--- a/toolkit/moz.configure
+++ b/toolkit/moz.configure
@@ -618,31 +618,24 @@ def building_stylo_bindgen(stylo_config,
 # platforms.
 @depends(host)
 @imports('which')
 @imports('os')
 @imports('subprocess')
 def llvm_config_paths(host):
     llvm_config_progs = [
         'llvm-config-4.0',
-        'llvm-config-mp-4.0',   # MacPorts's chosen naming scheme
+        'llvm-config-mp-4.0',   # MacPorts' chosen naming scheme.
         'llvm-config40',
         'llvm-config-3.9',
         'llvm-config39',
         'llvm-config',
     ]
 
-    # Also add in the location to which `mach bootstrap` installs clang.
-    mozbuild_state_dir = os.environ.get('MOZBUILD_STATE_PATH',
-                                        os.path.expanduser(os.path.join('~', '.mozbuild')))
-    bootstrap_llvm_config = os.path.join(mozbuild_state_dir, 'clang', 'bin', 'llvm-config')
-
-    llvm_config_progs.append(bootstrap_llvm_config)
-
-    # Homebrew on OS X doesn't make clang available on PATH, so we have to
+    # Homebrew on macOS doesn't make clang available on PATH, so we have to
     # look for it in non-standard places.
     if host.kernel == 'Darwin':
         try:
             brew = which.which('brew')
             brew_config = subprocess.check_output([brew, 'config']).strip()
 
             for line in brew_config.splitlines():
                 if line.startswith('HOMEBREW_PREFIX'):
@@ -650,16 +643,24 @@ def llvm_config_paths(host):
                     prefix = fields[1] if len(fields) == 2 else ''
                     path = ['opt', 'llvm', 'bin', 'llvm-config']
                     llvm_config_progs.append(os.path.join(prefix, *path))
                     break
         except which.WhichError:
             # Homebrew not installed, which is fine.
             pass
 
+    # Also add in the location to which `mach bootstrap` or
+    # `mach artifact toolchain` installs clang.
+    mozbuild_state_dir = os.environ.get('MOZBUILD_STATE_PATH',
+                                        os.path.expanduser(os.path.join('~', '.mozbuild')))
+    bootstrap_llvm_config = os.path.join(mozbuild_state_dir, 'clang', 'bin', 'llvm-config')
+
+    llvm_config_progs.append(bootstrap_llvm_config)
+
     return llvm_config_progs
 
 llvm_config = check_prog('LLVM_CONFIG', llvm_config_paths,
                          when=building_stylo_bindgen,
                          what='llvm-config', allow_missing=True)
 
 with only_when(building_stylo_bindgen):
     option('--with-libclang-path', nargs=1,