Make unit-at-a-time on by default to match the behavior of llvm-gcc.


git-svn-id: https://llvm.org/svn/llvm-project/llvm/trunk@79698 91177308-0d34-0410-b5e6-96231b3b80d8
diff --git a/tools/opt/opt.cpp b/tools/opt/opt.cpp
index e9c239a..40f3fb9 100644
--- a/tools/opt/opt.cpp
+++ b/tools/opt/opt.cpp
@@ -107,7 +107,8 @@
 
 static cl::opt<bool>
 UnitAtATime("funit-at-a-time",
-            cl::desc("Enable IPO. This is same as llvm-gcc's -funit-at-a-time"));
+            cl::desc("Enable IPO. This is same as llvm-gcc's -funit-at-a-time"),
+	    cl::init(true));
 
 static cl::opt<bool>
 DisableSimplifyLibCalls("disable-simplify-libcalls",