diff --git a/lib/Transforms/InstCombine/InstCombineAddSub.cpp b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
index 99f0f1f08d7..e80d6a9ee39 100644
--- a/lib/Transforms/InstCombine/InstCombineAddSub.cpp
+++ b/lib/Transforms/InstCombine/InstCombineAddSub.cpp
@@ -32,7 +32,7 @@ namespace {
   ///
   class FAddendCoef {
   public:
-    // The constructor has to initialize a APFloat, which is uncessary for
+    // The constructor has to initialize a APFloat, which is unnecessary for
     // most addends which have coefficient either 1 or -1. So, the constructor
     // is expensive. In order to avoid the cost of the constructor, we should
     // reuse some instances whenever possible. The pre-created instances