diff --git a/.gitignore b/.gitignore
index 9f111ebc..d996ca57 100644
--- a/.gitignore
+++ b/.gitignore
@@ -5,6 +5,7 @@ wren
 
 # Intermediate files.
 build/
+deps/
 .sass-cache/
 
 # I leave a temporary Wren script at the top level so that I can quickly test
diff --git a/Makefile b/Makefile
index 40c2bb68..7814c8df 100644
--- a/Makefile
+++ b/Makefile
@@ -4,18 +4,16 @@
 
 # Executables are built to bin/. Libraries are built to lib/.
 
-LIBUV := build/libuv/out/Release/libuv.a
-
 # A normal, optimized release build for the current CPU architecture.
-release: $(LIBUV)
+release:
 	@ $(MAKE) -f script/wren.mk
 	@ cp bin/wren wren # For convenience, copy the interpreter to the top level.
 
 # A debug build for the current architecture.
-debug: $(LIBUV)
+debug:
 	@ $(MAKE) -f script/wren.mk MODE=debug
 
-# A release build of just the VM. Does not require libuv.
+# A release build of just the VM.
 vm:
 	@ $(MAKE) -f script/wren.mk vm
 
@@ -32,16 +30,17 @@ all: debug release
 	@ $(MAKE) -f script/wren.mk MODE=debug ARCH=64
 	@ $(MAKE) -f script/wren.mk MODE=debug LANG=cpp ARCH=64
 
-# Download and build libuv to a static library.
-$(LIBUV): script/libuv.py
-	@ ./script/libuv.py
-
-# Remove all build outputs and intermediate files.
+# Remove all build outputs and intermediate files. Does not remove downloaded
+# dependencies. Use cleanall for that.
 clean:
 	@ rm -rf bin
 	@ rm -rf build
 	@ rm -rf lib
 
+# Remove all build outputs, intermediate files, and downloaded dependencies.
+cleanall: clean
+	@ rm -rf deps
+
 # Run the tests against the debug build of Wren.
 test: debug
 	@ $(MAKE) -f script/wren.mk MODE=debug test
diff --git a/script/libuv.py b/script/libuv.py
index 17aa8693..e95e6913 100755
--- a/script/libuv.py
+++ b/script/libuv.py
@@ -12,7 +12,7 @@ import subprocess
 import sys
 
 LIB_UV_VERSION = "v1.6.1"
-LIB_UV_DIR = "build/libuv"
+LIB_UV_DIR = "deps/libuv"
 
 def ensure_dir(dir):
   """Creates dir if not already there."""
@@ -22,6 +22,7 @@ def ensure_dir(dir):
 
   os.makedirs(dir)
 
+
 def remove_dir(dir):
   """Recursively removes dir."""
 
@@ -31,10 +32,11 @@ def remove_dir(dir):
     subprocess.check_call(
         ['cmd', '/c', 'rd', '/s', '/q', dir.replace('/', '\\')])
   else:
-    shutil.rmtree(LIB_UV_DIR)
+    shutil.rmtree(dir)
+
 
 def download_libuv():
-  """Clones libuv into build/libuv and checks out the right version."""
+  """Clones libuv into deps/libuv and checks out the right version."""
 
   # Delete it if already there so we ensure we get the correct version if the
   # version number in this script changes.
@@ -42,7 +44,7 @@ def download_libuv():
     print("Cleaning output directory...")
     remove_dir(LIB_UV_DIR)
 
-  ensure_dir("build")
+  ensure_dir("deps")
 
   print("Cloning libuv...")
   run([
@@ -90,7 +92,7 @@ def build_libuv_mac():
   ])
 
 
-def build_libuv_linux():
+def build_libuv_linux(arch):
   run(["python", "gyp_uv.py", "-f", "make"], cwd=LIB_UV_DIR)
   run(["make", "-C", "out", "BUILDTYPE=Release"], cwd=LIB_UV_DIR)
 
@@ -99,17 +101,24 @@ def build_libuv_windows():
   run(["cmd", "/c", "vcbuild.bat", "release"], cwd=LIB_UV_DIR)
 
 
-def build_libuv():
+def build_libuv(arch, out):
   if platform.system() == "Darwin":
     build_libuv_mac()
   elif platform.system() == "Linux":
-    build_libuv_linux()
-  elif platform.system() == "Windows":
+    build_libuv_linux(arch)
+  elif platform.system(arch) == "Windows":
     build_libuv_windows()
   else:
     print("Unsupported platform: " + platform.system())
     sys.exit(1)
 
+  # Copy the build library to the build directory for Mac and Linux where we
+  # support building for multiple architectures.
+  if platform.system() != "Windows":
+    ensure_dir(os.path.dirname(out))
+    shutil.copyfile(
+      os.path.join(LIB_UV_DIR, "out", "Release", "libuv.a"), out)
+
 
 def run(args, cwd=None):
   """Spawn a process to invoke [args] and mute its output."""
@@ -117,8 +126,29 @@ def run(args, cwd=None):
 
 
 def main():
-  download_libuv()
-  build_libuv()
+  expect_usage(len(sys.argv) >= 2)
+
+  if sys.argv[1] == "download":
+    download_libuv()
+  elif sys.argv[1] == "build":
+    expect_usage(len(sys.argv) <= 3)
+    arch = ""
+    if len(sys.argv) == 3:
+      arch = sys.argv[2]
+
+    out = os.path.join("build", "libuv" + arch + ".a")
+
+    build_libuv(arch, out)
+  else:
+    expect_usage(false)
+
+
+def expect_usage(condition):
+  if (condition): return
+
+  print("Usage: libuv.py download")
+  print("       libuv.py build [-32|-64]")
+  sys.exit(1)
 
 
 main()
diff --git a/script/wren.mk b/script/wren.mk
index af7c2a30..2feb61cd 100644
--- a/script/wren.mk
+++ b/script/wren.mk
@@ -60,12 +60,14 @@ ifeq ($(ARCH),32)
 	C_OPTIONS += -m32
 	WREN := $(WREN)-32
 	BUILD_DIR := $(BUILD_DIR)-32
+	LIBUV_ARCH := -32
 endif
 
 ifeq ($(ARCH),64)
 	C_OPTIONS += -m64
 	WREN := $(WREN)-64
 	BUILD_DIR := $(BUILD_DIR)-64
+	LIBUV_ARCH := -64
 endif
 
 # Some platform-specific workarounds. Note that we use "gcc" explicitly in the
@@ -107,8 +109,8 @@ MODULE_OBJECTS := $(addprefix $(BUILD_DIR)/module/, $(notdir $(MODULE_SOURCES:.c
 VM_OBJECTS     := $(addprefix $(BUILD_DIR)/vm/, $(notdir $(VM_SOURCES:.c=.o)))
 TEST_OBJECTS   := $(patsubst test/api/%.c, $(BUILD_DIR)/test/%.o, $(TEST_SOURCES))
 
-LIBUV_DIR := build/libuv
-LIBUV     := $(LIBUV_DIR)/out/Release/libuv.a
+LIBUV_DIR := deps/libuv
+LIBUV     := build/libuv$(LIBUV_ARCH).a
 
 # Flags needed to compile source files for the CLI, including the modules and
 # API tests.
@@ -131,51 +133,61 @@ test: $(BUILD_DIR)/test/$(WREN)
 
 # Command-line interpreter.
 bin/$(WREN): $(CLI_OBJECTS) $(MODULE_OBJECTS) $(VM_OBJECTS) $(LIBUV)
-	@printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS)"
-	@mkdir -p bin
-	@$(CC) $(CFLAGS) $^ -o $@ -lm $(LIBUV_LIBS)
+	@ printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS)"
+	@ mkdir -p bin
+	@ $(CC) $(CFLAGS) $^ -o $@ -lm $(LIBUV_LIBS)
 
 # Static library.
 lib/lib$(WREN).a: $(VM_OBJECTS)
-	@printf "%10s %-30s %s\n" $(AR) $@ "rcu"
-	@mkdir -p lib
-	@$(AR) rcu $@ $^
+	@ printf "%10s %-30s %s\n" $(AR) $@ "rcu"
+	@ mkdir -p lib
+	@ $(AR) rcu $@ $^
 
 # Shared library.
 lib/lib$(WREN).$(SHARED_EXT): $(VM_OBJECTS)
-	@printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS) $(SHARED_LIB_FLAGS)"
-	@mkdir -p lib
-	@$(CC) $(CFLAGS) -shared $(SHARED_LIB_FLAGS) -o $@ $^
+	@ printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS) $(SHARED_LIB_FLAGS)"
+	@ mkdir -p lib
+	@ $(CC) $(CFLAGS) -shared $(SHARED_LIB_FLAGS) -o $@ $^
 
 # Test executable.
 $(BUILD_DIR)/test/$(WREN): $(TEST_OBJECTS) $(MODULE_OBJECTS) $(VM_OBJECTS) \
 		$(BUILD_DIR)/cli/io.o $(BUILD_DIR)/cli/vm.o $(LIBUV)
-	@printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS)"
-	@mkdir -p $(BUILD_DIR)/test
-	@$(CC) $(CFLAGS) $^ -o $@ -lm $(LIBUV_LIBS)
+	@ printf "%10s %-30s %s\n" $(CC) $@ "$(C_OPTIONS)"
+	@ mkdir -p $(BUILD_DIR)/test
+	@ $(CC) $(CFLAGS) $^ -o $@ -lm $(LIBUV_LIBS)
 
 # CLI object files.
-$(BUILD_DIR)/cli/%.o: src/cli/%.c $(CLI_HEADERS) $(MODULE_HEADERS) $(VM_HEADERS)
-	@printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
-	@mkdir -p $(BUILD_DIR)/cli
-	@$(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
+$(BUILD_DIR)/cli/%.o: src/cli/%.c $(CLI_HEADERS) $(MODULE_HEADERS) \
+		$(VM_HEADERS) $(LIBUV)
+	@ printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
+	@ mkdir -p $(BUILD_DIR)/cli
+	@ $(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
 
 # Module object files.
-$(BUILD_DIR)/module/%.o: src/module/%.c $(CLI_HEADERS) $(MODULE_HEADERS) $(VM_HEADERS)
-	@printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
-	@mkdir -p $(BUILD_DIR)/module
-	@$(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
+$(BUILD_DIR)/module/%.o: src/module/%.c $(CLI_HEADERS) $(MODULE_HEADERS) \
+		$(VM_HEADERS) $(LIBUV)
+	@ printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
+	@ mkdir -p $(BUILD_DIR)/module
+	@ $(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
 
 # VM object files.
 $(BUILD_DIR)/vm/%.o: src/vm/%.c $(VM_HEADERS)
-	@printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
-	@mkdir -p $(BUILD_DIR)/vm
-	@$(CC) -c $(CFLAGS) -Isrc/include -o $@ $(FILE_FLAG) $<
+	@ printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
+	@ mkdir -p $(BUILD_DIR)/vm
+	@ $(CC) -c $(CFLAGS) -Isrc/include -o $@ $(FILE_FLAG) $<
 
 # Test object files.
-$(BUILD_DIR)/test/%.o: test/api/%.c $(MODULE_HEADERS) $(VM_HEADERS)
-	@printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
-	@mkdir -p $(dir $@)
-	@$(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
+$(BUILD_DIR)/test/%.o: test/api/%.c $(MODULE_HEADERS) $(VM_HEADERS) $(LIBUV)
+	@ printf "%10s %-30s %s\n" $(CC) $< "$(C_OPTIONS)"
+	@ mkdir -p $(dir $@)
+	@ $(CC) -c $(CFLAGS) $(CLI_FLAGS) -o $@ $(FILE_FLAG) $<
+
+# Download libuv.
+$(LIBUV_DIR)/build/gyp/gyp: script/libuv.py
+	@ ./script/libuv.py download
+
+# Build libuv to a static library.
+$(LIBUV): $(LIBUV_DIR)/build/gyp/gyp script/libuv.py
+	@ ./script/libuv.py build $(LIBUV_ARCH)
 
 .PHONY: all cli test vm
diff --git a/test/benchmark/delta_blue.wren b/test/benchmark/delta_blue.wren
index 4c88d6db..af57d8a2 100644
--- a/test/benchmark/delta_blue.wren
+++ b/test/benchmark/delta_blue.wren
@@ -708,4 +708,3 @@ for (i in 0...20) {
 
 IO.print(total)
 IO.print("elapsed: ", IO.clock - start)
-