diff --git a/ui/build/kati.go b/ui/build/kati.go
index 4bb2db9..cc02c76 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -59,11 +59,13 @@
 }
 
 func runKati(ctx Context, config Config) {
+	genKatiSuffix(ctx, config)
+
+	runKatiCleanSpec(ctx, config)
+
 	ctx.BeginTrace("kati")
 	defer ctx.EndTrace()
 
-	genKatiSuffix(ctx, config)
-
 	executable := config.PrebuiltBuildTool("ckati")
 	args := []string{
 		"--ninja",
@@ -159,3 +161,33 @@
 		fmt.Fprintln(ctx.Stdout())
 	}
 }
+
+func runKatiCleanSpec(ctx Context, config Config) {
+	ctx.BeginTrace("kati cleanspec")
+	defer ctx.EndTrace()
+
+	executable := config.PrebuiltBuildTool("ckati")
+	args := []string{
+		"--ninja",
+		"--ninja_dir=" + config.OutDir(),
+		"--ninja_suffix=" + config.KatiSuffix() + "-cleanspec",
+		"--regen",
+		"--detect_android_echo",
+		"--color_warnings",
+		"--gen_all_targets",
+		"--werror_find_emulator",
+		"--use_find_emulator",
+		"-f", "build/make/core/cleanbuild.mk",
+		"BUILDING_WITH_NINJA=true",
+		"SOONG_MAKEVARS_MK=" + config.SoongMakeVarsMk(),
+	}
+
+	cmd := Command(ctx, config, "ckati", executable, args...)
+	cmd.Sandbox = katiCleanSpecSandbox
+	cmd.Stdout = ctx.Stdout()
+	cmd.Stderr = ctx.Stderr()
+
+	// Kati leaks memory, so ensure leak detection is turned off
+	cmd.Environment.Set("ASAN_OPTIONS", "detect_leaks=0")
+	cmd.RunOrFatal()
+}