diff --git a/bp2build/metrics.go b/bp2build/metrics.go
index b3d5afb..68ac544 100644
--- a/bp2build/metrics.go
+++ b/bp2build/metrics.go
@@ -2,34 +2,52 @@
 
 import (
 	"fmt"
+	"os"
+	"path/filepath"
 	"strings"
 
 	"android/soong/android"
+	"android/soong/shared"
+	"android/soong/ui/metrics/bp2build_metrics_proto"
 )
 
 // Simple metrics struct to collect information about a Blueprint to BUILD
 // conversion process.
 type CodegenMetrics struct {
 	// Total number of Soong modules converted to generated targets
-	generatedModuleCount int
+	generatedModuleCount uint64
 
 	// Total number of Soong modules converted to handcrafted targets
-	handCraftedModuleCount int
+	handCraftedModuleCount uint64
 
 	// Total number of unconverted Soong modules
-	unconvertedModuleCount int
+	unconvertedModuleCount uint64
 
 	// Counts of generated Bazel targets per Bazel rule class
-	ruleClassCount map[string]int
+	ruleClassCount map[string]uint64
 
+	// List of modules with unconverted deps
+	// NOTE: NOT in the .proto
 	moduleWithUnconvertedDepsMsgs []string
 
+	// List of converted modules
 	convertedModules []string
 }
 
+// Serialize returns the protoized version of CodegenMetrics: bp2build_metrics_proto.Bp2BuildMetrics
+func (metrics *CodegenMetrics) Serialize() bp2build_metrics_proto.Bp2BuildMetrics {
+	return bp2build_metrics_proto.Bp2BuildMetrics{
+		GeneratedModuleCount:   metrics.generatedModuleCount,
+		HandCraftedModuleCount: metrics.handCraftedModuleCount,
+		UnconvertedModuleCount: metrics.unconvertedModuleCount,
+		RuleClassCount:         metrics.ruleClassCount,
+		ConvertedModules:       metrics.convertedModules,
+	}
+}
+
 // Print the codegen metrics to stdout.
 func (metrics *CodegenMetrics) Print() {
-	generatedTargetCount := 0
+	generatedTargetCount := uint64(0)
 	for _, ruleClass := range android.SortedStringKeys(metrics.ruleClassCount) {
 		count := metrics.ruleClassCount[ruleClass]
 		fmt.Printf("[bp2build] %s: %d targets\n", ruleClass, count)
@@ -45,6 +63,40 @@
 		strings.Join(metrics.moduleWithUnconvertedDepsMsgs, "\n\t"))
 }
 
+const bp2buildMetricsFilename = "bp2build_metrics.pb"
+
+// fail prints $PWD to stderr, followed by the given printf string and args (vals),
+// then the given alert, and then exits with 1 for failure
+func fail(err error, alertFmt string, vals ...interface{}) {
+	cwd, wderr := os.Getwd()
+	if wderr != nil {
+		cwd = "FAILED TO GET $PWD: " + wderr.Error()
+	}
+	fmt.Fprintf(os.Stderr, "\nIn "+cwd+":\n"+alertFmt+"\n"+err.Error()+"\n", vals...)
+	os.Exit(1)
+}
+
+// Write the bp2build-protoized codegen metrics into the given directory
+func (metrics *CodegenMetrics) Write(dir string) {
+	if _, err := os.Stat(dir); os.IsNotExist(err) {
+		// The metrics dir doesn't already exist, so create it (and parents)
+		if err := os.MkdirAll(dir, 0755); err != nil { // rx for all; w for user
+			fail(err, "Failed to `mkdir -p` %s", dir)
+		}
+	} else if err != nil {
+		fail(err, "Failed to `stat` %s", dir)
+	}
+	metricsFile := filepath.Join(dir, bp2buildMetricsFilename)
+	if err := metrics.dump(metricsFile); err != nil {
+		fail(err, "Error outputting %s", metricsFile)
+	}
+	if _, err := os.Stat(metricsFile); err != nil {
+		fail(err, "MISSING BP2BUILD METRICS OUTPUT: Failed to `stat` %s", metricsFile)
+	} else {
+		fmt.Printf("\nWrote bp2build metrics to: %s\n", metricsFile)
+	}
+}
+
 func (metrics *CodegenMetrics) IncrementRuleClassCount(ruleClass string) {
 	metrics.ruleClassCount[ruleClass] += 1
 }
@@ -53,12 +105,18 @@
 	metrics.unconvertedModuleCount += 1
 }
 
-func (metrics *CodegenMetrics) TotalModuleCount() int {
+func (metrics *CodegenMetrics) TotalModuleCount() uint64 {
 	return metrics.handCraftedModuleCount +
 		metrics.generatedModuleCount +
 		metrics.unconvertedModuleCount
 }
 
+// Dump serializes the metrics to the given filename
+func (metrics *CodegenMetrics) dump(filename string) (err error) {
+	ser := metrics.Serialize()
+	return shared.Save(&ser, filename)
+}
+
 type ConversionType int
 
 const (