diff --git a/ui/build/config_darwin.go b/ui/build/config_darwin.go
new file mode 100644
index 0000000..480d8d1
--- /dev/null
+++ b/ui/build/config_darwin.go
@@ -0,0 +1,40 @@
+// Copyright 2019 Google Inc. All rights reserved.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package build
+
+import (
+	"encoding/binary"
+	"syscall"
+)
+
+func detectTotalRAM(ctx Context) uint64 {
+	s, err := syscall.Sysctl("hw.memsize")
+	if err != nil {
+		ctx.Printf("Failed to get system memory size: %s")
+		return 0
+	}
+
+	// syscall.Sysctl assumes that the return value is a string and trims the last byte if it is 0.
+	if len(s) == 7 {
+		s += "\x00"
+	}
+
+	if len(s) != 8 {
+		ctx.Printf("Failed to get system memory size, returned %d bytes, 8", len(s))
+		return 0
+	}
+
+	return binary.LittleEndian.Uint64([]byte(s))
+}