Index: lib/Support/Unix/Program.inc
===================================================================
--- lib/Support/Unix/Program.inc
+++ lib/Support/Unix/Program.inc
@@ -448,13 +448,13 @@
     return true;
 
   // Conservatively account for space required by environment variables.
-  ArgMax /= 2;
+  long HalfArgMax = ArgMax / 2;
 
   size_t ArgLength = 0;
   for (ArrayRef<const char*>::iterator I = Args.begin(), E = Args.end();
        I != E; ++I) {
     ArgLength += strlen(*I) + 1;
-    if (ArgLength > size_t(ArgMax)) {
+    if (ArgLength > size_t(HalfArgMax)) {
       return false;
     }
   }