diff --git a/include/llvm/ADT/APInt.h b/include/llvm/ADT/APInt.h
index b08564ca733..d8ed2224985 100644
--- a/include/llvm/ADT/APInt.h
+++ b/include/llvm/ADT/APInt.h
@@ -561,7 +561,15 @@ public:
   /// Performs logical negation operation on this APInt.
   /// @returns true if *this is zero, false otherwise.
   /// @brief Logical negation operator.
-  bool operator!() const;
+  bool operator!() const {
+    if (isSingleWord())
+      return !VAL;
+
+    for (unsigned i = 0; i != getNumWords(); ++i)
+      if (pVal[i])
+        return false;
+    return true;
+  }
 
   /// @}
   /// @name Assignment Operators
diff --git a/lib/Support/APInt.cpp b/lib/Support/APInt.cpp
index e5423f153c3..c5713a0eb17 100644
--- a/lib/Support/APInt.cpp
+++ b/lib/Support/APInt.cpp
@@ -457,16 +457,6 @@ APInt APInt::XorSlowCase(const APInt& RHS) const {
   return APInt(val, getBitWidth()).clearUnusedBits();
 }
 
-bool APInt::operator !() const {
-  if (isSingleWord())
-    return !VAL;
-
-  for (unsigned i = 0; i < getNumWords(); ++i)
-    if (pVal[i])
-      return false;
-  return true;
-}
-
 APInt APInt::operator*(const APInt& RHS) const {
   assert(BitWidth == RHS.BitWidth && "Bit widths must be the same");
   if (isSingleWord())