diff --git a/Android.bp b/Android.bp
index fe776df..97233f5 100644
--- a/Android.bp
+++ b/Android.bp
@@ -132,6 +132,7 @@
     pkgPath: "android/soong/cc/config",
     deps: [
         "soong-android",
+        "soong-remoteexec",
     ],
     srcs: [
         "cc/config/clang.go",
@@ -547,6 +548,22 @@
     pluginFor: ["soong_build"],
 }
 
+bootstrap_go_package {
+    name: "soong-remoteexec",
+    pkgPath: "android/soong/remoteexec",
+    deps: [
+        "blueprint",
+        "soong-android",
+    ],
+    srcs: [
+        "remoteexec/remoteexec.go",
+    ],
+    testSrcs: [
+        "remoteexec/remoteexec_test.go",
+    ],
+    pluginFor: ["soong_build"],
+}
+
 //
 // Defaults to enable various configurations of host bionic
 //
diff --git a/apex/apex.go b/apex/apex.go
index fd3fb2b..8463ac1 100644
--- a/apex/apex.go
+++ b/apex/apex.go
@@ -836,10 +836,13 @@
 // Mark the direct and transitive dependencies of apex bundles so that they
 // can be built for the apex bundles.
 func apexDepsMutator(mctx android.TopDownMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
 	var apexBundles []android.ApexInfo
 	var directDep bool
 	if a, ok := mctx.Module().(*apexBundle); ok && !a.vndkApex {
-		apexBundles = []android.ApexInfo{android.ApexInfo{
+		apexBundles = []android.ApexInfo{{
 			ApexName:      mctx.ModuleName(),
 			MinSdkVersion: a.minSdkVersion(mctx),
 		}}
@@ -877,6 +880,9 @@
 
 // Create apex variations if a module is included in APEX(s).
 func apexMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
 	if am, ok := mctx.Module().(android.ApexModule); ok && am.CanHaveApexVariants() {
 		am.CreateApexVariations(mctx)
 	} else if a, ok := mctx.Module().(*apexBundle); ok && !a.vndkApex {
@@ -914,6 +920,9 @@
 }
 
 func apexFlattenedMutator(mctx android.BottomUpMutatorContext) {
+	if !mctx.Module().Enabled() {
+		return
+	}
 	if ab, ok := mctx.Module().(*apexBundle); ok {
 		var variants []string
 		switch proptools.StringDefault(ab.properties.Payload_type, "image") {
@@ -1732,15 +1741,16 @@
 func apexFileForAndroidApp(ctx android.BaseModuleContext, aapp interface {
 	android.Module
 	Privileged() bool
+	InstallApkName() string
 	OutputFile() android.Path
 	JacocoReportClassesFile() android.Path
 	Certificate() java.Certificate
-}, pkgName string) apexFile {
+}) apexFile {
 	appDir := "app"
 	if aapp.Privileged() {
 		appDir = "priv-app"
 	}
-	dirInApex := filepath.Join(appDir, pkgName)
+	dirInApex := filepath.Join(appDir, aapp.InstallApkName())
 	fileToCopy := aapp.OutputFile()
 	af := newApexFile(ctx, fileToCopy, aapp.Name(), dirInApex, app, aapp)
 	af.jacocoReportClassesFile = aapp.JacocoReportClassesFile()
@@ -2031,14 +2041,13 @@
 					ctx.PropertyErrorf("java_libs", "%q of type %q is not supported", depName, ctx.OtherModuleType(child))
 				}
 			case androidAppTag:
-				pkgName := ctx.DeviceConfig().OverridePackageNameFor(depName)
 				if ap, ok := child.(*java.AndroidApp); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap, pkgName))
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
 					return true // track transitive dependencies
 				} else if ap, ok := child.(*java.AndroidAppImport); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap, pkgName))
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
 				} else if ap, ok := child.(*java.AndroidTestHelperApp); ok {
-					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap, pkgName))
+					filesInfo = append(filesInfo, apexFileForAndroidApp(ctx, ap))
 				} else {
 					ctx.PropertyErrorf("apps", "%q is not an android_app module", depName)
 				}
diff --git a/apex/apex_test.go b/apex/apex_test.go
index 0c8937e..9f55728 100644
--- a/apex/apex_test.go
+++ b/apex/apex_test.go
@@ -3438,6 +3438,7 @@
 			dex_preopt: {
 				enabled: false,
 			},
+			filename: "AwesomePrebuiltAppFooPriv.apk",
 		}
 	`)
 
@@ -3446,7 +3447,47 @@
 	copyCmds := apexRule.Args["copy_commands"]
 
 	ensureContains(t, copyCmds, "image.apex/app/AppFooPrebuilt/AppFooPrebuilt.apk")
-	ensureContains(t, copyCmds, "image.apex/priv-app/AppFooPrivPrebuilt/AppFooPrivPrebuilt.apk")
+	ensureContains(t, copyCmds, "image.apex/priv-app/AppFooPrivPrebuilt/AwesomePrebuiltAppFooPriv.apk")
+}
+
+func TestApexWithAppImportsPrefer(t *testing.T) {
+	ctx, _ := testApex(t, `
+		apex {
+			name: "myapex",
+			key: "myapex.key",
+			apps: [
+				"AppFoo",
+			],
+		}
+
+		apex_key {
+			name: "myapex.key",
+			public_key: "testkey.avbpubkey",
+			private_key: "testkey.pem",
+		}
+
+		android_app {
+			name: "AppFoo",
+			srcs: ["foo/bar/MyClass.java"],
+			sdk_version: "none",
+			system_modules: "none",
+			apex_available: [ "myapex" ],
+		}
+
+		android_app_import {
+			name: "AppFoo",
+			apk: "AppFooPrebuilt.apk",
+			filename: "AppFooPrebuilt.apk",
+			presigned: true,
+			prefer: true,
+		}
+	`, withFiles(map[string][]byte{
+		"AppFooPrebuilt.apk": nil,
+	}))
+
+	ensureExactContents(t, ctx, "myapex", "android_common_myapex_image", []string{
+		"app/AppFoo/AppFooPrebuilt.apk",
+	})
 }
 
 func TestApexWithTestHelperApp(t *testing.T) {
@@ -3779,7 +3820,7 @@
 	copyCmds := apexRule.Args["copy_commands"]
 
 	ensureNotContains(t, copyCmds, "image.apex/app/app/app.apk")
-	ensureContains(t, copyCmds, "image.apex/app/app/override_app.apk")
+	ensureContains(t, copyCmds, "image.apex/app/override_app/override_app.apk")
 
 	apexBundle := module.Module().(*apexBundle)
 	name := apexBundle.Name()
@@ -4151,6 +4192,27 @@
 	})
 }
 
+func TestApexMutatorsDontRunIfDisabled(t *testing.T) {
+	ctx, _ := testApex(t, `
+		apex {
+			name: "myapex",
+			key: "myapex.key",
+		}
+		apex_key {
+			name: "myapex.key",
+			public_key: "testkey.avbpubkey",
+			private_key: "testkey.pem",
+		}
+	`, func(fs map[string][]byte, config android.Config) {
+		delete(config.Targets, android.Android)
+		config.AndroidCommonTarget = android.Target{}
+	})
+
+	if expected, got := []string{""}, ctx.ModuleVariantsForTests("myapex"); !reflect.DeepEqual(expected, got) {
+		t.Errorf("Expected variants: %v, but got: %v", expected, got)
+	}
+}
+
 func TestApexWithJniLibs_Errors(t *testing.T) {
 	testApexError(t, `jni_libs: "xxx" is not a cc_library`, `
 		apex {
diff --git a/cc/builder.go b/cc/builder.go
index 136263b..d8e90b6 100644
--- a/cc/builder.go
+++ b/cc/builder.go
@@ -29,6 +29,7 @@
 
 	"android/soong/android"
 	"android/soong/cc/config"
+	"android/soong/remoteexec"
 )
 
 const (
@@ -62,7 +63,7 @@
 		},
 		"ccCmd", "cFlags")
 
-	ld = pctx.AndroidStaticRule("ld",
+	ld, ldRE = remoteexec.StaticRules(pctx, "ld",
 		blueprint.RuleParams{
 			Command: "$ldCmd ${crtBegin} @${out}.rsp " +
 				"${libFlags} ${crtEnd} -o ${out} ${ldFlags} ${extraLibFlags}",
@@ -72,16 +73,28 @@
 			// clang -Wl,--out-implib doesn't update its output file if it hasn't changed.
 			Restat: true,
 		},
-		"ldCmd", "crtBegin", "libFlags", "crtEnd", "ldFlags", "extraLibFlags")
+		&remoteexec.REParams{Labels: map[string]string{"type": "link", "tool": "clang"},
+			ExecStrategy:    "${config.RECXXLinksExecStrategy}",
+			Inputs:          []string{"${out}.rsp"},
+			RSPFile:         "${out}.rsp",
+			OutputFiles:     []string{"${out}"},
+			ToolchainInputs: []string{"$ldCmd"},
+			Platform:        map[string]string{remoteexec.PoolKey: "${config.RECXXLinksPool}"},
+		}, []string{"ldCmd", "crtBegin", "libFlags", "crtEnd", "ldFlags", "extraLibFlags"}, nil)
 
-	partialLd = pctx.AndroidStaticRule("partialLd",
+	partialLd, partialLdRE = remoteexec.StaticRules(pctx, "partialLd",
 		blueprint.RuleParams{
 			// Without -no-pie, clang 7.0 adds -pie to link Android files,
 			// but -r and -pie cannot be used together.
 			Command:     "$ldCmd -fuse-ld=lld -nostdlib -no-pie -Wl,-r ${in} -o ${out} ${ldFlags}",
 			CommandDeps: []string{"$ldCmd"},
-		},
-		"ldCmd", "ldFlags")
+		}, &remoteexec.REParams{
+			Labels:       map[string]string{"type": "link", "tool": "clang"},
+			ExecStrategy: "${config.RECXXLinksExecStrategy}", Inputs: []string{"$inCommaList"},
+			OutputFiles:     []string{"${out}"},
+			ToolchainInputs: []string{"$ldCmd"},
+			Platform:        map[string]string{remoteexec.PoolKey: "${config.RECXXLinksPool}"},
+		}, []string{"ldCmd", "ldFlags"}, []string{"inCommaList"})
 
 	ar = pctx.AndroidStaticRule("ar",
 		blueprint.RuleParams{
@@ -262,6 +275,7 @@
 	}
 
 	pctx.HostBinToolVariable("SoongZipCmd", "soong_zip")
+	pctx.Import("android/soong/remoteexec")
 }
 
 type builderFlags struct {
@@ -293,7 +307,7 @@
 	rsFlags       string
 	toolchain     config.Toolchain
 	tidy          bool
-	coverage      bool
+	gcovCoverage  bool
 	sAbiDump      bool
 	emitXrefs     bool
 
@@ -355,7 +369,7 @@
 		tidyFiles = make(android.Paths, 0, len(srcFiles))
 	}
 	var coverageFiles android.Paths
-	if flags.coverage {
+	if flags.gcovCoverage {
 		coverageFiles = make(android.Paths, 0, len(srcFiles))
 	}
 	var kytheFiles android.Paths
@@ -456,7 +470,7 @@
 
 		var ccCmd string
 		tidy := flags.tidy
-		coverage := flags.coverage
+		coverage := flags.gcovCoverage
 		dump := flags.sAbiDump
 		rule := cc
 		emitXref := flags.emitXrefs
@@ -657,8 +671,13 @@
 		deps = append(deps, crtBegin.Path(), crtEnd.Path())
 	}
 
+	rule := ld
+	if ctx.Config().IsEnvTrue("RBE_CXX_LINKS") {
+		rule = ldRE
+	}
+
 	ctx.Build(pctx, android.BuildParams{
-		Rule:            ld,
+		Rule:            rule,
 		Description:     "link " + outputFile.Base(),
 		Output:          outputFile,
 		ImplicitOutputs: implicitOutputs,
@@ -798,16 +817,22 @@
 
 	ldCmd := "${config.ClangBin}/clang++"
 
+	rule := partialLd
+	args := map[string]string{
+		"ldCmd":   ldCmd,
+		"ldFlags": flags.globalLdFlags + " " + flags.localLdFlags,
+	}
+	if ctx.Config().IsEnvTrue("RBE_CXX_LINKS") {
+		rule = partialLdRE
+		args["inCommaList"] = strings.Join(objFiles.Strings(), ",")
+	}
 	ctx.Build(pctx, android.BuildParams{
-		Rule:        partialLd,
+		Rule:        rule,
 		Description: "link " + outputFile.Base(),
 		Output:      outputFile,
 		Inputs:      objFiles,
 		Implicits:   deps,
-		Args: map[string]string{
-			"ldCmd":   ldCmd,
-			"ldFlags": flags.globalLdFlags + " " + flags.localLdFlags,
-		},
+		Args:        args,
 	})
 }
 
diff --git a/cc/cc.go b/cc/cc.go
index 0201404..24173ee 100644
--- a/cc/cc.go
+++ b/cc/cc.go
@@ -182,11 +182,11 @@
 	// These must be after any module include flags, which will be in CommonFlags.
 	SystemIncludeFlags []string
 
-	Toolchain config.Toolchain
-	Tidy      bool
-	Coverage  bool
-	SAbiDump  bool
-	EmitXrefs bool // If true, generate Ninja rules to generate emitXrefs input files for Kythe
+	Toolchain    config.Toolchain
+	Tidy         bool
+	GcovCoverage bool
+	SAbiDump     bool
+	EmitXrefs    bool // If true, generate Ninja rules to generate emitXrefs input files for Kythe
 
 	RequiredInstructionSet string
 	DynamicLinker          string
@@ -213,6 +213,9 @@
 	// two variants to be built, one for the platform and one for apps.
 	Sdk_version *string
 
+	// Minimum sdk version that the artifact should support when it runs as part of mainline modules(APEX).
+	Min_sdk_version *string
+
 	// If true, always create an sdk variant and don't create a platform variant.
 	Sdk_variant_only *bool
 
@@ -1195,6 +1198,11 @@
 		return false
 	}
 
+	// Coverage builds have extra symbols.
+	if ctx.mod.isCoverageVariant() {
+		return false
+	}
+
 	if ctx.ctx.Fuchsia() {
 		return false
 	}
@@ -1901,8 +1909,7 @@
 	addSharedLibDependencies := func(depTag DependencyTag, name string, version string) {
 		var variations []blueprint.Variation
 		variations = append(variations, blueprint.Variation{Mutator: "link", Variation: "shared"})
-		versionVariantAvail := !c.InRecovery() && !c.InRamdisk()
-		if version != "" && versionVariantAvail {
+		if version != "" && VersionVariantAvailable(c) {
 			// Version is explicitly specified. i.e. libFoo#30
 			variations = append(variations, blueprint.Variation{Mutator: "version", Variation: version})
 			depTag.ExplicitlyVersioned = true
@@ -1912,7 +1919,7 @@
 		// If the version is not specified, add dependency to all stubs libraries.
 		// The stubs library will be used when the depending module is built for APEX and
 		// the dependent module is not in the same APEX.
-		if version == "" && versionVariantAvail {
+		if version == "" && VersionVariantAvailable(c) {
 			for _, ver := range stubsVersionsFor(actx.Config())[name] {
 				// Note that depTag.ExplicitlyVersioned is false in this case.
 				actx.AddVariationDependencies([]blueprint.Variation{
@@ -2310,7 +2317,7 @@
 			}
 			if ccDep.CcLibrary() && !depIsStatic {
 				depIsStubs := ccDep.BuildStubs()
-				depHasStubs := ccDep.HasStubsVariants()
+				depHasStubs := VersionVariantAvailable(c) && ccDep.HasStubsVariants()
 				depInSameApex := android.DirectlyInApex(c.ApexName(), depName)
 				depInPlatform := !android.DirectlyInAnyApex(ctx, depName)
 
@@ -2326,8 +2333,8 @@
 					// If not building for APEX, use stubs only when it is from
 					// an APEX (and not from platform)
 					useThisDep = (depInPlatform != depIsStubs)
-					if c.InRamdisk() || c.InRecovery() || c.bootstrap() {
-						// However, for ramdisk, recovery or bootstrap modules,
+					if c.bootstrap() {
+						// However, for host, ramdisk, recovery or bootstrap modules,
 						// always link to non-stub variant
 						useThisDep = !depIsStubs
 					}
diff --git a/cc/config/global.go b/cc/config/global.go
index 5611a96..d85ac5f 100644
--- a/cc/config/global.go
+++ b/cc/config/global.go
@@ -18,6 +18,7 @@
 	"strings"
 
 	"android/soong/android"
+	"android/soong/remoteexec"
 )
 
 var (
@@ -255,6 +256,9 @@
 		}
 		return ""
 	})
+
+	pctx.VariableFunc("RECXXLinksPool", envOverrideFunc("RBE_CXX_LINKS_POOL", remoteexec.DefaultPool))
+	pctx.VariableFunc("RECXXLinksExecStrategy", envOverrideFunc("RBE_CXX_LINKS_EXEC_STRATEGY", remoteexec.LocalExecStrategy))
 }
 
 var HostPrebuiltTag = pctx.VariableConfigMethod("HostPrebuiltTag", android.Config.PrebuiltOS)
@@ -268,3 +272,12 @@
 		"-isystem bionic/libc/kernel/android/uapi",
 	}, " ")
 }
+
+func envOverrideFunc(envVar, defaultVal string) func(ctx android.PackageVarContext) string {
+	return func(ctx android.PackageVarContext) string {
+		if override := ctx.Config().Getenv(envVar); override != "" {
+			return override
+		}
+		return defaultVal
+	}
+}
diff --git a/cc/coverage.go b/cc/coverage.go
index b94b628..bde07fd 100644
--- a/cc/coverage.go
+++ b/cc/coverage.go
@@ -82,10 +82,10 @@
 	}
 
 	if cov.Properties.CoverageEnabled {
-		flags.Coverage = true
 		cov.linkCoverage = true
 
 		if gcovCoverage {
+			flags.GcovCoverage = true
 			flags.Local.CommonFlags = append(flags.Local.CommonFlags, "--coverage", "-O0")
 
 			// Override -Wframe-larger-than and non-default optimization
diff --git a/cc/library.go b/cc/library.go
index 94fffb9..e79d9bd 100644
--- a/cc/library.go
+++ b/cc/library.go
@@ -1528,10 +1528,18 @@
 	}
 }
 
-// Version mutator splits a module into the mandatory non-stubs variant
+func VersionVariantAvailable(module interface {
+	Host() bool
+	InRamdisk() bool
+	InRecovery() bool
+}) bool {
+	return !module.Host() && !module.InRamdisk() && !module.InRecovery()
+}
+
+// VersionMutator splits a module into the mandatory non-stubs variant
 // (which is unnamed) and zero or more stubs variants.
 func VersionMutator(mctx android.BottomUpMutatorContext) {
-	if library, ok := mctx.Module().(LinkableInterface); ok && !library.InRecovery() {
+	if library, ok := mctx.Module().(LinkableInterface); ok && VersionVariantAvailable(library) {
 		if library.CcLibrary() && library.BuildSharedVariant() && len(library.StubsVersions()) > 0 {
 			versions := library.StubsVersions()
 			checkVersions(mctx, versions)
@@ -1567,7 +1575,7 @@
 	}
 	if genrule, ok := mctx.Module().(*genrule.Module); ok {
 		if _, ok := genrule.Extra.(*GenruleExtraProperties); ok {
-			if !genrule.InRecovery() {
+			if VersionVariantAvailable(genrule) {
 				mctx.CreateVariations("")
 				return
 			}
diff --git a/cc/linkable.go b/cc/linkable.go
index fbe61a4..4a70d48 100644
--- a/cc/linkable.go
+++ b/cc/linkable.go
@@ -39,6 +39,8 @@
 	Shared() bool
 	Toc() android.OptionalPath
 
+	Host() bool
+
 	InRamdisk() bool
 	OnlyInRamdisk() bool
 
diff --git a/cc/prebuilt.go b/cc/prebuilt.go
index 2ef3195..ac990f3 100644
--- a/cc/prebuilt.go
+++ b/cc/prebuilt.go
@@ -43,6 +43,11 @@
 	// Check the prebuilt ELF files (e.g. DT_SONAME, DT_NEEDED, resolution of undefined
 	// symbols, etc), default true.
 	Check_elf_files *bool
+
+	// Optionally provide an import library if this is a Windows PE DLL prebuilt.
+	// This is needed only if this library is linked by other modules in build time.
+	// Only makes sense for the Windows target.
+	Windows_import_lib *string `android:"path,arch_variant"`
 }
 
 type prebuiltLinker struct {
@@ -109,9 +114,16 @@
 
 		in := android.PathForModuleSrc(ctx, srcs[0])
 
+		if p.static() {
+			return in
+		}
+
 		if p.shared() {
 			p.unstrippedOutputFile = in
 			libName := p.libraryDecorator.getLibName(ctx) + flags.Toolchain.ShlibSuffix()
+			outputFile := android.PathForModuleOut(ctx, libName)
+			var implicits android.Paths
+
 			if p.needsStrip(ctx) {
 				stripped := android.PathForModuleOut(ctx, "stripped", libName)
 				p.stripExecutableOrSharedLib(ctx, in, stripped, builderFlags)
@@ -122,10 +134,41 @@
 			// depending on a table of contents file instead of the library itself.
 			tocFile := android.PathForModuleOut(ctx, libName+".toc")
 			p.tocFile = android.OptionalPathForPath(tocFile)
-			TransformSharedObjectToToc(ctx, in, tocFile, builderFlags)
-		}
+			TransformSharedObjectToToc(ctx, outputFile, tocFile, builderFlags)
 
-		return in
+			if ctx.Windows() && p.properties.Windows_import_lib != nil {
+				// Consumers of this library actually links to the import library in build
+				// time and dynamically links to the DLL in run time. i.e.
+				// a.exe <-- static link --> foo.lib <-- dynamic link --> foo.dll
+				importLibSrc := android.PathForModuleSrc(ctx, String(p.properties.Windows_import_lib))
+				importLibName := p.libraryDecorator.getLibName(ctx) + ".lib"
+				importLibOutputFile := android.PathForModuleOut(ctx, importLibName)
+				implicits = append(implicits, importLibOutputFile)
+
+				ctx.Build(pctx, android.BuildParams{
+					Rule:        android.Cp,
+					Description: "prebuilt import library",
+					Input:       importLibSrc,
+					Output:      importLibOutputFile,
+					Args: map[string]string{
+						"cpFlags": "-L",
+					},
+				})
+			}
+
+			ctx.Build(pctx, android.BuildParams{
+				Rule:        android.Cp,
+				Description: "prebuilt shared library",
+				Implicits:   implicits,
+				Input:       in,
+				Output:      outputFile,
+				Args: map[string]string{
+					"cpFlags": "-L",
+				},
+			})
+
+			return outputFile
+		}
 	}
 
 	return nil
diff --git a/cc/prebuilt_test.go b/cc/prebuilt_test.go
index 0b018c1..adb44bd 100644
--- a/cc/prebuilt_test.go
+++ b/cc/prebuilt_test.go
@@ -184,7 +184,7 @@
 	})
 
 	shared := ctx.ModuleForTests("libtest", "android_arm64_armv8-a_shared").Module().(*Module)
-	assertString(t, shared.OutputFile().String(), "libf.so")
+	assertString(t, shared.OutputFile().Path().Base(), "libtest.so")
 }
 
 func TestPrebuiltLibraryStatic(t *testing.T) {
@@ -198,7 +198,7 @@
 	})
 
 	static := ctx.ModuleForTests("libtest", "android_arm64_armv8-a_static").Module().(*Module)
-	assertString(t, static.OutputFile().String(), "libf.a")
+	assertString(t, static.OutputFile().Path().Base(), "libf.a")
 }
 
 func TestPrebuiltLibrary(t *testing.T) {
@@ -221,8 +221,53 @@
 	})
 
 	shared := ctx.ModuleForTests("libtest", "android_arm64_armv8-a_shared").Module().(*Module)
-	assertString(t, shared.OutputFile().String(), "libf.so")
+	assertString(t, shared.OutputFile().Path().Base(), "libtest.so")
 
 	static := ctx.ModuleForTests("libtest", "android_arm64_armv8-a_static").Module().(*Module)
-	assertString(t, static.OutputFile().String(), "libf.a")
+	assertString(t, static.OutputFile().Path().Base(), "libf.a")
+}
+
+func TestPrebuiltLibraryStem(t *testing.T) {
+	ctx := testPrebuilt(t, `
+	cc_prebuilt_library {
+		name: "libfoo",
+		stem: "libbar",
+		static: {
+			srcs: ["libfoo.a"],
+		},
+		shared: {
+			srcs: ["libfoo.so"],
+		},
+		strip: {
+			none: true,
+		},
+	}
+	`, map[string][]byte{
+		"libfoo.a":  nil,
+		"libfoo.so": nil,
+	})
+
+	static := ctx.ModuleForTests("libfoo", "android_arm64_armv8-a_static").Module().(*Module)
+	assertString(t, static.OutputFile().Path().Base(), "libfoo.a")
+
+	shared := ctx.ModuleForTests("libfoo", "android_arm64_armv8-a_shared").Module().(*Module)
+	assertString(t, shared.OutputFile().Path().Base(), "libbar.so")
+}
+
+func TestPrebuiltLibrarySharedStem(t *testing.T) {
+	ctx := testPrebuilt(t, `
+	cc_prebuilt_library_shared {
+		name: "libfoo",
+		stem: "libbar",
+		srcs: ["libfoo.so"],
+		strip: {
+			none: true,
+		},
+	}
+	`, map[string][]byte{
+		"libfoo.so": nil,
+	})
+
+	shared := ctx.ModuleForTests("libfoo", "android_arm64_armv8-a_shared").Module().(*Module)
+	assertString(t, shared.OutputFile().Path().Base(), "libbar.so")
 }
diff --git a/cc/util.go b/cc/util.go
index 60070bb..af26268 100644
--- a/cc/util.go
+++ b/cc/util.go
@@ -82,7 +82,7 @@
 		tidyFlags:     strings.Join(in.TidyFlags, " "),
 		sAbiFlags:     strings.Join(in.SAbiFlags, " "),
 		toolchain:     in.Toolchain,
-		coverage:      in.Coverage,
+		gcovCoverage:  in.GcovCoverage,
 		tidy:          in.Tidy,
 		sAbiDump:      in.SAbiDump,
 		emitXrefs:     in.EmitXrefs,
diff --git a/java/androidmk.go b/java/androidmk.go
index bbf2c33..7d57525 100644
--- a/java/androidmk.go
+++ b/java/androidmk.go
@@ -588,14 +588,12 @@
 					fmt.Fprintln(w, dstubs.Name()+"-check-last-released-api:",
 						dstubs.checkLastReleasedApiTimestamp.String())
 
-					if dstubs.Name() != "android.car-system-stubs-docs" {
-						fmt.Fprintln(w, ".PHONY: checkapi")
-						fmt.Fprintln(w, "checkapi:",
-							dstubs.checkLastReleasedApiTimestamp.String())
+					fmt.Fprintln(w, ".PHONY: checkapi")
+					fmt.Fprintln(w, "checkapi:",
+						dstubs.checkLastReleasedApiTimestamp.String())
 
-						fmt.Fprintln(w, ".PHONY: droidcore")
-						fmt.Fprintln(w, "droidcore: checkapi")
-					}
+					fmt.Fprintln(w, ".PHONY: droidcore")
+					fmt.Fprintln(w, "droidcore: checkapi")
 				}
 				if dstubs.apiLintTimestamp != nil {
 					fmt.Fprintln(w, ".PHONY:", dstubs.Name()+"-api-lint")
diff --git a/java/app.go b/java/app.go
index ac5121a..7d509ee 100755
--- a/java/app.go
+++ b/java/app.go
@@ -511,6 +511,10 @@
 	return certificates
 }
 
+func (a *AndroidApp) InstallApkName() string {
+	return a.installApkName
+}
+
 func (a *AndroidApp) generateAndroidBuildActions(ctx android.ModuleContext) {
 	var apkDeps android.Paths
 
@@ -1134,6 +1138,10 @@
 	a.generateAndroidBuildActions(ctx)
 }
 
+func (a *AndroidAppImport) InstallApkName() string {
+	return a.BaseModuleName()
+}
+
 func (a *AndroidAppImport) generateAndroidBuildActions(ctx android.ModuleContext) {
 	numCertPropsSet := 0
 	if String(a.properties.Certificate) != "" {
@@ -1191,6 +1199,8 @@
 		dexOutput = dexUncompressed
 	}
 
+	apkFilename := proptools.StringDefault(a.properties.Filename, a.BaseModuleName()+".apk")
+
 	// Sign or align the package
 	// TODO: Handle EXTERNAL
 	if !Bool(a.properties.Presigned) {
@@ -1201,11 +1211,11 @@
 			ctx.ModuleErrorf("Unexpected number of certificates were extracted: %q", certificates)
 		}
 		a.certificate = certificates[0]
-		signed := android.PathForModuleOut(ctx, "signed", ctx.ModuleName()+".apk")
+		signed := android.PathForModuleOut(ctx, "signed", apkFilename)
 		SignAppPackage(ctx, signed, dexOutput, certificates, nil)
 		a.outputFile = signed
 	} else {
-		alignedApk := android.PathForModuleOut(ctx, "zip-aligned", ctx.ModuleName()+".apk")
+		alignedApk := android.PathForModuleOut(ctx, "zip-aligned", apkFilename)
 		TransformZipAlign(ctx, alignedApk, dexOutput)
 		a.outputFile = alignedApk
 		a.certificate = presignedCertificate
@@ -1213,8 +1223,7 @@
 
 	// TODO: Optionally compress the output apk.
 
-	a.installPath = ctx.InstallFile(installDir,
-		proptools.StringDefault(a.properties.Filename, a.BaseModuleName()+".apk"), a.outputFile)
+	a.installPath = ctx.InstallFile(installDir, apkFilename, a.outputFile)
 
 	// TODO: androidmk converter jni libs
 }
diff --git a/java/builder.go b/java/builder.go
index 3a0247d..98f70cd 100644
--- a/java/builder.go
+++ b/java/builder.go
@@ -147,7 +147,12 @@
 
 	jarjar = pctx.AndroidStaticRule("jarjar",
 		blueprint.RuleParams{
-			Command:     "${config.JavaCmd} ${config.JavaVmFlags} -jar ${config.JarjarCmd} process $rulesFile $in $out",
+			Command: "${config.JavaCmd} ${config.JavaVmFlags}" +
+				// b/146418363 Enable Android specific jarjar transformer to drop compat annotations
+				// for newly repackaged classes. Dropping @UnsupportedAppUsage on repackaged classes
+				// avoids adding new hiddenapis after jarjar'ing.
+				" -DremoveAndroidCompatAnnotations=true" +
+				" -jar ${config.JarjarCmd} process $rulesFile $in $out",
 			CommandDeps: []string{"${config.JavaCmd}", "${config.JarjarCmd}", "$rulesFile"},
 		},
 		"rulesFile")
diff --git a/remoteexec/remoteexec.go b/remoteexec/remoteexec.go
new file mode 100644
index 0000000..d43dc6c
--- /dev/null
+++ b/remoteexec/remoteexec.go
@@ -0,0 +1,155 @@
+// Copyright 2020 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 remoteexec
+
+import (
+	"sort"
+	"strings"
+
+	"android/soong/android"
+
+	"github.com/google/blueprint"
+)
+
+const (
+	// ContainerImageKey is the key identifying the container image in the platform spec.
+	ContainerImageKey = "container-image"
+
+	// PoolKey is the key identifying the pool to use for remote execution.
+	PoolKey = "Pool"
+
+	// DefaultImage is the default container image used for Android remote execution. The
+	// image was built with the Dockerfile at
+	// https://android.googlesource.com/platform/prebuilts/remoteexecution-client/+/refs/heads/master/docker/Dockerfile
+	DefaultImage = "docker://gcr.io/androidbuild-re-dockerimage/android-build-remoteexec-image@sha256:582efb38f0c229ea39952fff9e132ccbe183e14869b39888010dacf56b360d62"
+
+	// DefaultWrapperPath is the default path to the remote execution wrapper.
+	DefaultWrapperPath = "prebuilts/remoteexecution-client/live/rewrapper"
+
+	// DefaultPool is the name of the pool to use for remote execution when none is specified.
+	DefaultPool = "default"
+
+	// LocalExecStrategy is the exec strategy to indicate that the action should be run locally.
+	LocalExecStrategy = "local"
+
+	// RemoteExecStrategy is the exec strategy to indicate that the action should be run
+	// remotely.
+	RemoteExecStrategy = "remote"
+
+	// RemoteLocalFallbackExecStrategy is the exec strategy to indicate that the action should
+	// be run remotely and fallback to local execution if remote fails.
+	RemoteLocalFallbackExecStrategy = "remote_local_fallback"
+)
+
+var (
+	defaultLabels       = map[string]string{"type": "tool"}
+	defaultExecStrategy = LocalExecStrategy
+	pctx                = android.NewPackageContext("android/soong/remoteexec")
+)
+
+// REParams holds information pertinent to the remote execution of a rule.
+type REParams struct {
+	// Platform is the key value pair used for remotely executing the action.
+	Platform map[string]string
+	// Labels is a map of labels that identify the rule.
+	Labels map[string]string
+	// ExecStrategy is the remote execution strategy: remote, local, or remote_local_fallback.
+	ExecStrategy string
+	// Inputs is a list of input paths or ninja variables.
+	Inputs []string
+	// RSPFile is the name of the ninja variable used by the rule as a placeholder for an rsp
+	// input.
+	RSPFile string
+	// OutputFiles is a list of output file paths or ninja variables as placeholders for rule
+	// outputs.
+	OutputFiles []string
+	// ToolchainInputs is a list of paths or ninja variables pointing to the location of
+	// toolchain binaries used by the rule.
+	ToolchainInputs []string
+}
+
+func init() {
+	pctx.VariableFunc("Wrapper", func(ctx android.PackageVarContext) string {
+		if override := ctx.Config().Getenv("RBE_WRAPPER"); override != "" {
+			return override
+		}
+		return DefaultWrapperPath
+	})
+}
+
+// Generate the remote execution wrapper template to be added as a prefix to the rule's command.
+func (r *REParams) Template() string {
+	template := "${remoteexec.Wrapper}"
+
+	var kvs []string
+	labels := r.Labels
+	if len(labels) == 0 {
+		labels = defaultLabels
+	}
+	for k, v := range labels {
+		kvs = append(kvs, k+"="+v)
+	}
+	sort.Strings(kvs)
+	template += " --labels=" + strings.Join(kvs, ",")
+
+	var platform []string
+	for k, v := range r.Platform {
+		if v == "" {
+			continue
+		}
+		platform = append(platform, k+"="+v)
+	}
+	if _, ok := r.Platform[ContainerImageKey]; !ok {
+		platform = append(platform, ContainerImageKey+"="+DefaultImage)
+	}
+	if platform != nil {
+		sort.Strings(platform)
+		template += " --platform=\"" + strings.Join(platform, ",") + "\""
+	}
+
+	strategy := r.ExecStrategy
+	if strategy == "" {
+		strategy = defaultExecStrategy
+	}
+	template += " --exec_strategy=" + strategy
+
+	if len(r.Inputs) > 0 {
+		template += " --inputs=" + strings.Join(r.Inputs, ",")
+	}
+
+	if r.RSPFile != "" {
+		template += " --input_list_paths=" + r.RSPFile
+	}
+
+	if len(r.OutputFiles) > 0 {
+		template += " --output_files=" + strings.Join(r.OutputFiles, ",")
+	}
+
+	if len(r.ToolchainInputs) > 0 {
+		template += " --toolchain_inputs=" + strings.Join(r.ToolchainInputs, ",")
+	}
+
+	return template + " -- "
+}
+
+// StaticRules returns a pair of rules based on the given RuleParams, where the first rule is a
+// locally executable rule and the second rule is a remotely executable rule.
+func StaticRules(ctx android.PackageContext, name string, ruleParams blueprint.RuleParams, reParams *REParams, commonArgs []string, reArgs []string) (blueprint.Rule, blueprint.Rule) {
+	ruleParamsRE := ruleParams
+	ruleParamsRE.Command = reParams.Template() + ruleParamsRE.Command
+
+	return ctx.AndroidStaticRule(name, ruleParams, commonArgs...),
+		ctx.AndroidRemoteStaticRule(name+"RE", android.RemoteRuleSupports{RBE: true}, ruleParamsRE, append(commonArgs, reArgs...)...)
+}
diff --git a/remoteexec/remoteexec_test.go b/remoteexec/remoteexec_test.go
new file mode 100644
index 0000000..30e891c
--- /dev/null
+++ b/remoteexec/remoteexec_test.go
@@ -0,0 +1,83 @@
+// Copyright 2020 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 remoteexec
+
+import (
+	"fmt"
+	"testing"
+)
+
+func TestTemplate(t *testing.T) {
+	tests := []struct {
+		name   string
+		params *REParams
+		want   string
+	}{
+		{
+			name: "basic",
+			params: &REParams{
+				Labels:      map[string]string{"type": "compile", "lang": "cpp", "compiler": "clang"},
+				Inputs:      []string{"$in"},
+				OutputFiles: []string{"$out"},
+				Platform: map[string]string{
+					ContainerImageKey: DefaultImage,
+					PoolKey:           "default",
+				},
+			},
+			want: fmt.Sprintf("${remoteexec.Wrapper} --labels=compiler=clang,lang=cpp,type=compile --platform=\"Pool=default,container-image=%s\" --exec_strategy=local --inputs=$in --output_files=$out -- ", DefaultImage),
+		},
+		{
+			name: "all params",
+			params: &REParams{
+				Labels:          map[string]string{"type": "compile", "lang": "cpp", "compiler": "clang"},
+				Inputs:          []string{"$in"},
+				OutputFiles:     []string{"$out"},
+				ExecStrategy:    "remote",
+				RSPFile:         "$out.rsp",
+				ToolchainInputs: []string{"clang++"},
+				Platform: map[string]string{
+					ContainerImageKey: DefaultImage,
+					PoolKey:           "default",
+				},
+			},
+			want: fmt.Sprintf("${remoteexec.Wrapper} --labels=compiler=clang,lang=cpp,type=compile --platform=\"Pool=default,container-image=%s\" --exec_strategy=remote --inputs=$in --input_list_paths=$out.rsp --output_files=$out --toolchain_inputs=clang++ -- ", DefaultImage),
+		},
+	}
+	for _, test := range tests {
+		t.Run(test.name, func(t *testing.T) {
+			if got := test.params.Template(); got != test.want {
+				t.Errorf("Template() returned\n%s\nwant\n%s", got, test.want)
+			}
+		})
+	}
+}
+
+func TestTemplateDeterminism(t *testing.T) {
+	r := &REParams{
+		Labels:      map[string]string{"type": "compile", "lang": "cpp", "compiler": "clang"},
+		Inputs:      []string{"$in"},
+		OutputFiles: []string{"$out"},
+		Platform: map[string]string{
+			ContainerImageKey: DefaultImage,
+			PoolKey:           "default",
+		},
+	}
+	want := fmt.Sprintf("${remoteexec.Wrapper} --labels=compiler=clang,lang=cpp,type=compile --platform=\"Pool=default,container-image=%s\" --exec_strategy=local --inputs=$in --output_files=$out -- ", DefaultImage)
+	for i := 0; i < 1000; i++ {
+		if got := r.Template(); got != want {
+			t.Fatalf("Template() returned\n%s\nwant\n%s", got, want)
+		}
+	}
+}
diff --git a/rust/rust.go b/rust/rust.go
index 6fe8871..5cc8845 100644
--- a/rust/rust.go
+++ b/rust/rust.go
@@ -735,13 +735,14 @@
 
 	deps := mod.deps(ctx)
 	commonDepVariations := []blueprint.Variation{}
-	commonDepVariations = append(commonDepVariations,
-		blueprint.Variation{Mutator: "version", Variation: ""})
+	if cc.VersionVariantAvailable(mod) {
+		commonDepVariations = append(commonDepVariations,
+			blueprint.Variation{Mutator: "version", Variation: ""})
+	}
 	if !mod.Host() {
 		commonDepVariations = append(commonDepVariations,
 			blueprint.Variation{Mutator: "image", Variation: android.CoreVariation})
 	}
-
 	actx.AddVariationDependencies(
 		append(commonDepVariations, []blueprint.Variation{
 			{Mutator: "rust_libraries", Variation: "rlib"},
diff --git a/sysprop/sysprop_library.go b/sysprop/sysprop_library.go
index a2e35d9..0932873 100644
--- a/sysprop/sysprop_library.go
+++ b/sysprop/sysprop_library.go
@@ -151,6 +151,12 @@
 
 	// Whether public stub exists or not.
 	Public_stub *bool `blueprint:"mutated"`
+
+	Cpp struct {
+		// Minimum sdk version that the artifact should support when it runs as part of mainline modules(APEX).
+		// Forwarded to cc_library.min_sdk_version
+		Min_sdk_version *string
+	}
 }
 
 var (
@@ -344,6 +350,7 @@
 	Vendor_available   *bool
 	Host_supported     *bool
 	Apex_available     []string
+	Min_sdk_version    *string
 }
 
 type javaLibraryProperties struct {
@@ -433,6 +440,7 @@
 	ccProps.Vendor_available = m.properties.Vendor_available
 	ccProps.Host_supported = m.properties.Host_supported
 	ccProps.Apex_available = m.ApexProperties.Apex_available
+	ccProps.Min_sdk_version = m.properties.Cpp.Min_sdk_version
 	ctx.CreateModule(cc.LibraryFactory, &ccProps)
 
 	scope := "internal"
diff --git a/ui/build/build.go b/ui/build/build.go
index f3feac2..1122733 100644
--- a/ui/build/build.go
+++ b/ui/build/build.go
@@ -53,7 +53,6 @@
 {{end -}}
 pool highmem_pool
  depth = {{.HighmemParallel}}
-build _kati_always_build_: phony
 {{if .HasKatiSuffix}}subninja {{.KatiBuildNinjaFile}}
 subninja {{.KatiPackageNinjaFile}}
 {{end -}}
diff --git a/ui/build/dumpvars.go b/ui/build/dumpvars.go
index ce8f968..a559330 100644
--- a/ui/build/dumpvars.go
+++ b/ui/build/dumpvars.go
@@ -190,6 +190,7 @@
 		// compiler wrappers set up by make
 		"CC_WRAPPER",
 		"CXX_WRAPPER",
+		"RBE_WRAPPER",
 		"JAVAC_WRAPPER",
 		"R8_WRAPPER",
 		"D8_WRAPPER",
@@ -228,8 +229,6 @@
 		"DEFAULT_ERROR_BUILD_MODULE_TYPES",
 		"BUILD_BROKEN_PREBUILT_ELF_FILES",
 		"BUILD_BROKEN_TREBLE_SYSPROP_NEVERALLOW",
-		"BUILD_BROKEN_USES_BUILD_AUX_EXECUTABLE",
-		"BUILD_BROKEN_USES_BUILD_AUX_STATIC_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_COPY_HEADERS",
 		"BUILD_BROKEN_USES_BUILD_EXECUTABLE",
 		"BUILD_BROKEN_USES_BUILD_FUZZ_TEST",
@@ -237,17 +236,12 @@
 		"BUILD_BROKEN_USES_BUILD_HOST_DALVIK_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_HOST_DALVIK_STATIC_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_HOST_EXECUTABLE",
-		"BUILD_BROKEN_USES_BUILD_HOST_FUZZ_TEST",
 		"BUILD_BROKEN_USES_BUILD_HOST_JAVA_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_HOST_NATIVE_TEST",
 		"BUILD_BROKEN_USES_BUILD_HOST_PREBUILT",
 		"BUILD_BROKEN_USES_BUILD_HOST_SHARED_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_HOST_STATIC_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_HOST_STATIC_TEST_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_HOST_TEST_CONFIG",
 		"BUILD_BROKEN_USES_BUILD_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_MULTI_PREBUILT",
-		"BUILD_BROKEN_USES_BUILD_NATIVE_BENCHMARK",
 		"BUILD_BROKEN_USES_BUILD_NATIVE_TEST",
 		"BUILD_BROKEN_USES_BUILD_NOTICE_FILE",
 		"BUILD_BROKEN_USES_BUILD_PACKAGE",
@@ -257,8 +251,6 @@
 		"BUILD_BROKEN_USES_BUILD_SHARED_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_STATIC_JAVA_LIBRARY",
 		"BUILD_BROKEN_USES_BUILD_STATIC_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_STATIC_TEST_LIBRARY",
-		"BUILD_BROKEN_USES_BUILD_TARGET_TEST_CONFIG",
 	}, exportEnvVars...), BannerVars...)
 
 	make_vars, err := dumpMakeVars(ctx, config, config.Arguments(), allVars, true)
diff --git a/ui/build/exec.go b/ui/build/exec.go
index e435c53..053bbae 100644
--- a/ui/build/exec.go
+++ b/ui/build/exec.go
@@ -19,6 +19,8 @@
 	"io"
 	"os/exec"
 	"strings"
+	"syscall"
+	"time"
 )
 
 // Cmd is a wrapper of os/exec.Cmd that integrates with the build context for
@@ -33,6 +35,8 @@
 	ctx    Context
 	config Config
 	name   string
+
+	started time.Time
 }
 
 func Command(ctx Context, config Config, name string, executable string, args ...string) *Cmd {
@@ -57,7 +61,20 @@
 		c.wrapSandbox()
 	}
 
-	c.ctx.Verboseln(c.Path, c.Args)
+	c.ctx.Verbosef("%q executing %q %v\n", c.name, c.Path, c.Args)
+	c.started = time.Now()
+}
+
+func (c *Cmd) report() {
+	if c.Cmd.ProcessState != nil {
+		rusage := c.Cmd.ProcessState.SysUsage().(*syscall.Rusage)
+		c.ctx.Verbosef("%q finished with exit code %d (%s real, %s user, %s system, %dMB maxrss)",
+			c.name, c.Cmd.ProcessState.ExitCode(),
+			time.Since(c.started).Round(time.Millisecond),
+			c.Cmd.ProcessState.UserTime().Round(time.Millisecond),
+			c.Cmd.ProcessState.SystemTime().Round(time.Millisecond),
+			rusage.Maxrss/1024)
+	}
 }
 
 func (c *Cmd) Start() error {
@@ -68,21 +85,30 @@
 func (c *Cmd) Run() error {
 	c.prepare()
 	err := c.Cmd.Run()
+	c.report()
 	return err
 }
 
 func (c *Cmd) Output() ([]byte, error) {
 	c.prepare()
 	bytes, err := c.Cmd.Output()
+	c.report()
 	return bytes, err
 }
 
 func (c *Cmd) CombinedOutput() ([]byte, error) {
 	c.prepare()
 	bytes, err := c.Cmd.CombinedOutput()
+	c.report()
 	return bytes, err
 }
 
+func (c *Cmd) Wait() error {
+	err := c.Cmd.Wait()
+	c.report()
+	return err
+}
+
 // StartOrFatal is equivalent to Start, but handles the error with a call to ctx.Fatal
 func (c *Cmd) StartOrFatal() {
 	if err := c.Start(); err != nil {
diff --git a/ui/build/kati.go b/ui/build/kati.go
index 8796a4f..2eb7850 100644
--- a/ui/build/kati.go
+++ b/ui/build/kati.go
@@ -67,6 +67,7 @@
 		"--ninja_dir=" + config.OutDir(),
 		"--ninja_suffix=" + config.KatiSuffix() + extraSuffix,
 		"--no_ninja_prelude",
+		"--use_ninja_phony_output",
 		"--regen",
 		"--ignore_optional_include=" + filepath.Join(config.OutDir(), "%.P"),
 		"--detect_android_echo",
diff --git a/ui/build/ninja.go b/ui/build/ninja.go
index dfc3be1..1b13e5d 100644
--- a/ui/build/ninja.go
+++ b/ui/build/ninja.go
@@ -58,6 +58,7 @@
 	args = append(args, "-f", config.CombinedNinjaFile())
 
 	args = append(args,
+		"-o", "usesphonyoutputs=yes",
 		"-w", "dupbuild=err",
 		"-w", "missingdepfile=err")
 
diff --git a/ui/build/soong.go b/ui/build/soong.go
index 9b8d648..2fbf381 100644
--- a/ui/build/soong.go
+++ b/ui/build/soong.go
@@ -119,7 +119,11 @@
 		cmd := Command(ctx, config, "soong "+name,
 			config.PrebuiltBuildTool("ninja"),
 			"-d", "keepdepfile",
+			"-o", "usesphonyoutputs=yes",
+			"-o", "preremoveoutputs=yes",
 			"-w", "dupbuild=err",
+			"-w", "outputdir=err",
+			"-w", "missingoutfile=err",
 			"-j", strconv.Itoa(config.Parallel()),
 			"--frontend_file", fifo,
 			"-f", filepath.Join(config.SoongOutDir(), file))
diff --git a/ui/build/test_build.go b/ui/build/test_build.go
index 5109465..4ff9483 100644
--- a/ui/build/test_build.go
+++ b/ui/build/test_build.go
@@ -50,10 +50,10 @@
 	// Get a list of leaf nodes in the dependency graph from ninja
 	executable := config.PrebuiltBuildTool("ninja")
 
-	args := []string{}
-	args = append(args, config.NinjaArgs()...)
-	args = append(args, "-f", config.CombinedNinjaFile())
-	args = append(args, "-t", "targets", "rule")
+	common_args := []string{}
+	common_args = append(common_args, config.NinjaArgs()...)
+	common_args = append(common_args, "-f", config.CombinedNinjaFile())
+	args := append(common_args, "-t", "targets", "rule")
 
 	cmd := Command(ctx, config, "ninja", executable, args...)
 	stdout, err := cmd.StdoutPipe()
@@ -96,9 +96,31 @@
 		sb := &strings.Builder{}
 		title := "Dependencies in out found with no rule to create them:"
 		fmt.Fprintln(sb, title)
-		for _, dep := range danglingRulesList {
-			fmt.Fprintln(sb, "  ", dep)
+
+		report_lines := 1
+		for i, dep := range danglingRulesList {
+			if report_lines > 20 {
+				fmt.Fprintf(sb, "  ... and %d more\n", len(danglingRulesList)-i)
+				break
+			}
+			// It's helpful to see the reverse dependencies. ninja -t query is the
+			// best tool we got for that. Its output starts with the dependency
+			// itself.
+			query_cmd := Command(ctx, config, "ninja", executable,
+				append(common_args, "-t", "query", dep)...)
+			query_stdout, err := query_cmd.StdoutPipe()
+			if err != nil {
+				ctx.Fatal(err)
+			}
+			query_cmd.StartOrFatal()
+			scanner := bufio.NewScanner(query_stdout)
+			for scanner.Scan() {
+				report_lines++
+				fmt.Fprintln(sb, " ", scanner.Text())
+			}
+			query_cmd.WaitOrFatal()
 		}
+
 		ts.FinishAction(status.ActionResult{
 			Action: action,
 			Error:  fmt.Errorf(title),
diff --git a/ui/metrics/Android.bp b/ui/metrics/Android.bp
index 529639d..3596e10 100644
--- a/ui/metrics/Android.bp
+++ b/ui/metrics/Android.bp
@@ -17,6 +17,7 @@
     pkgPath: "android/soong/ui/metrics",
     deps: [
         "golang-protobuf-proto",
+        "soong-ui-metrics_upload_proto",
         "soong-ui-metrics_proto",
         "soong-ui-tracer",
     ],
@@ -35,3 +36,11 @@
     ],
 }
 
+bootstrap_go_package {
+    name: "soong-ui-metrics_upload_proto",
+    pkgPath: "android/soong/ui/metrics/upload_proto",
+    deps: ["golang-protobuf-proto"],
+    srcs: [
+        "upload_proto/upload.pb.go",
+    ],
+}
diff --git a/ui/metrics/upload_proto/regen.sh b/ui/metrics/upload_proto/regen.sh
new file mode 100755
index 0000000..4521df7
--- /dev/null
+++ b/ui/metrics/upload_proto/regen.sh
@@ -0,0 +1,17 @@
+#!/bin/bash
+
+# Generates the golang source file of upload.proto file.
+
+set -e
+
+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:. upload.proto; then
+  die "build failed. ${error_msg}"
+fi
diff --git a/ui/metrics/upload_proto/upload.pb.go b/ui/metrics/upload_proto/upload.pb.go
new file mode 100644
index 0000000..1b1e5e8
--- /dev/null
+++ b/ui/metrics/upload_proto/upload.pb.go
@@ -0,0 +1,122 @@
+// Code generated by protoc-gen-go. DO NOT EDIT.
+// source: upload.proto
+
+package soong_metrics_upload_proto
+
+import (
+	fmt "fmt"
+	proto "github.com/golang/protobuf/proto"
+	math "math"
+)
+
+// Reference imports to suppress errors if they are not otherwise used.
+var _ = proto.Marshal
+var _ = fmt.Errorf
+var _ = math.Inf
+
+// This is a compile-time assertion to ensure that this generated file
+// is compatible with the proto package it is being compiled against.
+// A compilation error at this line likely means your copy of the
+// proto package needs to be updated.
+const _ = proto.ProtoPackageIsVersion3 // please upgrade the proto package
+
+type Upload struct {
+	// The timestamp in milliseconds that the build was created.
+	CreationTimestampMs *uint64 `protobuf:"varint,1,opt,name=creation_timestamp_ms,json=creationTimestampMs" json:"creation_timestamp_ms,omitempty"`
+	// The timestamp in milliseconds when the build was completed.
+	CompletionTimestampMs *uint64 `protobuf:"varint,2,opt,name=completion_timestamp_ms,json=completionTimestampMs" json:"completion_timestamp_ms,omitempty"`
+	// The branch name.
+	BranchName *string `protobuf:"bytes,3,opt,name=branch_name,json=branchName" json:"branch_name,omitempty"`
+	// The target name.
+	TargetName *string `protobuf:"bytes,4,opt,name=target_name,json=targetName" json:"target_name,omitempty"`
+	// A list of metrics filepaths to upload.
+	MetricsFiles         []string `protobuf:"bytes,5,rep,name=metrics_files,json=metricsFiles" json:"metrics_files,omitempty"`
+	XXX_NoUnkeyedLiteral struct{} `json:"-"`
+	XXX_unrecognized     []byte   `json:"-"`
+	XXX_sizecache        int32    `json:"-"`
+}
+
+func (m *Upload) Reset()         { *m = Upload{} }
+func (m *Upload) String() string { return proto.CompactTextString(m) }
+func (*Upload) ProtoMessage()    {}
+func (*Upload) Descriptor() ([]byte, []int) {
+	return fileDescriptor_91b94b655bd2a7e5, []int{0}
+}
+
+func (m *Upload) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_Upload.Unmarshal(m, b)
+}
+func (m *Upload) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_Upload.Marshal(b, m, deterministic)
+}
+func (m *Upload) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_Upload.Merge(m, src)
+}
+func (m *Upload) XXX_Size() int {
+	return xxx_messageInfo_Upload.Size(m)
+}
+func (m *Upload) XXX_DiscardUnknown() {
+	xxx_messageInfo_Upload.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_Upload proto.InternalMessageInfo
+
+func (m *Upload) GetCreationTimestampMs() uint64 {
+	if m != nil && m.CreationTimestampMs != nil {
+		return *m.CreationTimestampMs
+	}
+	return 0
+}
+
+func (m *Upload) GetCompletionTimestampMs() uint64 {
+	if m != nil && m.CompletionTimestampMs != nil {
+		return *m.CompletionTimestampMs
+	}
+	return 0
+}
+
+func (m *Upload) GetBranchName() string {
+	if m != nil && m.BranchName != nil {
+		return *m.BranchName
+	}
+	return ""
+}
+
+func (m *Upload) GetTargetName() string {
+	if m != nil && m.TargetName != nil {
+		return *m.TargetName
+	}
+	return ""
+}
+
+func (m *Upload) GetMetricsFiles() []string {
+	if m != nil {
+		return m.MetricsFiles
+	}
+	return nil
+}
+
+func init() {
+	proto.RegisterType((*Upload)(nil), "soong_metrics_upload.Upload")
+}
+
+func init() {
+	proto.RegisterFile("upload.proto", fileDescriptor_91b94b655bd2a7e5)
+}
+
+var fileDescriptor_91b94b655bd2a7e5 = []byte{
+	// 201 bytes of a gzipped FileDescriptorProto
+	0x1f, 0x8b, 0x08, 0x00, 0x00, 0x00, 0x00, 0x00, 0x02, 0xff, 0xe2, 0xe2, 0x29, 0x2d, 0xc8, 0xc9,
+	0x4f, 0x4c, 0xd1, 0x2b, 0x28, 0xca, 0x2f, 0xc9, 0x17, 0x12, 0x29, 0xce, 0xcf, 0xcf, 0x4b, 0x8f,
+	0xcf, 0x4d, 0x2d, 0x29, 0xca, 0x4c, 0x2e, 0x8e, 0x87, 0xc8, 0x29, 0xdd, 0x66, 0xe4, 0x62, 0x0b,
+	0x05, 0x33, 0x85, 0x8c, 0xb8, 0x44, 0x93, 0x8b, 0x52, 0x13, 0x4b, 0x32, 0xf3, 0xf3, 0xe2, 0x4b,
+	0x32, 0x73, 0x53, 0x8b, 0x4b, 0x12, 0x73, 0x0b, 0xe2, 0x73, 0x8b, 0x25, 0x18, 0x15, 0x18, 0x35,
+	0x58, 0x82, 0x84, 0x61, 0x92, 0x21, 0x30, 0x39, 0xdf, 0x62, 0x21, 0x33, 0x2e, 0xf1, 0xe4, 0xfc,
+	0xdc, 0x82, 0x9c, 0x54, 0x4c, 0x5d, 0x4c, 0x60, 0x5d, 0xa2, 0x08, 0x69, 0x64, 0x7d, 0xf2, 0x5c,
+	0xdc, 0x49, 0x45, 0x89, 0x79, 0xc9, 0x19, 0xf1, 0x79, 0x89, 0xb9, 0xa9, 0x12, 0xcc, 0x0a, 0x8c,
+	0x1a, 0x9c, 0x41, 0x5c, 0x10, 0x21, 0xbf, 0xc4, 0xdc, 0x54, 0x90, 0x82, 0x92, 0xc4, 0xa2, 0xf4,
+	0xd4, 0x12, 0x88, 0x02, 0x16, 0x88, 0x02, 0x88, 0x10, 0x58, 0x81, 0x32, 0x17, 0x2f, 0xcc, 0x2b,
+	0x69, 0x99, 0x39, 0xa9, 0xc5, 0x12, 0xac, 0x0a, 0xcc, 0x1a, 0x9c, 0x41, 0x3c, 0x50, 0x41, 0x37,
+	0x90, 0x98, 0x93, 0x4c, 0x94, 0x14, 0x36, 0x5f, 0xc7, 0x83, 0x43, 0x04, 0x10, 0x00, 0x00, 0xff,
+	0xff, 0xe2, 0x01, 0x74, 0x65, 0x20, 0x01, 0x00, 0x00,
+}
diff --git a/ui/metrics/upload_proto/upload.proto b/ui/metrics/upload_proto/upload.proto
new file mode 100644
index 0000000..7a9f080
--- /dev/null
+++ b/ui/metrics/upload_proto/upload.proto
@@ -0,0 +1,35 @@
+// Copyright 2020 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 = "proto2";
+
+package soong_metrics_upload;
+option go_package = "soong_metrics_upload_proto";
+
+message Upload {
+  // The timestamp in milliseconds that the build was created.
+  optional uint64 creation_timestamp_ms = 1;
+
+  // The timestamp in milliseconds when the build was completed.
+  optional uint64 completion_timestamp_ms = 2;
+
+  // The branch name.
+  optional string branch_name = 3;
+
+  // The target name.
+  optional string target_name = 4;
+
+  // A list of metrics filepaths to upload.
+  repeated string metrics_files = 5;
+}