diff --git a/llvm/lib/Support/Windows/Program.inc b/llvm/lib/Support/Windows/Program.inc
--- a/llvm/lib/Support/Windows/Program.inc
+++ b/llvm/lib/Support/Windows/Program.inc
@@ -532,8 +532,13 @@
 
 bool llvm::sys::commandLineFitsWithinSystemLimits(StringRef Program,
                                                   ArrayRef<StringRef> Args) {
-  // The documented max length of the command line passed to CreateProcess.
-  static const size_t MaxCommandStringLength = 32768;
+  // In the documentation on CreateProcessW:
+  // https://docs.microsoft.com/en-us/windows/win32/api/processthreadsapi/nf-processthreadsapi-createprocessw
+  // it is stated that the argument lpCommandLine has restriction:
+  //
+  //    The maximum length of this string is 32,767 characters, including the
+  //    Unicode terminating null character.
+  static const size_t MaxCommandStringLength = 32767;
   SmallVector<StringRef, 8> FullArgs;
   FullArgs.push_back(Program);
   FullArgs.append(Args.begin(), Args.end());