diff --git a/android.py b/android.py
index 2c9e428..7c72643 100755
--- a/android.py
+++ b/android.py
@@ -332,7 +332,7 @@ def setup_android_cross_template(env: dict, opts: AndroidOpts, target: str, host
     ]
 
     # Runtime cross template
-    runtime.setup_runtime_cross_template(env, opts, 'android', target, host_triple, target_triple, device_target, 'llvm-llvm64', offsets_dumper_abi)
+    runtime.setup_runtime_cross_template(env, opts, 'android', target, host_triple, target_triple, device_target, 'llvm64', offsets_dumper_abi)
 
 
 def setup_android_cross_mxe_template(env: dict, opts: AndroidOpts, target: str, host_arch: str):
@@ -399,7 +399,7 @@ def setup_android_cross_mxe_template(env: dict, opts: AndroidOpts, target: str,
     env['_android-%s_CONFIGURE_FLAGS' % target] = CONFIGURE_FLAGS
 
     # Runtime cross template
-    runtime.setup_runtime_cross_template(env, opts, 'android', target, host_triple, target_triple, device_target, 'llvm-llvmwin64', offsets_dumper_abi)
+    runtime.setup_runtime_cross_template(env, opts, 'android', target, host_triple, target_triple, device_target, 'llvmwin64', offsets_dumper_abi)
 
 
 def make_standalone_toolchain(opts: AndroidOpts, target: str, api: str):
@@ -461,6 +461,7 @@ def make(opts: AndroidOpts, product: str, target: str):
     run_command('make', args=make_args, name='make')
     run_command('make', args=['-C', '%s/mono' % build_dir, 'install'], name='make install mono')
     run_command('make', args=['-C', '%s/support' % build_dir, 'install'], name='make install support')
+    run_command('make', args=['-C', '%s/data' % build_dir, 'install'], name='make install data')
 
     if opts.strip_libs and not is_cross(target):
         strip_libs(opts, product, target, env['ANDROID_API_VERSION'])
diff --git a/bcl.py b/bcl.py
index d1d8eac..e4de5b8 100755
--- a/bcl.py
+++ b/bcl.py
@@ -3,6 +3,7 @@
 
 import os
 import os.path
+import sys
 
 from os.path import join as path_join
 from options import *
@@ -141,9 +142,12 @@ def main(raw_args):
     opts = bcl_opts_from_args(args)
     products = args.product
 
-    for product in products:
-        action = actions[args.action]
-        action(opts, product)
+    try:
+        for product in products:
+            action = actions[args.action]
+            action(opts, product)
+    except BuildError as e:
+        sys.exit(e.message)
 
 
 if __name__ == '__main__':
diff --git a/desktop.py b/desktop.py
index cdfac69..16542ac 100755
--- a/desktop.py
+++ b/desktop.py
@@ -10,6 +10,7 @@ from options import *
 from os_utils import *
 import runtime
 
+
 # TODO: mono cross-compilers
 
 target_platforms = ['linux', 'windows', 'osx']
@@ -26,13 +27,42 @@ host_triples = {
     'osx': '%s-apple-darwin',
 }
 
+llvm_table = {
+    'linux': {
+        'i686': 'llvm32',
+        'x86_64': 'llvm64'
+    },
+    'windows': {
+        'i686': 'llvm32',
+        'x86_64': 'llvm64'
+    },
+    'osx': {
+        'x86_64': 'llvm64'
+    }
+}
+
 
 def is_cross_compiling(target_platform: str) -> bool:
     return (sys.platform == 'darwin' and target_platform != 'osx') or \
             (sys.platform in ['linux', 'linux2', 'cygwin'] and target_platform != 'linux')
 
 
-def setup_desktop_template(env: dict, opts: RuntimeOpts, product: str, target_platform: str, target: str):
+def get_osxcross_sdk(target, osxcross_bin):
+    osxcross_sdk = os.environ.get('OSXCROSS_SDK', 14)
+
+    name_fmt = path_join(osxcross_bin, target + '-apple-darwin%s-%s')
+
+    if not 'OSXCROSS_SDK' in os.environ and not os.path.isfile(name_fmt % (osxcross_sdk, 'ar')):
+        # Default 14 wasn't it, try 15
+        osxcross_sdk = 15
+
+    if not os.path.isfile(name_fmt % (osxcross_sdk, 'ar')):
+        raise BuildError('Specify a valid osxcross SDK with the environment variable \'OSXCROSS_SDK\'')
+
+    return osxcross_sdk
+
+
+def setup_desktop_template(env: dict, opts: DesktopOpts, product: str, target_platform: str, target: str):
     host_triple = host_triples[target_platform] % target
 
     CONFIGURE_FLAGS = [
@@ -52,37 +82,62 @@ def setup_desktop_template(env: dict, opts: RuntimeOpts, product: str, target_pl
 
         env['_%s-%s_PATH' % (product, target)] = mxe_bin
 
-        name_fmt = target + '-w64-mingw32-%s'
+        name_fmt = path_join(mxe_bin, target + '-w64-mingw32-%s')
 
-        env['_%s-%s_AR' % (product, target)] = path_join(mxe_bin, name_fmt % 'ar')
-        env['_%s-%s_AS' % (product, target)] = path_join(mxe_bin, name_fmt % 'as')
-        env['_%s-%s_CC' % (product, target)] = path_join(mxe_bin, name_fmt % 'gcc')
-        env['_%s-%s_CXX' % (product, target)] = path_join(mxe_bin, name_fmt % 'g++')
-        env['_%s-%s_DLLTOOL' % (product, target)] = path_join(mxe_bin, name_fmt % 'dlltool')
-        env['_%s-%s_LD' % (product, target)] = path_join(mxe_bin, name_fmt % 'ld')
-        env['_%s-%s_OBJDUMP' % (product, target)] = path_join(mxe_bin, name_fmt % 'objdump')
-        env['_%s-%s_RANLIB' % (product, target)] = path_join(mxe_bin, name_fmt % 'ranlib')
-        env['_%s-%s_STRIP' % (product, target)] = path_join(mxe_bin, name_fmt % 'strip')
+        env['_%s-%s_AR' % (product, target)] = name_fmt % 'ar'
+        env['_%s-%s_AS' % (product, target)] = name_fmt % 'as'
+        env['_%s-%s_CC' % (product, target)] = name_fmt % 'gcc'
+        env['_%s-%s_CXX' % (product, target)] = name_fmt % 'g++'
+        env['_%s-%s_DLLTOOL' % (product, target)] = name_fmt % 'dlltool'
+        env['_%s-%s_LD' % (product, target)] = name_fmt % 'ld'
+        env['_%s-%s_OBJDUMP' % (product, target)] = name_fmt % 'objdump'
+        env['_%s-%s_RANLIB' % (product, target)] = name_fmt % 'ranlib'
+        env['_%s-%s_STRIP' % (product, target)] = name_fmt % 'strip'
 
         CONFIGURE_FLAGS += [
             '--enable-static-gcc-libs'
         ]
+    elif target_platform == 'osx' and 'OSXCROSS_ROOT' in os.environ:
+        osxcross_root = os.environ['OSXCROSS_ROOT']
+        osxcross_bin = path_join(osxcross_root, 'target', 'bin')
+        osxcross_sdk = get_osxcross_sdk(target, osxcross_bin)
+
+        env['_%s-%s_PATH' % (product, target)] = osxcross_bin
+
+        name_fmt = path_join(osxcross_bin, target + ('-apple-darwin%s-' % osxcross_sdk) + '%s')
+
+        env['_%s-%s_AR' % (product, target)] = name_fmt % 'ar'
+        env['_%s-%s_AS' % (product, target)] = name_fmt % 'as'
+        env['_%s-%s_CC' % (product, target)] = name_fmt % 'cc'
+        env['_%s-%s_CXX' % (product, target)] = name_fmt % 'c++'
+        env['_%s-%s_LD' % (product, target)] = name_fmt % 'ld'
+        env['_%s-%s_RANLIB' % (product, target)] = name_fmt % 'ranlib'
+        env['_%s-%s_CMAKE' % (product, target)] = name_fmt % 'cmake'
+        env['_%s-%s_STRIP' % (product, target)] = name_fmt % 'strip'
     else:
         env['_%s-%s_CC' % (product, target)] = 'cc'
 
     env['_%s-%s_CONFIGURE_FLAGS' % (product, target)] = CONFIGURE_FLAGS
 
-    runtime.setup_runtime_template(env, opts, product, target, host_triple)
+    llvm = llvm_table[target_platform][target] if opts.with_llvm else ''
+
+    runtime.setup_runtime_template(env, opts, product, target, host_triple, llvm=llvm)
 
 
-def strip_libs(opts: RuntimeOpts, product: str, target_platform: str, target: str):
+def strip_libs(opts: DesktopOpts, product: str, target_platform: str, target: str):
     if is_cross_compiling(target_platform):
         if target_platform == 'windows':
             mxe_bin = path_join(opts.mxe_prefix, 'bin')
-            name_fmt = target + '-w64-mingw32-%s'
-            strip = path_join(mxe_bin, name_fmt % 'strip')
+            name_fmt = path_join(mxe_bin, target + '-w64-mingw32-%s')
+            strip = name_fmt % 'strip'
         elif target_platform == 'osx':
-            assert False # TODO osxcross
+            assert 'OSXCROSS_ROOT' in os.environ
+            osxcross_root = os.environ['OSXCROSS_ROOT']
+            osxcross_bin = path_join(osxcross_bin, 'target', 'bin')
+            osxcross_sdk = get_osxcross_sdk(target, osxcross_bin)
+
+            name_fmt = path_join(osxcross_bin, target + ('-apple-darwin%s-' % osxcross_sdk) + '%s')
+            strip = name_fmt % 'strip'
     else:
         strip = 'strip'
 
@@ -101,7 +156,7 @@ def strip_libs(opts: RuntimeOpts, product: str, target_platform: str, target: st
             run_command(strip, args=['--strip-unneeded'] + dll_files, name='strip')
 
 
-def configure(opts: RuntimeOpts, product: str, target_platform: str, target: str):
+def configure(opts: DesktopOpts, product: str, target_platform: str, target: str):
     env = {}
 
     setup_desktop_template(env, opts, product, target_platform, target)
@@ -112,7 +167,7 @@ def configure(opts: RuntimeOpts, product: str, target_platform: str, target: str
     runtime.run_configure(env, opts, product, target)
 
 
-def make(opts: RuntimeOpts, product: str, target_platform: str, target: str):
+def make(opts: DesktopOpts, product: str, target_platform: str, target: str):
     build_dir = path_join(opts.configure_dir, '%s-%s-%s' % (product, target, opts.configuration))
 
     make_args = ['-C', build_dir]
@@ -121,12 +176,13 @@ def make(opts: RuntimeOpts, product: str, target_platform: str, target: str):
     run_command('make', args=make_args, name='make')
     run_command('make', args=['-C', '%s/mono' % build_dir, 'install'], name='make install mono')
     run_command('make', args=['-C', '%s/support' % build_dir, 'install'], name='make install support')
+    run_command('make', args=['-C', '%s/data' % build_dir, 'install'], name='make install data')
 
     if opts.strip_libs:
         strip_libs(opts, product, target_platform, target)
 
 
-def clean(opts: RuntimeOpts, product: str, target_platform: str, target: str):
+def clean(opts: DesktopOpts, product: str, target_platform: str, target: str):
     rm_rf(
         path_join(opts.configure_dir, '%s-%s-%s' % (product, target, opts.configuration)),
         path_join(opts.configure_dir, '%s-%s-%s.config.cache' % (product, target, opts.configuration)),
@@ -153,6 +209,7 @@ def main(raw_args):
         target_platform_subparser = subparsers.add_parser(target_platform)
         target_platform_subparser.add_argument('action', choices=['configure', 'make', 'clean'])
         target_platform_subparser.add_argument('--target', choices=targets[target_platform], action='append', required=True)
+        target_platform_subparser.add_argument('--with-llvm', action='store_true', default=False, help=default_help)
 
     cmd_utils.add_runtime_arguments(parser, default_help)
 
@@ -162,14 +219,14 @@ def main(raw_args):
     input_target_platform = args.platform
     input_targets = args.target
 
-    opts = runtime_opts_from_args(args)
+    opts = desktop_opts_from_args(args)
 
     if not os.path.isdir(opts.mono_source_root):
         print('Mono sources directory not found: ' + opts.mono_source_root)
         sys.exit(1)
 
-    if is_cross_compiling(input_target_platform) and input_target_platform == 'osx':
-        raise RuntimeError('Cross-compiling for macOS is not currently supported') # TODO: osxcross
+    if input_target_platform == 'osx' and sys.platform != 'darwin' and not 'OSXCROSS_ROOT' in os.environ:
+        raise RuntimeError('The \'OSXCROSS_ROOT\' environment variable is required for cross-compiling to macOS')
 
     if is_cross_compiling(input_target_platform) and sys.platform == 'darwin':
         raise RuntimeError('Cross-compiling from macOS is not supported')
diff --git a/llvm.py b/llvm.py
index 5da7563..edb0bdf 100755
--- a/llvm.py
+++ b/llvm.py
@@ -8,8 +8,11 @@ from options import *
 from os_utils import *
 
 
-target_values = ['llvm64', 'llvmwin64']
-mxe_targets = {'llvmwin64': {'arch': 'x86_64', 'mxe': 'mxe-Win64'}}
+target_values = ['llvm32', 'llvm64', 'llvmwin32', 'llvmwin64']
+mxe_targets = {
+    'llvmwin32': {'arch': 'i686', 'mxe': 'mxe-Win32'},
+    'llvmwin64': {'arch': 'x86_64', 'mxe': 'mxe-Win64'}
+}
 
 
 def make(opts: BaseOpts, target: str):
@@ -55,6 +58,9 @@ def make(opts: BaseOpts, target: str):
             dst_file='%s/external/llvm/cmake/modules/%s.cmake' % (opts.mono_source_root, mxe)
         )
 
+    if target in ['llvm32', 'llvmwin32']:
+        CMAKE_ARGS += ['-DLLVM_BUILD_32_BITS=On']
+
     CMAKE_ARGS += [os.environ.get('llvm-%s_CMAKE_ARGS' % target, '')]
 
     make_args = [
@@ -108,9 +114,12 @@ def main(raw_args):
     opts = base_opts_from_args(args)
     targets = args.target
 
-    for target in targets:
-        action = { 'make': make, 'clean': clean }[args.action]
-        action(opts, target)
+    try:
+        for target in targets:
+            action = { 'make': make, 'clean': clean }[args.action]
+            action(opts, target)
+    except BuildError as e:
+        sys.exit(e.message)
 
 
 if __name__ == '__main__':
diff --git a/options.py b/options.py
index 54d4438..fbc2a39 100644
--- a/options.py
+++ b/options.py
@@ -31,6 +31,11 @@ class AndroidOpts(RuntimeOpts):
     toolchain_name_fmt: str = '%s-api%s-clang'
 
 
+@dataclass
+class DesktopOpts(RuntimeOpts):
+    with_llvm: bool
+
+
 @dataclass
 class BclOpts(BaseOpts):
     tests: bool
@@ -77,3 +82,10 @@ def bcl_opts_from_args(args):
         **vars(base_opts_from_args(args)),
         tests = args.tests
     )
+
+
+def desktop_opts_from_args(args):
+    return DesktopOpts(
+        **vars(runtime_opts_from_args(args)),
+        with_llvm = args.with_llvm
+    )
diff --git a/reference_assemblies.py b/reference_assemblies.py
index 5d05438..2669b73 100755
--- a/reference_assemblies.py
+++ b/reference_assemblies.py
@@ -1,5 +1,7 @@
 #!/usr/bin/python
 
+import sys
+
 from os.path import join as path_join
 from options import *
 from os_utils import *
@@ -53,8 +55,11 @@ def main(raw_args):
 
     opts = base_opts_from_args(args)
 
-    action = actions[args.action]
-    action(opts)
+    try:
+        action = actions[args.action]
+        action(opts)
+    except BuildError as e:
+        sys.exit(e.message)
 
 
 if __name__ == '__main__':
diff --git a/runtime.py b/runtime.py
index 27443d8..7b5b8ce 100644
--- a/runtime.py
+++ b/runtime.py
@@ -6,7 +6,7 @@ from options import RuntimeOpts
 from os_utils import *
 
 
-def setup_runtime_template(env: dict, opts: RuntimeOpts, product: str, target: str, host_triple: str):
+def setup_runtime_template(env: dict, opts: RuntimeOpts, product: str, target: str, host_triple: str, llvm: str=''):
     BITNESS = ''
     if any(s in host_triple for s in ['i686', 'i386']):
         BITNESS = '-m32'
@@ -83,6 +83,9 @@ def setup_runtime_template(env: dict, opts: RuntimeOpts, product: str, target: s
     CONFIGURE_FLAGS += env.get('_%s-%s_CONFIGURE_FLAGS' % (product, target), [])
     CONFIGURE_FLAGS += env.get('%s-%s_CONFIGURE_FLAGS' % (product, target), [])
 
+    if llvm:
+        CONFIGURE_FLAGS += ['--with-llvm=%s/llvm-%s' % (opts.install_dir, llvm)]
+
     env['_runtime_%s-%s_AC_VARS' % (product, target)] = AC_VARS
     env['_runtime_%s-%s_CONFIGURE_ENVIRONMENT' % (product, target)] = CONFIGURE_ENVIRONMENT
     env['_runtime_%s-%s_CONFIGURE_FLAGS' % (product, target)] = CONFIGURE_FLAGS
@@ -93,7 +96,7 @@ def setup_runtime_cross_template(env: dict, opts: RuntimeOpts, product: str, tar
     CONFIGURE_FLAGS = [
         '--target=%s' % target_triple,
         '--with-cross-offsets=%s.h' % target_triple,
-        '--with-llvm=%s/%s' % (opts.install_dir, llvm)
+        '--with-llvm=%s/llvm-%s' % (opts.install_dir, llvm)
     ]
 
     env['_cross-runtime_%s-%s_CONFIGURE_FLAGS' % (product, target)] = CONFIGURE_FLAGS
diff --git a/wasm.py b/wasm.py
index 50c0d8f..e6f65b7 100755
--- a/wasm.py
+++ b/wasm.py
@@ -137,6 +137,7 @@ def make(opts: RuntimeOpts, product: str, target: str):
     run_command('emmake', args=['make'] + make_args, env=make_env, name='make')
 
     run_command('make', args=['-C', '%s/mono' % build_dir, 'install'], name='make install mono')
+    run_command('make', args=['-C', '%s/data' % build_dir, 'install'], name='make install data')
 
     # Copy support headers