Index: lib/Transforms/Scalar/LowerAtomic.cpp
===================================================================
--- lib/Transforms/Scalar/LowerAtomic.cpp
+++ lib/Transforms/Scalar/LowerAtomic.cpp
@@ -86,6 +86,12 @@
     Res = Builder.CreateSelect(Builder.CreateICmpULT(Orig, Val),
                                Orig, Val);
     break;
+  case AtomicRMWInst::FAdd:
+    Res = Builder.CreateFAdd(Orig, Val);
+    break;
+  case AtomicRMWInst::FSub:
+    Res = Builder.CreateFSub(Orig, Val);
+    break;
   }
   Builder.CreateStore(Res, Ptr);
   RMWI->replaceAllUsesWith(Orig);
Index: test/Transforms/LowerAtomic/atomic-load.ll
===================================================================
--- test/Transforms/LowerAtomic/atomic-load.ll
+++ test/Transforms/LowerAtomic/atomic-load.ll
@@ -35,3 +35,25 @@
   ret i8 %j
 ; CHECK: ret i8 [[INST]]
 }
+
+define float @fadd() {
+; CHECK-LABEL: @fadd(
+  %i = alloca float
+  %j = atomicrmw fadd float* %i, float 42.0 monotonic
+; CHECK: [[INST:%[a-z0-9]+]] = load
+; CHECK-NEXT: fadd
+; CHECK-NEXT: store
+  ret float %j
+; CHECK: ret float [[INST]]
+}
+
+define float @fsub() {
+; CHECK-LABEL: @fsub(
+  %i = alloca float
+  %j = atomicrmw fsub float* %i, float 42.0 monotonic
+; CHECK: [[INST:%[a-z0-9]+]] = load
+; CHECK-NEXT: fsub
+; CHECK-NEXT: store
+  ret float %j
+; CHECK: ret float [[INST]]
+}