o
    gdb bin/test_robot

test_garden: garden.o
    $(LINK) -o $(BIN)/test_garden garden.o $(TEST)/test_garden.cpp
    gdb bin/test_garden

test_world: robot.o world.o sim.o garden.o distance_sensor.o spiking_nnet.o
    $(LINK) -o $(BIN)/test_world world.o robot.o sim.o garden.o distance_sensor.o spiking_nnet.o  $(TEST)/test_world.cpp
    gdb bin/test_world

test_spiking_nnet: spiking_nnet.o sim.o
    $(LINK) -o $(BIN)/test_spiking_nnet $(TEST)/test_spiking_nnet.cpp spiking_nnet.o sim.o  
    gdb bin/test_spiking_nnet

test_distance_sensor: distance_sensor.o robot.o garden.o
    $(LINK) -o $(BIN)/test_distance_sensor $(TEST)/test_distance_sensor.cpp distance_sensor.o  robot.o garden.o
    gdb bin/test_distance_sensor

clean:
    rm *.o

When I run emmake make I get the following error:

include/simulator/sim.h:5:10: fatal error: 'string' file not found
#include <string>
         ^
1 error generated.
make: *** [simulatormake] Error 1