diff --git a/llvm/utils/gn/gn.py b/llvm/utils/gn/gn.py
--- a/llvm/utils/gn/gn.py
+++ b/llvm/utils/gn/gn.py
@@ -33,12 +33,23 @@
     print('follow https://gn.googlesource.com/gn/#getting-started')
     return 1
 
+def system_binary_available(binary_name):
+    if sys.platform == 'win32':
+        if subprocess.call(['WHERE', '/q', binary_name],
+                           stdout=open(os.devnull, 'w'),
+                           stderr=subprocess.STDOUT) == 0:
+            return True
+    elif os.name == 'posix':
+        if subprocess.call(['which', binary_name],
+                           stdout=open(os.devnull, 'w'),
+                           stderr=subprocess.STDOUT) == 0:
+            return True
+    return False
 
 def main():
     # Find real gn executable.
     gn = 'gn'
-    if subprocess.call([gn, '--version'], stdout=open(os.devnull, 'w'),
-                                          stderr=subprocess.STDOUT) != 0:
+    if not system_binary_available(gn):
         # Not on path. See if get.py downloaded a prebuilt binary and run that
         # if it's there, or suggest to run get.py if it isn't.
         platform = get_platform()