diff --git a/cc/config/bp2build.go b/cc/config/bp2build.go
new file mode 100644
index 0000000..16892e6
--- /dev/null
+++ b/cc/config/bp2build.go
@@ -0,0 +1,148 @@
+// Copyright 2021 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 config
+
+import (
+	"android/soong/android"
+	"fmt"
+	"regexp"
+	"strings"
+)
+
+// Helpers for exporting cc configuration information to Bazel.
+
+var (
+	// Map containing toolchain variables that are independent of the
+	// environment variables of the build.
+	exportedVars = exportedVariablesMap{}
+)
+
+// variableValue is a string slice because the exported variables are all lists
+// of string, and it's simpler to manipulate string lists before joining them
+// into their final string representation.
+type variableValue []string
+
+// envDependentVariable is a toolchain variable computed based on an environment variable.
+type exportedVariablesMap map[string]variableValue
+
+func (m exportedVariablesMap) Set(k string, v variableValue) {
+	m[k] = v
+}
+
+// Convenience function to declare a static variable and export it to Bazel's cc_toolchain.
+func staticVariableExportedToBazel(name string, value []string) {
+	pctx.StaticVariable(name, strings.Join(value, " "))
+	exportedVars.Set(name, variableValue(value))
+}
+
+// BazelCcToolchainVars generates bzl file content containing variables for
+// Bazel's cc_toolchain configuration.
+func BazelCcToolchainVars() string {
+	ret := "# GENERATED FOR BAZEL FROM SOONG. DO NOT EDIT.\n\n"
+
+	// Ensure that string s has no invalid characters to be generated into the bzl file.
+	validateCharacters := func(s string) string {
+		for _, c := range []string{`\n`, `"`, `\`} {
+			if strings.Contains(s, c) {
+				panic(fmt.Errorf("%s contains illegal character %s", s, c))
+			}
+		}
+		return s
+	}
+
+	// For each exported variable, recursively expand elements in the variableValue
+	// list to ensure that interpolated variables are expanded according to their values
+	// in the exportedVars scope.
+	for _, k := range android.SortedStringKeys(exportedVars) {
+		variableValue := exportedVars[k]
+		var expandedVars []string
+		for _, v := range variableValue {
+			expandedVars = append(expandedVars, expandVar(v, exportedVars)...)
+		}
+		// Build the list for this variable.
+		list := "["
+		for _, flag := range expandedVars {
+			list += fmt.Sprintf("\n    \"%s\",", validateCharacters(flag))
+		}
+		list += "\n]"
+		// Assign the list as a bzl-private variable; this variable will be exported
+		// out through a constants struct later.
+		ret += fmt.Sprintf("_%s = %s\n", k, list)
+		ret += "\n"
+	}
+
+	// Build the exported constants struct.
+	ret += "constants = struct(\n"
+	for _, k := range android.SortedStringKeys(exportedVars) {
+		ret += fmt.Sprintf("    %s = _%s,\n", k, k)
+	}
+	ret += ")"
+	return ret
+}
+
+// expandVar recursively expand interpolated variables in the exportedVars scope.
+//
+// We're using a string slice to track the seen variables to avoid
+// stackoverflow errors with infinite recursion. it's simpler to use a
+// string slice than to handle a pass-by-referenced map, which would make it
+// quite complex to track depth-first interpolations. It's also unlikely the
+// interpolation stacks are deep (n > 1).
+func expandVar(toExpand string, exportedVars map[string]variableValue) []string {
+	// e.g. "${ClangExternalCflags}"
+	r := regexp.MustCompile(`\${([a-zA-Z0-9_]+)}`)
+
+	// Internal recursive function.
+	var expandVarInternal func(string, map[string]bool) []string
+	expandVarInternal = func(toExpand string, seenVars map[string]bool) []string {
+		var ret []string
+		for _, v := range strings.Split(toExpand, " ") {
+			matches := r.FindStringSubmatch(v)
+			if len(matches) == 0 {
+				return []string{v}
+			}
+
+			if len(matches) != 2 {
+				panic(fmt.Errorf(
+					"Expected to only match 1 subexpression in %s, got %d",
+					v,
+					len(matches)-1))
+			}
+
+			// Index 1 of FindStringSubmatch contains the subexpression match
+			// (variable name) of the capture group.
+			variable := matches[1]
+			// toExpand contains a variable.
+			if _, ok := seenVars[variable]; ok {
+				panic(fmt.Errorf(
+					"Unbounded recursive interpolation of variable: %s", variable))
+			}
+			// A map is passed-by-reference. Create a new map for
+			// this scope to prevent variables seen in one depth-first expansion
+			// to be also treated as "seen" in other depth-first traversals.
+			newSeenVars := map[string]bool{}
+			for k := range seenVars {
+				newSeenVars[k] = true
+			}
+			newSeenVars[variable] = true
+			unexpandedVars := exportedVars[variable]
+			for _, unexpandedVar := range unexpandedVars {
+				ret = append(ret, expandVarInternal(unexpandedVar, newSeenVars)...)
+			}
+		}
+		return ret
+	}
+
+	return expandVarInternal(toExpand, map[string]bool{})
+}