diff --git a/ui/build/config.go b/ui/build/config.go
index 1dd948c..077a4d1 100644
--- a/ui/build/config.go
+++ b/ui/build/config.go
@@ -35,10 +35,10 @@
 )
 
 const (
-	envConfigDir  = "vendor/google/tools/soong_config"
-	jsonSuffix    = "json"
+	envConfigDir = "vendor/google/tools/soong_config"
+	jsonSuffix   = "json"
 
-	configFetcher = "vendor/google/tools/soong/expconfigfetcher"
+	configFetcher         = "vendor/google/tools/soong/expconfigfetcher"
 	envConfigFetchTimeout = 10 * time.Second
 )
 
@@ -62,6 +62,7 @@
 	jsonModuleGraph bool
 	bp2build        bool
 	queryview       bool
+	reportMkMetrics bool // Collect and report mk2bp migration progress metrics.
 	soongDocs       bool
 	skipConfig      bool
 	skipKati        bool
@@ -155,7 +156,7 @@
 	}
 
 	configExists := false
-	outConfigFilePath := filepath.Join(config.OutDir(), envConfigName + jsonSuffix)
+	outConfigFilePath := filepath.Join(config.OutDir(), envConfigName+jsonSuffix)
 	if _, err := os.Stat(outConfigFilePath); err == nil {
 		configExists = true
 	}
@@ -711,6 +712,8 @@
 			c.skipConfig = true
 		} else if arg == "--skip-soong-tests" {
 			c.skipSoongTests = true
+		} else if arg == "--mk-metrics" {
+			c.reportMkMetrics = true
 		} else if len(arg) > 0 && arg[0] == '-' {
 			parseArgNum := func(def int) int {
 				if len(arg) > 2 {
@@ -1381,6 +1384,11 @@
 	return filepath.Join(c.LogsDir(), "bazel_metrics")
 }
 
+// MkFileMetrics returns the file path for make-related metrics.
+func (c *configImpl) MkMetrics() string {
+	return filepath.Join(c.LogsDir(), "mk_metrics.pb")
+}
+
 func (c *configImpl) SetEmptyNinjaFile(v bool) {
 	c.emptyNinjaFile = v
 }
diff --git a/ui/build/finder.go b/ui/build/finder.go
index 68efe21..262de3d 100644
--- a/ui/build/finder.go
+++ b/ui/build/finder.go
@@ -138,6 +138,17 @@
 		ctx.Fatalf("Could not export module list: %v", err)
 	}
 
+	// Gate collecting/reporting mk metrics on builds that specifically request
+	// it, as identifying the total number of mk files adds 4-5ms onto null
+	// builds.
+	if config.reportMkMetrics {
+		androidMksTotal := f.FindNamedAt(".", "Android.mk")
+
+		ctx.Metrics.SetToplevelMakefiles(len(androidMks))
+		ctx.Metrics.SetTotalMakefiles(len(androidMksTotal))
+		ctx.Metrics.DumpMkMetrics(config.MkMetrics())
+	}
+
 	// Stop searching a subdirectory recursively after finding a CleanSpec.mk.
 	cleanSpecs := f.FindFirstNamedAt(".", "CleanSpec.mk")
 	err = dumpListToFile(ctx, config, cleanSpecs, filepath.Join(dumpDir, "CleanSpec.mk.list"))
diff --git a/ui/metrics/Android.bp b/ui/metrics/Android.bp
index 3ba3907..05db1d7 100644
--- a/ui/metrics/Android.bp
+++ b/ui/metrics/Android.bp
@@ -21,9 +21,10 @@
     pkgPath: "android/soong/ui/metrics",
     deps: [
         "golang-protobuf-proto",
+        "soong-ui-bp2build_metrics_proto",
         "soong-ui-metrics_upload_proto",
         "soong-ui-metrics_proto",
-        "soong-ui-bp2build_metrics_proto",
+        "soong-ui-mk_metrics_proto",
         "soong-ui-tracer",
         "soong-shared",
     ],
@@ -71,3 +72,15 @@
         "bp2build_metrics_proto/bp2build_metrics.pb.go",
     ],
 }
+
+bootstrap_go_package {
+    name: "soong-ui-mk_metrics_proto",
+    pkgPath: "android/soong/ui/metrics/mk_metrics_proto",
+    deps: [
+        "golang-protobuf-reflect-protoreflect",
+        "golang-protobuf-runtime-protoimpl",
+    ],
+    srcs: [
+        "mk_metrics_proto/mk_metrics.pb.go",
+    ],
+}
diff --git a/ui/metrics/metrics.go b/ui/metrics/metrics.go
index 80f8c1a..6f1ed60 100644
--- a/ui/metrics/metrics.go
+++ b/ui/metrics/metrics.go
@@ -41,6 +41,7 @@
 	"google.golang.org/protobuf/proto"
 
 	soong_metrics_proto "android/soong/ui/metrics/metrics_proto"
+	mk_metrics_proto "android/soong/ui/metrics/mk_metrics_proto"
 )
 
 const (
@@ -62,14 +63,22 @@
 	Total = "total"
 )
 
-// Metrics is a struct that stores collected metrics during the course
-// of a build which later is dumped to a MetricsBase protobuf file.
-// See ui/metrics/metrics_proto/metrics.proto for further details
-// on what information is collected.
+// Metrics is a struct that stores collected metrics during the course of a
+// build. It is later dumped to protobuf files. See underlying metrics protos
+// for further details on what information is collected.
 type Metrics struct {
-	// The protobuf message that is later written to the file.
+	// Protobuf containing various top-level build metrics. These include:
+	// 1. Build identifiers (ex: branch ID, requested product, hostname,
+	//    originating command)
+	// 2. Per-subprocess top-level metrics (ex: ninja process IO and runtime).
+	//    Note that, since these metrics are reported by soong_ui, there is little
+	//    insight that can be provided into performance breakdowns of individual
+	//    subprocesses.
 	metrics soong_metrics_proto.MetricsBase
 
+	// Protobuf containing metrics pertaining to number of makefiles in a build.
+	mkMetrics mk_metrics_proto.MkMetrics
+
 	// A list of pending build events.
 	EventTracer *EventTracer
 }
@@ -78,11 +87,24 @@
 func New() (metrics *Metrics) {
 	m := &Metrics{
 		metrics:     soong_metrics_proto.MetricsBase{},
+		mkMetrics:   mk_metrics_proto.MkMetrics{},
 		EventTracer: &EventTracer{},
 	}
 	return m
 }
 
+func (m *Metrics) SetTotalMakefiles(total int) {
+	m.mkMetrics.TotalMakefiles = uint32(total)
+}
+
+func (m *Metrics) SetToplevelMakefiles(total int) {
+	m.mkMetrics.ToplevelMakefiles = uint32(total)
+}
+
+func (m *Metrics) DumpMkMetrics(outPath string) {
+	shared.Save(&m.mkMetrics, outPath)
+}
+
 // SetTimeMetrics stores performance information from an executed block of
 // code.
 func (m *Metrics) SetTimeMetrics(perf soong_metrics_proto.PerfInfo) {
diff --git a/ui/metrics/mk_metrics_proto/mk_metrics.pb.go b/ui/metrics/mk_metrics_proto/mk_metrics.pb.go
new file mode 100644
index 0000000..32e136a
--- /dev/null
+++ b/ui/metrics/mk_metrics_proto/mk_metrics.pb.go
@@ -0,0 +1,177 @@
+// Copyright 2022 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.
+
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// versions:
+// 	protoc-gen-go v1.27.1
+// 	protoc        v3.9.1
+// source: mk_metrics.proto
+
+package mk_metrics_proto
+
+import (
+	protoreflect "google.golang.org/protobuf/reflect/protoreflect"
+	protoimpl "google.golang.org/protobuf/runtime/protoimpl"
+	reflect "reflect"
+	sync "sync"
+)
+
+const (
+	// Verify that this generated code is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(20 - protoimpl.MinVersion)
+	// Verify that runtime/protoimpl is sufficiently up-to-date.
+	_ = protoimpl.EnforceVersion(protoimpl.MaxVersion - 20)
+)
+
+// Contains metrics pertaining to makefiles.
+type MkMetrics struct {
+	state         protoimpl.MessageState
+	sizeCache     protoimpl.SizeCache
+	unknownFields protoimpl.UnknownFields
+
+	// Total number of mk files present in the workspace.
+	TotalMakefiles uint32 `protobuf:"varint,1,opt,name=totalMakefiles,proto3" json:"totalMakefiles,omitempty"`
+	// Number of top-level mk files present in the workspace.
+	// A mk file is "top level" if there are no mk files in its parent
+	// direrctories.
+	// This value is equivalent to the number of entries in Android.mk.list.
+	ToplevelMakefiles uint32 `protobuf:"varint,2,opt,name=toplevelMakefiles,proto3" json:"toplevelMakefiles,omitempty"`
+}
+
+func (x *MkMetrics) Reset() {
+	*x = MkMetrics{}
+	if protoimpl.UnsafeEnabled {
+		mi := &file_mk_metrics_proto_msgTypes[0]
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		ms.StoreMessageInfo(mi)
+	}
+}
+
+func (x *MkMetrics) String() string {
+	return protoimpl.X.MessageStringOf(x)
+}
+
+func (*MkMetrics) ProtoMessage() {}
+
+func (x *MkMetrics) ProtoReflect() protoreflect.Message {
+	mi := &file_mk_metrics_proto_msgTypes[0]
+	if protoimpl.UnsafeEnabled && x != nil {
+		ms := protoimpl.X.MessageStateOf(protoimpl.Pointer(x))
+		if ms.LoadMessageInfo() == nil {
+			ms.StoreMessageInfo(mi)
+		}
+		return ms
+	}
+	return mi.MessageOf(x)
+}
+
+// Deprecated: Use MkMetrics.ProtoReflect.Descriptor instead.
+func (*MkMetrics) Descriptor() ([]byte, []int) {
+	return file_mk_metrics_proto_rawDescGZIP(), []int{0}
+}
+
+func (x *MkMetrics) GetTotalMakefiles() uint32 {
+	if x != nil {
+		return x.TotalMakefiles
+	}
+	return 0
+}
+
+func (x *MkMetrics) GetToplevelMakefiles() uint32 {
+	if x != nil {
+		return x.ToplevelMakefiles
+	}
+	return 0
+}
+
+var File_mk_metrics_proto protoreflect.FileDescriptor
+
+var file_mk_metrics_proto_rawDesc = []byte{
+	0x0a, 0x10, 0x6d, 0x6b, 0x5f, 0x6d, 0x65, 0x74, 0x72, 0x69, 0x63, 0x73, 0x2e, 0x70, 0x72, 0x6f,
+	0x74, 0x6f, 0x12, 0x16, 0x73, 0x6f, 0x6f, 0x6e, 0x67, 0x5f, 0x62, 0x75, 0x69, 0x6c, 0x64, 0x5f,
+	0x6d, 0x6b, 0x5f, 0x6d, 0x65, 0x74, 0x72, 0x69, 0x63, 0x73, 0x22, 0x61, 0x0a, 0x09, 0x4d, 0x6b,
+	0x4d, 0x65, 0x74, 0x72, 0x69, 0x63, 0x73, 0x12, 0x26, 0x0a, 0x0e, 0x74, 0x6f, 0x74, 0x61, 0x6c,
+	0x4d, 0x61, 0x6b, 0x65, 0x66, 0x69, 0x6c, 0x65, 0x73, 0x18, 0x01, 0x20, 0x01, 0x28, 0x0d, 0x52,
+	0x0e, 0x74, 0x6f, 0x74, 0x61, 0x6c, 0x4d, 0x61, 0x6b, 0x65, 0x66, 0x69, 0x6c, 0x65, 0x73, 0x12,
+	0x2c, 0x0a, 0x11, 0x74, 0x6f, 0x70, 0x6c, 0x65, 0x76, 0x65, 0x6c, 0x4d, 0x61, 0x6b, 0x65, 0x66,
+	0x69, 0x6c, 0x65, 0x73, 0x18, 0x02, 0x20, 0x01, 0x28, 0x0d, 0x52, 0x11, 0x74, 0x6f, 0x70, 0x6c,
+	0x65, 0x76, 0x65, 0x6c, 0x4d, 0x61, 0x6b, 0x65, 0x66, 0x69, 0x6c, 0x65, 0x73, 0x42, 0x2b, 0x5a,
+	0x29, 0x61, 0x6e, 0x64, 0x72, 0x6f, 0x69, 0x64, 0x2f, 0x73, 0x6f, 0x6f, 0x6e, 0x67, 0x2f, 0x75,
+	0x69, 0x2f, 0x6d, 0x65, 0x74, 0x72, 0x69, 0x63, 0x73, 0x2f, 0x6d, 0x6b, 0x5f, 0x6d, 0x65, 0x74,
+	0x72, 0x69, 0x63, 0x73, 0x5f, 0x70, 0x72, 0x6f, 0x74, 0x6f, 0x62, 0x06, 0x70, 0x72, 0x6f, 0x74,
+	0x6f, 0x33,
+}
+
+var (
+	file_mk_metrics_proto_rawDescOnce sync.Once
+	file_mk_metrics_proto_rawDescData = file_mk_metrics_proto_rawDesc
+)
+
+func file_mk_metrics_proto_rawDescGZIP() []byte {
+	file_mk_metrics_proto_rawDescOnce.Do(func() {
+		file_mk_metrics_proto_rawDescData = protoimpl.X.CompressGZIP(file_mk_metrics_proto_rawDescData)
+	})
+	return file_mk_metrics_proto_rawDescData
+}
+
+var file_mk_metrics_proto_msgTypes = make([]protoimpl.MessageInfo, 1)
+var file_mk_metrics_proto_goTypes = []interface{}{
+	(*MkMetrics)(nil), // 0: soong_build_mk_metrics.MkMetrics
+}
+var file_mk_metrics_proto_depIdxs = []int32{
+	0, // [0:0] is the sub-list for method output_type
+	0, // [0:0] is the sub-list for method input_type
+	0, // [0:0] is the sub-list for extension type_name
+	0, // [0:0] is the sub-list for extension extendee
+	0, // [0:0] is the sub-list for field type_name
+}
+
+func init() { file_mk_metrics_proto_init() }
+func file_mk_metrics_proto_init() {
+	if File_mk_metrics_proto != nil {
+		return
+	}
+	if !protoimpl.UnsafeEnabled {
+		file_mk_metrics_proto_msgTypes[0].Exporter = func(v interface{}, i int) interface{} {
+			switch v := v.(*MkMetrics); i {
+			case 0:
+				return &v.state
+			case 1:
+				return &v.sizeCache
+			case 2:
+				return &v.unknownFields
+			default:
+				return nil
+			}
+		}
+	}
+	type x struct{}
+	out := protoimpl.TypeBuilder{
+		File: protoimpl.DescBuilder{
+			GoPackagePath: reflect.TypeOf(x{}).PkgPath(),
+			RawDescriptor: file_mk_metrics_proto_rawDesc,
+			NumEnums:      0,
+			NumMessages:   1,
+			NumExtensions: 0,
+			NumServices:   0,
+		},
+		GoTypes:           file_mk_metrics_proto_goTypes,
+		DependencyIndexes: file_mk_metrics_proto_depIdxs,
+		MessageInfos:      file_mk_metrics_proto_msgTypes,
+	}.Build()
+	File_mk_metrics_proto = out.File
+	file_mk_metrics_proto_rawDesc = nil
+	file_mk_metrics_proto_goTypes = nil
+	file_mk_metrics_proto_depIdxs = nil
+}
diff --git a/ui/metrics/mk_metrics_proto/mk_metrics.proto b/ui/metrics/mk_metrics_proto/mk_metrics.proto
new file mode 100644
index 0000000..df7bca3
--- /dev/null
+++ b/ui/metrics/mk_metrics_proto/mk_metrics.proto
@@ -0,0 +1,30 @@
+// Copyright 2022 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.
+
+syntax = "proto3";
+
+package soong_build_mk_metrics;
+option go_package = "android/soong/ui/metrics/mk_metrics_proto";
+
+// Contains metrics pertaining to makefiles.
+message MkMetrics {
+  // Total number of mk files present in the workspace.
+  uint32 totalMakefiles = 1;
+
+  // Number of top-level mk files present in the workspace.
+  // A mk file is "top level" if there are no mk files in its parent
+  // direrctories.
+  // This value is equivalent to the number of entries in Android.mk.list.
+  uint32 toplevelMakefiles = 2;
+}
diff --git a/ui/metrics/mk_metrics_proto/regen.sh b/ui/metrics/mk_metrics_proto/regen.sh
new file mode 100755
index 0000000..64018d4
--- /dev/null
+++ b/ui/metrics/mk_metrics_proto/regen.sh
@@ -0,0 +1,29 @@
+#!/bin/bash -e
+
+# Copyright 2022 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.
+
+# Generates the golang source file of the mk_metrics.proto protobuf file.
+
+function die() { echo "ERROR: $1" >&2; exit 1; }
+
+readonly error_msg="Maybe you need to run 'lunch aosp_arm-eng && m aprotoc blueprint_tools'?"
+
+if ! hash aprotoc &>/dev/null; then
+  die "could not find aprotoc. ${error_msg}"
+fi
+
+if ! aprotoc --go_out=paths=source_relative:. mk_metrics.proto; then
+  die "build failed. ${error_msg}"
+fi