diff --git a/cc/check.go b/cc/check.go
new file mode 100644
index 0000000..e6a8036
--- /dev/null
+++ b/cc/check.go
@@ -0,0 +1,96 @@
+// Copyright 2016 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 cc
+
+// This file contains utility functions to check for bad or illegal cflags
+// specified by a module
+
+import (
+	"path/filepath"
+	"strings"
+)
+
+// Check for invalid c/conly/cpp/asflags and suggest alternatives. Only use this
+// for flags explicitly passed by the user, since these flags may be used internally.
+func CheckBadCompilerFlags(ctx ModuleContext, prop string, flags []string) {
+	for _, flag := range flags {
+		flag = strings.TrimSpace(flag)
+
+		if !strings.HasPrefix(flag, "-") {
+			ctx.PropertyErrorf(prop, "Flag `%s` must start with `-`", flag)
+		} else if strings.HasPrefix(flag, "-I") || strings.HasPrefix(flag, "-isystem") {
+			ctx.PropertyErrorf(prop, "Bad flag `%s`, use local_include_dirs or include_dirs instead", flag)
+		} else if inList(flag, illegalFlags) {
+			ctx.PropertyErrorf(prop, "Illegal flag `%s`", flag)
+		} else if strings.Contains(flag, " ") {
+			args := strings.Split(flag, " ")
+			if args[0] == "-include" {
+				if len(args) > 2 {
+					ctx.PropertyErrorf(prop, "`-include` only takes one argument: `%s`", flag)
+				}
+				path := filepath.Clean(args[1])
+				if strings.HasPrefix("/", path) {
+					ctx.PropertyErrorf(prop, "Path must not be an absolute path: %s", flag)
+				} else if strings.HasPrefix("../", path) {
+					ctx.PropertyErrorf(prop, "Path must not start with `../`: `%s`. Use include_dirs to -include from a different directory", flag)
+				}
+			} else {
+				ctx.PropertyErrorf(prop, "Bad flag: `%s` is not an allowed multi-word flag. Should it be split into multiple flags?", flag)
+			}
+		}
+	}
+}
+
+// Check for bad ldflags and suggest alternatives. Only use this for flags
+// explicitly passed by the user, since these flags may be used internally.
+func CheckBadLinkerFlags(ctx ModuleContext, prop string, flags []string) {
+	for _, flag := range flags {
+		flag = strings.TrimSpace(flag)
+
+		if !strings.HasPrefix(flag, "-") {
+			ctx.PropertyErrorf(prop, "Flag `%s` must start with `-`", flag)
+		} else if strings.HasPrefix(flag, "-l") {
+			if ctx.Host() {
+				ctx.PropertyErrorf(prop, "Bad flag: `%s`, use shared_libs or host_ldlibs instead", flag)
+			} else {
+				ctx.PropertyErrorf(prop, "Bad flag: `%s`, use shared_libs instead", flag)
+			}
+		} else if strings.HasPrefix(flag, "-L") {
+			ctx.PropertyErrorf(prop, "Bad flag: `%s` is not allowed", flag)
+		} else if strings.Contains(flag, " ") {
+			ctx.PropertyErrorf(prop, "Bad flag: `%s` is not an allowed multi-word flag. Should it be split into multiple flags?", flag)
+		}
+	}
+}
+
+// Check for bad host_ldlibs
+func CheckBadHostLdlibs(ctx ModuleContext, prop string, flags []string) {
+	allowed_ldlibs := ctx.toolchain().AvailableLibraries()
+
+	if !ctx.Host() {
+		panic("Invalid call to CheckBadHostLdlibs")
+	}
+
+	for _, flag := range flags {
+		flag = strings.TrimSpace(flag)
+
+		// TODO: Probably should just redo this property to prefix -l in Soong
+		if !strings.HasPrefix(flag, "-l") {
+			ctx.PropertyErrorf(prop, "Invalid flag: `%s`, must start with `-l`", flag)
+		} else if !inList(flag, allowed_ldlibs) {
+			ctx.PropertyErrorf(prop, "Host library `%s` not available", flag)
+		}
+	}
+}