diff --git a/Android.bp b/Android.bp
index afbae172a..1dfac875a 100644
--- a/Android.bp
+++ b/Android.bp
@@ -172,6 +172,7 @@ bootstrap_go_package {
         "cc/vndk_prebuilt.go",
         "cc/xom.go",
 
+        "cc/cflag_artifacts.go",
         "cc/cmakelists.go",
         "cc/compdb.go",
         "cc/compiler.go",
@@ -304,7 +305,6 @@ bootstrap_go_package {
         "java/jdeps_test.go",
         "java/kotlin_test.go",
         "java/plugin_test.go",
-        "java/robolectric_test.go",
         "java/sdk_test.go",
     ],
     pluginFor: ["soong_build"],
diff --git a/android/util.go b/android/util.go
index 010244209..71ded5e07 100644
--- a/android/util.go
+++ b/android/util.go
@@ -319,3 +319,36 @@ func SplitFileExt(name string) (string, string, string) {
 
 	return root, suffix, ext
 }
+
+// ShardPaths takes a Paths, and returns a slice of Paths where each one has at most shardSize paths.
+func ShardPaths(paths Paths, shardSize int) []Paths {
+	if len(paths) == 0 {
+		return nil
+	}
+	ret := make([]Paths, 0, (len(paths)+shardSize-1)/shardSize)
+	for len(paths) > shardSize {
+		ret = append(ret, paths[0:shardSize])
+		paths = paths[shardSize:]
+	}
+	if len(paths) > 0 {
+		ret = append(ret, paths)
+	}
+	return ret
+}
+
+// ShardStrings takes a slice of strings, and returns a slice of slices of strings where each one has at most shardSize
+// elements.
+func ShardStrings(s []string, shardSize int) [][]string {
+	if len(s) == 0 {
+		return nil
+	}
+	ret := make([][]string, 0, (len(s)+shardSize-1)/shardSize)
+	for len(s) > shardSize {
+		ret = append(ret, s[0:shardSize])
+		s = s[shardSize:]
+	}
+	if len(s) > 0 {
+		ret = append(ret, s)
+	}
+	return ret
+}
diff --git a/android/util_test.go b/android/util_test.go
index 1df1c5af5..90fefeede 100644
--- a/android/util_test.go
+++ b/android/util_test.go
@@ -469,3 +469,102 @@ func TestSplitFileExt(t *testing.T) {
 		}
 	})
 }
+
+func Test_Shard(t *testing.T) {
+	type args struct {
+		strings   []string
+		shardSize int
+	}
+	tests := []struct {
+		name string
+		args args
+		want [][]string
+	}{
+		{
+			name: "empty",
+			args: args{
+				strings:   nil,
+				shardSize: 1,
+			},
+			want: [][]string(nil),
+		},
+		{
+			name: "single shard",
+			args: args{
+				strings:   []string{"a", "b"},
+				shardSize: 2,
+			},
+			want: [][]string{{"a", "b"}},
+		},
+		{
+			name: "single short shard",
+			args: args{
+				strings:   []string{"a", "b"},
+				shardSize: 3,
+			},
+			want: [][]string{{"a", "b"}},
+		},
+		{
+			name: "shard per input",
+			args: args{
+				strings:   []string{"a", "b", "c"},
+				shardSize: 1,
+			},
+			want: [][]string{{"a"}, {"b"}, {"c"}},
+		},
+		{
+			name: "balanced shards",
+			args: args{
+				strings:   []string{"a", "b", "c", "d"},
+				shardSize: 2,
+			},
+			want: [][]string{{"a", "b"}, {"c", "d"}},
+		},
+		{
+			name: "unbalanced shards",
+			args: args{
+				strings:   []string{"a", "b", "c"},
+				shardSize: 2,
+			},
+			want: [][]string{{"a", "b"}, {"c"}},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Run("strings", func(t *testing.T) {
+				if got := ShardStrings(tt.args.strings, tt.args.shardSize); !reflect.DeepEqual(got, tt.want) {
+					t.Errorf("ShardStrings(%v, %v) = %v, want %v",
+						tt.args.strings, tt.args.shardSize, got, tt.want)
+				}
+			})
+
+			t.Run("paths", func(t *testing.T) {
+				stringsToPaths := func(strings []string) Paths {
+					if strings == nil {
+						return nil
+					}
+					paths := make(Paths, len(strings))
+					for i, s := range strings {
+						paths[i] = PathForTesting(s)
+					}
+					return paths
+				}
+
+				paths := stringsToPaths(tt.args.strings)
+
+				var want []Paths
+				if sWant := tt.want; sWant != nil {
+					want = make([]Paths, len(sWant))
+					for i, w := range sWant {
+						want[i] = stringsToPaths(w)
+					}
+				}
+
+				if got := ShardPaths(paths, tt.args.shardSize); !reflect.DeepEqual(got, want) {
+					t.Errorf("ShardPaths(%v, %v) = %v, want %v",
+						paths, tt.args.shardSize, got, want)
+				}
+			})
+		})
+	}
+}
diff --git a/cc/cflag_artifacts.go b/cc/cflag_artifacts.go
new file mode 100644
index 000000000..9ed3876ab
--- /dev/null
+++ b/cc/cflag_artifacts.go
@@ -0,0 +1,188 @@
+package cc
+
+import (
+	"fmt"
+	"sort"
+	"strings"
+
+	"github.com/google/blueprint/proptools"
+
+	"android/soong/android"
+)
+
+func init() {
+	android.RegisterSingletonType("cflag_artifacts_text", cflagArtifactsTextFactory)
+}
+
+var (
+	TrackedCFlags = []string{
+		"-Wall",
+		"-Werror",
+		"-Wextra",
+		"-Wthread-safety",
+		"-O3",
+	}
+
+	TrackedCFlagsDir = []string{
+		"device/google/",
+		"vendor/google/",
+	}
+)
+
+const FileBP = 50
+
+// Stores output files.
+type cflagArtifactsText struct {
+	interOutputs map[string]android.WritablePaths
+	outputs      android.WritablePaths
+}
+
+// allowedDir verifies if the directory/project is part of the TrackedCFlagsDir
+// filter.
+func allowedDir(subdir string) bool {
+	subdir += "/"
+	for _, prefix := range TrackedCFlagsDir {
+		if strings.HasPrefix(subdir, prefix) {
+			return true
+		}
+	}
+	return false
+}
+
+func (s *cflagArtifactsText) genFlagFilename(flag string) string {
+	return fmt.Sprintf("module_cflags%s.txt", flag)
+}
+
+// incrementFile is used to generate an output path object with the passed in flag
+// and part number.
+// e.g. FLAG + part # -> out/soong/cflags/module_cflags-FLAG.txt.0
+func (s *cflagArtifactsText) incrementFile(ctx android.SingletonContext,
+	flag string, part int) (string, android.OutputPath) {
+
+	filename := fmt.Sprintf("%s.%d", s.genFlagFilename(flag), part)
+	filepath := android.PathForOutput(ctx, "cflags", filename)
+	s.interOutputs[flag] = append(s.interOutputs[flag], filepath)
+	return filename, filepath
+}
+
+// GenCFlagArtifactParts is used to generate the build rules which produce the
+// intermediary files for each desired C Flag artifact
+// e.g. module_cflags-FLAG.txt.0, module_cflags-FLAG.txt.1, ...
+func (s *cflagArtifactsText) GenCFlagArtifactParts(ctx android.SingletonContext,
+	flag string, using bool, modules []string, part int) int {
+
+	cleanedName := strings.Replace(flag, "=", "_", -1)
+	filename, filepath := s.incrementFile(ctx, cleanedName, part)
+	rule := android.NewRuleBuilder()
+	rule.Command().Textf("rm -f %s", filepath.String())
+
+	if using {
+		rule.Command().
+			Textf("echo '# Modules using %s'", flag).
+			FlagWithOutput(">> ", filepath)
+	} else {
+		rule.Command().
+			Textf("echo '# Modules not using %s'", flag).
+			FlagWithOutput(">> ", filepath)
+	}
+
+	length := len(modules)
+
+	if length == 0 {
+		rule.Build(pctx, ctx, filename, "gen "+filename)
+		part++
+	}
+
+	// Following loop splits the module list for each tracked C Flag into
+	// chunks of length FileBP (file breakpoint) and generates a partial artifact
+	// (intermediary file) build rule for each split.
+	moduleShards := android.ShardStrings(modules, FileBP)
+	for index, shard := range moduleShards {
+		rule.Command().
+			Textf("for m in %s; do echo $m",
+				strings.Join(proptools.ShellEscapeList(shard), " ")).
+			FlagWithOutput(">> ", filepath).
+			Text("; done")
+		rule.Build(pctx, ctx, filename, "gen "+filename)
+
+		if index+1 != len(moduleShards) {
+			filename, filepath = s.incrementFile(ctx, cleanedName, part+index+1)
+			rule = android.NewRuleBuilder()
+			rule.Command().Textf("rm -f %s", filepath.String())
+		}
+	}
+
+	return part + len(moduleShards)
+}
+
+// GenCFlagArtifacts is used to generate build rules which combine the
+// intermediary files of a specific tracked flag into a single C Flag artifact
+// for each tracked flag.
+// e.g. module_cflags-FLAG.txt.0 + module_cflags-FLAG.txt.1 = module_cflags-FLAG.txt
+func (s *cflagArtifactsText) GenCFlagArtifacts(ctx android.SingletonContext) {
+	// Scans through s.interOutputs and creates a build rule for each tracked C
+	// Flag that concatenates the associated intermediary file into a single
+	// artifact.
+	for _, flag := range TrackedCFlags {
+		// Generate build rule to combine related intermediary files into a
+		// C Flag artifact
+		rule := android.NewRuleBuilder()
+		filename := s.genFlagFilename(flag)
+		outputpath := android.PathForOutput(ctx, "cflags", filename)
+		rule.Command().
+			Text("cat").
+			Inputs(s.interOutputs[flag].Paths()).
+			FlagWithOutput("> ", outputpath)
+		rule.Build(pctx, ctx, filename, "gen "+filename)
+		s.outputs = append(s.outputs, outputpath)
+	}
+}
+
+func (s *cflagArtifactsText) GenerateBuildActions(ctx android.SingletonContext) {
+	modulesWithCFlag := make(map[string][]string)
+
+	// Scan through all modules, selecting the ones that are part of the filter,
+	// and then storing into a map which tracks whether or not tracked C flag is
+	// used or not.
+	ctx.VisitAllModules(func(module android.Module) {
+		if ccModule, ok := module.(*Module); ok {
+			if allowedDir(ctx.ModuleDir(ccModule)) {
+				cflags := ccModule.flags.CFlags
+				cppflags := ccModule.flags.CppFlags
+				module := fmt.Sprintf("%s:%s (%s)",
+					ctx.BlueprintFile(ccModule),
+					ctx.ModuleName(ccModule),
+					ctx.ModuleSubDir(ccModule))
+				for _, flag := range TrackedCFlags {
+					if inList(flag, cflags) || inList(flag, cppflags) {
+						modulesWithCFlag[flag] = append(modulesWithCFlag[flag], module)
+					} else {
+						modulesWithCFlag["!"+flag] = append(modulesWithCFlag["!"+flag], module)
+					}
+				}
+			}
+		}
+	})
+
+	// Traversing map and setting up rules to produce intermediary files which
+	// contain parts of each expected C Flag artifact.
+	for _, flag := range TrackedCFlags {
+		sort.Strings(modulesWithCFlag[flag])
+		part := s.GenCFlagArtifactParts(ctx, flag, true, modulesWithCFlag[flag], 0)
+		sort.Strings(modulesWithCFlag["!"+flag])
+		s.GenCFlagArtifactParts(ctx, flag, false, modulesWithCFlag["!"+flag], part)
+	}
+
+	// Combine intermediary files into a single C Flag artifact.
+	s.GenCFlagArtifacts(ctx)
+}
+
+func cflagArtifactsTextFactory() android.Singleton {
+	return &cflagArtifactsText{
+		interOutputs: make(map[string]android.WritablePaths),
+	}
+}
+
+func (s *cflagArtifactsText) MakeVars(ctx android.MakeVarsContext) {
+	ctx.Strict("SOONG_MODULES_CFLAG_ARTIFACTS", strings.Join(s.outputs.Strings(), " "))
+}
diff --git a/java/aapt2.go b/java/aapt2.go
index f0eb99cee..cfe0deab1 100644
--- a/java/aapt2.go
+++ b/java/aapt2.go
@@ -63,7 +63,7 @@ var aapt2CompileRule = pctx.AndroidStaticRule("aapt2Compile",
 func aapt2Compile(ctx android.ModuleContext, dir android.Path, paths android.Paths,
 	flags []string) android.WritablePaths {
 
-	shards := shardPaths(paths, AAPT2_SHARD_SIZE)
+	shards := android.ShardPaths(paths, AAPT2_SHARD_SIZE)
 
 	ret := make(android.WritablePaths, 0, len(paths))
 
diff --git a/java/java.go b/java/java.go
index ce72c2760..f7b0f53ba 100644
--- a/java/java.go
+++ b/java/java.go
@@ -580,18 +580,6 @@ func hasSrcExt(srcs []string, ext string) bool {
 	return false
 }
 
-func shardPaths(paths android.Paths, shardSize int) []android.Paths {
-	ret := make([]android.Paths, 0, (len(paths)+shardSize-1)/shardSize)
-	for len(paths) > shardSize {
-		ret = append(ret, paths[0:shardSize])
-		paths = paths[shardSize:]
-	}
-	if len(paths) > 0 {
-		ret = append(ret, paths)
-	}
-	return ret
-}
-
 func (j *Module) hasSrcExt(ext string) bool {
 	return hasSrcExt(j.properties.Srcs, ext)
 }
@@ -1156,7 +1144,7 @@ func (j *Module) compile(ctx android.ModuleContext, aaptSrcJar android.Path) {
 			shardSize := int(*(j.properties.Javac_shard_size))
 			var shardSrcs []android.Paths
 			if len(uniqueSrcFiles) > 0 {
-				shardSrcs = shardPaths(uniqueSrcFiles, shardSize)
+				shardSrcs = android.ShardPaths(uniqueSrcFiles, shardSize)
 				for idx, shardSrc := range shardSrcs {
 					classes := j.compileJavaClasses(ctx, jarName, idx, shardSrc,
 						nil, flags, extraJarDeps)
diff --git a/java/robolectric.go b/java/robolectric.go
index dbf54c9b3..b7646eb45 100644
--- a/java/robolectric.go
+++ b/java/robolectric.go
@@ -123,25 +123,6 @@ func (r *robolectricTest) GenerateAndroidBuildActions(ctx android.ModuleContext)
 	}
 }
 
-func shardTests(paths []string, shards int) [][]string {
-	if shards > len(paths) {
-		shards = len(paths)
-	}
-	if shards == 0 {
-		return nil
-	}
-	ret := make([][]string, 0, shards)
-	shardSize := (len(paths) + shards - 1) / shards
-	for len(paths) > shardSize {
-		ret = append(ret, paths[0:shardSize])
-		paths = paths[shardSize:]
-	}
-	if len(paths) > 0 {
-		ret = append(ret, paths)
-	}
-	return ret
-}
-
 func generateRoboTestConfig(ctx android.ModuleContext, outputFile android.WritablePath, instrumentedApp *AndroidApp) {
 	manifest := instrumentedApp.mergedManifestFile
 	resourceApk := instrumentedApp.outputFile
@@ -183,7 +164,9 @@ func (r *robolectricTest) AndroidMkEntries() android.AndroidMkEntries {
 	entries.ExtraFooters = []android.AndroidMkExtraFootersFunc{
 		func(w io.Writer, name, prefix, moduleDir string, entries *android.AndroidMkEntries) {
 			if s := r.robolectricProperties.Test_options.Shards; s != nil && *s > 1 {
-				shards := shardTests(r.tests, int(*s))
+				numShards := int(*s)
+				shardSize := (len(r.tests) + numShards - 1) / numShards
+				shards := android.ShardStrings(r.tests, shardSize)
 				for i, shard := range shards {
 					r.writeTestRunner(w, name, "Run"+name+strconv.Itoa(i), shard)
 				}
diff --git a/java/robolectric_test.go b/java/robolectric_test.go
deleted file mode 100644
index e89c6e74c..000000000
--- a/java/robolectric_test.go
+++ /dev/null
@@ -1,88 +0,0 @@
-// 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 java
-
-import (
-	"reflect"
-	"testing"
-)
-
-func Test_shardTests(t *testing.T) {
-	type args struct {
-		paths  []string
-		shards int
-	}
-	tests := []struct {
-		name string
-		args args
-		want [][]string
-	}{
-		{
-			name: "empty",
-			args: args{
-				paths:  nil,
-				shards: 1,
-			},
-			want: [][]string(nil),
-		},
-		{
-			name: "too many shards",
-			args: args{
-				paths:  []string{"a", "b"},
-				shards: 3,
-			},
-			want: [][]string{{"a"}, {"b"}},
-		},
-		{
-			name: "single shard",
-			args: args{
-				paths:  []string{"a", "b"},
-				shards: 1,
-			},
-			want: [][]string{{"a", "b"}},
-		},
-		{
-			name: "shard per input",
-			args: args{
-				paths:  []string{"a", "b", "c"},
-				shards: 3,
-			},
-			want: [][]string{{"a"}, {"b"}, {"c"}},
-		},
-		{
-			name: "balanced shards",
-			args: args{
-				paths:  []string{"a", "b", "c", "d"},
-				shards: 2,
-			},
-			want: [][]string{{"a", "b"}, {"c", "d"}},
-		},
-		{
-			name: "unbalanced shards",
-			args: args{
-				paths:  []string{"a", "b", "c"},
-				shards: 2,
-			},
-			want: [][]string{{"a", "b"}, {"c"}},
-		},
-	}
-	for _, tt := range tests {
-		t.Run(tt.name, func(t *testing.T) {
-			if got := shardTests(tt.args.paths, tt.args.shards); !reflect.DeepEqual(got, tt.want) {
-				t.Errorf("shardTests() = %v, want %v", got, tt.want)
-			}
-		})
-	}
-}