diff --git a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
index 41e10ba858149632e1e053fa120ff162a57dd6d8..0d3c5c7bdc985bcc29fb421b7ecba750ee1063a5 100644
--- a/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
+++ b/llvm/lib/Transforms/Scalar/MemCpyOptimizer.cpp
@@ -517,9 +517,6 @@ bool MemCpyOpt::processStore(StoreInst *SI, BasicBlock::iterator &BBI) {
 }
 
 bool MemCpyOpt::processMemSet(MemSetInst *MSI, BasicBlock::iterator &BBI) {
-  // Temporarily disable this.
-  return false;
-  
   // See if there is another memset or store neighboring this memset which
   // allows us to widen out the memset to do a single larger store.
   if (isa<ConstantInt>(MSI->getLength()) && !MSI->isVolatile())
diff --git a/llvm/test/Transforms/MemCpyOpt/form-memset.ll b/llvm/test/Transforms/MemCpyOpt/form-memset.ll
index 86fe6c4abd60bf6bffa085cd8017be6427b535ed..1ac97e9e6b91fbea0d365ab8ba8b7aad6d87e4e3 100644
--- a/llvm/test/Transforms/MemCpyOpt/form-memset.ll
+++ b/llvm/test/Transforms/MemCpyOpt/form-memset.ll
@@ -202,10 +202,9 @@ entry:
   %arrayidx = getelementptr inbounds i32* %P, i64 1
   store i32 0, i32* %arrayidx, align 4
   ret void
-  ; FIXME: Disabled.
 ; CHECK: @test5
-; CHECK: store
-; CHECK-NOT: call void @llvm.memset.p0i8.i64(i8* %1, i8 0, i64 15, i32 4, i1 false)
+; CHECK-NOT: store
+; CHECK: call void @llvm.memset.p0i8.i64(i8* %1, i8 0, i64 15, i32 4, i1 false)
 }
 
 ;; Memset followed by memset.
@@ -218,6 +217,6 @@ entry:
   tail call void @llvm.memset.p0i8.i64(i8* %1, i8 0, i64 12, i32 1, i1 false)
   ret void
 ; CHECK: @test6
-; CHECK-NOT: call void @llvm.memset.p0i8.i64(i8* %2, i8 0, i64 24, i32 1, i1 false)
+; CHECK: call void @llvm.memset.p0i8.i64(i8* %2, i8 0, i64 24, i32 1, i1 false)
 }