diff --git a/llvm/lib/Analysis/InlineCost.cpp b/llvm/lib/Analysis/InlineCost.cpp
index a6bf4a8..bc1ecd2 100644
--- a/llvm/lib/Analysis/InlineCost.cpp
+++ b/llvm/lib/Analysis/InlineCost.cpp
@@ -797,9 +797,33 @@
     FiftyPercentVectorBonus = Threshold;
     TenPercentVectorBonus = Threshold / 2;
 
-    // Subtract off one instruction per call argument as those will be free after
-    // inlining.
-    Cost -= CS.arg_size() * InlineConstants::InstrCost;
+    // Give out bonuses per argument, as the instructions setting them up will
+    // be gone after inlining.
+    for (unsigned I = 0, E = CS.arg_size(); I != E; ++I) {
+      if (TD && CS.isByValArgument(I)) {
+        // We approximate the number of loads and stores needed by dividing the
+        // size of the byval type by the target's pointer size.
+        PointerType *PTy = cast<PointerType>(CS.getArgument(I)->getType());
+        unsigned TypeSize = TD->getTypeSizeInBits(PTy->getElementType());
+        unsigned PointerSize = TD->getPointerSizeInBits();
+        // Ceiling division.
+        unsigned NumStores = (TypeSize + PointerSize - 1) / PointerSize;
+
+        // If it generates more than 8 stores it is likely to be expanded as an
+        // inline memcpy so we take that as an upper bound. Otherwise we assume
+        // one load and one store per word copied.
+        // FIXME: The maxStoresPerMemcpy setting from the target should be used
+        // here instead of a magic number of 8, but it's not available via
+        // TargetData.
+        NumStores = std::min(NumStores, 8U);
+
+        Cost -= 2 * NumStores * InlineConstants::InstrCost;
+      } else {
+        // For non-byval arguments subtract off one instruction per call
+        // argument.
+        Cost -= InlineConstants::InstrCost;
+      }
+    }
 
     // If there is only one call of the function, and it has internal linkage,
     // the cost of inlining it drops dramatically.