diff --git a/android/expand.go b/android/expand.go
index 527c4ac6d..67fb4ee6e 100644
--- a/android/expand.go
+++ b/android/expand.go
@@ -18,12 +18,30 @@ import (
 	"fmt"
 	"strings"
 	"unicode"
+
+	"github.com/google/blueprint/proptools"
 )
 
+// ExpandNinjaEscaped substitutes $() variables in a string
+// $(var) is passed to mapping(var), which should return the expanded value, a bool for whether the result should
+// be left unescaped when using in a ninja value (generally false, true if the expanded value is a ninja variable like
+// '${in}'), and an error.
+// $$ is converted to $, which is escaped back to $$.
+func ExpandNinjaEscaped(s string, mapping func(string) (string, bool, error)) (string, error) {
+	return expand(s, true, mapping)
+}
+
 // Expand substitutes $() variables in a string
-// $(var) is passed to Expander(var)
-// $$ is converted to $
+// $(var) is passed to mapping(var), which should return the expanded value and an error.
+// $$ is converted to $.
 func Expand(s string, mapping func(string) (string, error)) (string, error) {
+	return expand(s, false, func(s string) (string, bool, error) {
+		s, err := mapping(s)
+		return s, false, err
+	})
+}
+
+func expand(s string, ninjaEscape bool, mapping func(string) (string, bool, error)) (string, error) {
 	// based on os.Expand
 	buf := make([]byte, 0, 2*len(s))
 	i := 0
@@ -33,10 +51,13 @@ func Expand(s string, mapping func(string) (string, error)) (string, error) {
 				return "", fmt.Errorf("expected character after '$'")
 			}
 			buf = append(buf, s[i:j]...)
-			value, w, err := getMapping(s[j+1:], mapping)
+			value, ninjaVariable, w, err := getMapping(s[j+1:], mapping)
 			if err != nil {
 				return "", err
 			}
+			if !ninjaVariable && ninjaEscape {
+				value = proptools.NinjaEscape(value)
+			}
 			buf = append(buf, value...)
 			j += w
 			i = j + 1
@@ -45,26 +66,26 @@ func Expand(s string, mapping func(string) (string, error)) (string, error) {
 	return string(buf) + s[i:], nil
 }
 
-func getMapping(s string, mapping func(string) (string, error)) (string, int, error) {
+func getMapping(s string, mapping func(string) (string, bool, error)) (string, bool, int, error) {
 	switch s[0] {
 	case '(':
 		// Scan to closing brace
 		for i := 1; i < len(s); i++ {
 			if s[i] == ')' {
-				ret, err := mapping(strings.TrimSpace(s[1:i]))
-				return ret, i + 1, err
+				ret, ninjaVariable, err := mapping(strings.TrimSpace(s[1:i]))
+				return ret, ninjaVariable, i + 1, err
 			}
 		}
-		return "", len(s), fmt.Errorf("missing )")
+		return "", false, len(s), fmt.Errorf("missing )")
 	case '$':
-		return "$$", 1, nil
+		return "$", false, 1, nil
 	default:
 		i := strings.IndexFunc(s, unicode.IsSpace)
 		if i == 0 {
-			return "", 0, fmt.Errorf("unexpected character '%c' after '$'", s[0])
+			return "", false, 0, fmt.Errorf("unexpected character '%c' after '$'", s[0])
 		} else if i == -1 {
 			i = len(s)
 		}
-		return "", 0, fmt.Errorf("expected '(' after '$', did you mean $(%s)?", s[:i])
+		return "", false, 0, fmt.Errorf("expected '(' after '$', did you mean $(%s)?", s[:i])
 	}
 }
diff --git a/android/expand_test.go b/android/expand_test.go
index 128de8a4e..12179eddf 100644
--- a/android/expand_test.go
+++ b/android/expand_test.go
@@ -20,88 +20,111 @@ import (
 )
 
 var vars = map[string]string{
-	"var1": "abc",
-	"var2": "",
-	"var3": "def",
-	"💩":    "😃",
+	"var1":   "abc",
+	"var2":   "",
+	"var3":   "def",
+	"💩":      "😃",
+	"escape": "${in}",
 }
 
-func expander(s string) (string, error) {
+func expander(s string) (string, bool, error) {
 	if val, ok := vars[s]; ok {
-		return val, nil
+		return val, s == "escape", nil
 	} else {
-		return "", fmt.Errorf("unknown variable %q", s)
+		return "", false, fmt.Errorf("unknown variable %q", s)
 	}
 }
 
 var expandTestCases = []struct {
-	in  string
-	out string
-	err bool
+	in          string
+	out         string
+	out_escaped string
+	err         bool
 }{
 	{
-		in:  "$(var1)",
-		out: "abc",
+		in:          "$(var1)",
+		out:         "abc",
+		out_escaped: "abc",
 	},
 	{
-		in:  "$( var1 )",
-		out: "abc",
+		in:          "$( var1 )",
+		out:         "abc",
+		out_escaped: "abc",
 	},
 	{
-		in:  "def$(var1)",
-		out: "defabc",
+		in:          "def$(var1)",
+		out:         "defabc",
+		out_escaped: "defabc",
 	},
 	{
-		in:  "$(var1)def",
-		out: "abcdef",
+		in:          "$(var1)def",
+		out:         "abcdef",
+		out_escaped: "abcdef",
 	},
 	{
-		in:  "def$(var1)def",
-		out: "defabcdef",
+		in:          "def$(var1)def",
+		out:         "defabcdef",
+		out_escaped: "defabcdef",
 	},
 	{
-		in:  "$(var2)",
-		out: "",
+		in:          "$(var2)",
+		out:         "",
+		out_escaped: "",
 	},
 	{
-		in:  "def$(var2)",
-		out: "def",
+		in:          "def$(var2)",
+		out:         "def",
+		out_escaped: "def",
 	},
 	{
-		in:  "$(var2)def",
-		out: "def",
+		in:          "$(var2)def",
+		out:         "def",
+		out_escaped: "def",
 	},
 	{
-		in:  "def$(var2)def",
-		out: "defdef",
+		in:          "def$(var2)def",
+		out:         "defdef",
+		out_escaped: "defdef",
 	},
 	{
-		in:  "$(var1)$(var3)",
-		out: "abcdef",
+		in:          "$(var1)$(var3)",
+		out:         "abcdef",
+		out_escaped: "abcdef",
 	},
 	{
-		in:  "$(var1)g$(var3)",
-		out: "abcgdef",
+		in:          "$(var1)g$(var3)",
+		out:         "abcgdef",
+		out_escaped: "abcgdef",
 	},
 	{
-		in:  "$$",
-		out: "$$",
+		in:          "$$",
+		out:         "$",
+		out_escaped: "$$",
 	},
 	{
-		in:  "$$(var1)",
-		out: "$$(var1)",
+		in:          "$$(var1)",
+		out:         "$(var1)",
+		out_escaped: "$$(var1)",
 	},
 	{
-		in:  "$$$(var1)",
-		out: "$$abc",
+		in:          "$$$(var1)",
+		out:         "$abc",
+		out_escaped: "$$abc",
 	},
 	{
-		in:  "$(var1)$$",
-		out: "abc$$",
+		in:          "$(var1)$$",
+		out:         "abc$",
+		out_escaped: "abc$$",
 	},
 	{
-		in:  "$(💩)",
-		out: "😃",
+		in:          "$(💩)",
+		out:         "😃",
+		out_escaped: "😃",
+	},
+	{
+		in:          "$$a$(escape)$$b",
+		out:         "$a${in}$b",
+		out_escaped: "$$a${in}$$b",
 	},
 
 	// Errors
@@ -141,7 +164,10 @@ var expandTestCases = []struct {
 
 func TestExpand(t *testing.T) {
 	for _, test := range expandTestCases {
-		got, err := Expand(test.in, expander)
+		got, err := Expand(test.in, func(s string) (string, error) {
+			s, _, err := expander(s)
+			return s, err
+		})
 		if err != nil && !test.err {
 			t.Errorf("%q: unexpected error %s", test.in, err.Error())
 		} else if err == nil && test.err {
@@ -151,3 +177,16 @@ func TestExpand(t *testing.T) {
 		}
 	}
 }
+
+func TestExpandNinjaEscaped(t *testing.T) {
+	for _, test := range expandTestCases {
+		got, err := ExpandNinjaEscaped(test.in, expander)
+		if err != nil && !test.err {
+			t.Errorf("%q: unexpected error %s", test.in, err.Error())
+		} else if err == nil && test.err {
+			t.Errorf("%q: expected error, got %q", test.in, got)
+		} else if !test.err && got != test.out_escaped {
+			t.Errorf("%q: expected %q, got %q", test.in, test.out, got)
+		}
+	}
+}
diff --git a/android/proto.go b/android/proto.go
index 5247c68dc..c8ade4564 100644
--- a/android/proto.go
+++ b/android/proto.go
@@ -135,7 +135,7 @@ func ProtoRule(ctx ModuleContext, rule *RuleBuilder, protoFile Path, flags Proto
 	}
 
 	rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "aprotoc")).
+		BuiltTool(ctx, "aprotoc").
 		FlagWithArg(flags.OutTypeFlag+"=", strings.Join(flags.OutParams, ",")+":"+outDir.String()).
 		FlagWithDepFile("--dependency_out=", depFile).
 		FlagWithArg("-I ", protoBase).
@@ -145,5 +145,5 @@ func ProtoRule(ctx ModuleContext, rule *RuleBuilder, protoFile Path, flags Proto
 		ImplicitOutputs(outputs)
 
 	rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "dep_fixer")).Flag(depFile.String())
+		BuiltTool(ctx, "dep_fixer").Flag(depFile.String())
 }
diff --git a/android/rule_builder.go b/android/rule_builder.go
index e53eb0d2a..1238ddc6d 100644
--- a/android/rule_builder.go
+++ b/android/rule_builder.go
@@ -263,11 +263,36 @@ func (r *RuleBuilder) Tools() Paths {
 	return toolsList
 }
 
-// Commands returns a slice containing a the built command line for each call to RuleBuilder.Command.
+// RspFileInputs returns the list of paths that were passed to the RuleBuilderCommand.FlagWithRspFileInputList method.
+func (r *RuleBuilder) RspFileInputs() Paths {
+	var rspFileInputs Paths
+	for _, c := range r.commands {
+		if c.rspFileInputs != nil {
+			if rspFileInputs != nil {
+				panic("Multiple commands in a rule may not have rsp file inputs")
+			}
+			rspFileInputs = c.rspFileInputs
+		}
+	}
+
+	return rspFileInputs
+}
+
+// Commands returns a slice containing the built command line for each call to RuleBuilder.Command.
 func (r *RuleBuilder) Commands() []string {
 	var commands []string
 	for _, c := range r.commands {
-		commands = append(commands, c.buf.String())
+		commands = append(commands, c.String())
+	}
+	return commands
+}
+
+// NinjaEscapedCommands returns a slice containin the built command line after ninja escaping for each call to
+// RuleBuilder.Command.
+func (r *RuleBuilder) NinjaEscapedCommands() []string {
+	var commands []string
+	for _, c := range r.commands {
+		commands = append(commands, c.NinjaEscapedString())
 	}
 	return commands
 }
@@ -284,7 +309,7 @@ var _ BuilderContext = SingletonContext(nil)
 
 func (r *RuleBuilder) depFileMergerCmd(ctx PathContext, depFiles WritablePaths) *RuleBuilderCommand {
 	return r.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "dep_fixer")).
+		BuiltTool(ctx, "dep_fixer").
 		Inputs(depFiles.Paths())
 }
 
@@ -324,7 +349,7 @@ func (r *RuleBuilder) Build(pctx PackageContext, ctx BuilderContext, name string
 	}
 
 	tools := r.Tools()
-	commands := r.Commands()
+	commands := r.NinjaEscapedCommands()
 	outputs := r.Outputs()
 
 	if len(commands) == 0 {
@@ -334,7 +359,7 @@ func (r *RuleBuilder) Build(pctx PackageContext, ctx BuilderContext, name string
 		panic("No outputs specified from any Commands")
 	}
 
-	commandString := strings.Join(proptools.NinjaEscapeList(commands), " && ")
+	commandString := strings.Join(commands, " && ")
 
 	if r.sbox {
 		sboxOutputs := make([]string, len(outputs))
@@ -352,7 +377,7 @@ func (r *RuleBuilder) Build(pctx PackageContext, ctx BuilderContext, name string
 		}
 
 		sboxCmd := &RuleBuilderCommand{}
-		sboxCmd.Tool(ctx.Config().HostToolPath(ctx, "sbox")).
+		sboxCmd.BuiltTool(ctx, "sbox").
 			Flag("-c").Text(commandString).
 			Flag("--sandbox-path").Text(shared.TempDirForOutDir(PathForOutput(ctx).String())).
 			Flag("--output-root").Text(r.sboxOutDir.String()).
@@ -363,17 +388,27 @@ func (r *RuleBuilder) Build(pctx PackageContext, ctx BuilderContext, name string
 	}
 
 	// Ninja doesn't like multiple outputs when depfiles are enabled, move all but the first output to
-	// ImplicitOutputs.  RuleBuilder never uses "$out", so the distinction between Outputs and ImplicitOutputs
-	// doesn't matter.
+	// ImplicitOutputs.  RuleBuilder only uses "$out" for the rsp file location, so the distinction between Outputs and
+	// ImplicitOutputs doesn't matter.
 	output := outputs[0]
 	implicitOutputs := outputs[1:]
 
+	var rspFile, rspFileContent string
+	rspFileInputs := r.RspFileInputs()
+	if rspFileInputs != nil {
+		rspFile = "$out.rsp"
+		rspFileContent = "$in"
+	}
+
 	ctx.Build(pctx, BuildParams{
 		Rule: ctx.Rule(pctx, name, blueprint.RuleParams{
-			Command:     commandString,
-			CommandDeps: tools.Strings(),
-			Restat:      r.restat,
+			Command:        commandString,
+			CommandDeps:    tools.Strings(),
+			Restat:         r.restat,
+			Rspfile:        rspFile,
+			RspfileContent: rspFileContent,
 		}),
+		Inputs:          rspFileInputs,
 		Implicits:       r.Inputs(),
 		Output:          output,
 		ImplicitOutputs: implicitOutputs,
@@ -388,11 +423,15 @@ func (r *RuleBuilder) Build(pctx PackageContext, ctx BuilderContext, name string
 // RuleBuilderCommand, so they can be used chained or unchained.  All methods that add text implicitly add a single
 // space as a separator from the previous method.
 type RuleBuilderCommand struct {
-	buf      strings.Builder
-	inputs   Paths
-	outputs  WritablePaths
-	depFiles WritablePaths
-	tools    Paths
+	buf           strings.Builder
+	inputs        Paths
+	outputs       WritablePaths
+	depFiles      WritablePaths
+	tools         Paths
+	rspFileInputs Paths
+
+	// spans [start,end) of the command that should not be ninja escaped
+	unescapedSpans [][2]int
 
 	sbox       bool
 	sboxOutDir WritablePath
@@ -478,6 +517,24 @@ func (c *RuleBuilderCommand) Tool(path Path) *RuleBuilderCommand {
 	return c.Text(path.String())
 }
 
+// BuiltTool adds the specified tool path that was built using a host Soong module to the command line.  The path will
+// be also added to the dependencies returned by RuleBuilder.Tools.
+//
+// It is equivalent to:
+//  cmd.Tool(ctx.Config().HostToolPath(ctx, tool))
+func (c *RuleBuilderCommand) BuiltTool(ctx PathContext, tool string) *RuleBuilderCommand {
+	return c.Tool(ctx.Config().HostToolPath(ctx, tool))
+}
+
+// PrebuiltBuildTool adds the specified tool path from prebuils/build-tools.  The path will be also added to the
+// dependencies returned by RuleBuilder.Tools.
+//
+// It is equivalent to:
+//  cmd.Tool(ctx.Config().PrebuiltBuildTool(ctx, tool))
+func (c *RuleBuilderCommand) PrebuiltBuildTool(ctx PathContext, tool string) *RuleBuilderCommand {
+	return c.Tool(ctx.Config().PrebuiltBuildTool(ctx, tool))
+}
+
 // Input adds the specified input path to the command line.  The path will also be added to the dependencies returned by
 // RuleBuilder.Inputs.
 func (c *RuleBuilderCommand) Input(path Path) *RuleBuilderCommand {
@@ -606,11 +663,56 @@ func (c *RuleBuilderCommand) FlagWithDepFile(flag string, path WritablePath) *Ru
 	return c.Text(flag + c.outputStr(path))
 }
 
+// FlagWithRspFileInputList adds the specified flag and path to an rspfile to the command line, with no separator
+// between them.  The paths will be written to the rspfile.
+func (c *RuleBuilderCommand) FlagWithRspFileInputList(flag string, paths Paths) *RuleBuilderCommand {
+	if c.rspFileInputs != nil {
+		panic("FlagWithRspFileInputList cannot be called if rsp file inputs have already been provided")
+	}
+
+	// Use an empty slice if paths is nil, the non-nil slice is used as an indicator that the rsp file must be
+	// generated.
+	if paths == nil {
+		paths = Paths{}
+	}
+
+	c.rspFileInputs = paths
+
+	rspFile := "$out.rsp"
+	c.FlagWithArg(flag, rspFile)
+	c.unescapedSpans = append(c.unescapedSpans, [2]int{c.buf.Len() - len(rspFile), c.buf.Len()})
+	return c
+}
+
 // String returns the command line.
 func (c *RuleBuilderCommand) String() string {
 	return c.buf.String()
 }
 
+// String returns the command line.
+func (c *RuleBuilderCommand) NinjaEscapedString() string {
+	return ninjaEscapeExceptForSpans(c.String(), c.unescapedSpans)
+}
+
+func ninjaEscapeExceptForSpans(s string, spans [][2]int) string {
+	if len(spans) == 0 {
+		return proptools.NinjaEscape(s)
+	}
+
+	sb := strings.Builder{}
+	sb.Grow(len(s) * 11 / 10)
+
+	i := 0
+	for _, span := range spans {
+		sb.WriteString(proptools.NinjaEscape(s[i:span[0]]))
+		sb.WriteString(s[span[0]:span[1]])
+		i = span[1]
+	}
+	sb.WriteString(proptools.NinjaEscape(s[i:]))
+
+	return sb.String()
+}
+
 func ninjaNameEscape(s string) string {
 	b := []byte(s)
 	escaped := false
diff --git a/android/rule_builder_test.go b/android/rule_builder_test.go
index cfbc2abee..6eba4f127 100644
--- a/android/rule_builder_test.go
+++ b/android/rule_builder_test.go
@@ -38,6 +38,7 @@ func pathContext() PathContext {
 			"ls":      nil,
 			"turbine": nil,
 			"java":    nil,
+			"javac":   nil,
 		})
 }
 
@@ -235,6 +236,34 @@ func ExampleRuleBuilderCommand_FlagWithList() {
 	// ls --sort=time,size
 }
 
+func ExampleRuleBuilderCommand_FlagWithRspFileInputList() {
+	ctx := pathContext()
+	fmt.Println(NewRuleBuilder().Command().
+		Tool(PathForSource(ctx, "javac")).
+		FlagWithRspFileInputList("@", PathsForTesting("a.java", "b.java")).
+		NinjaEscapedString())
+	// Output:
+	// javac @$out.rsp
+}
+
+func ExampleRuleBuilderCommand_String() {
+	fmt.Println(NewRuleBuilder().Command().
+		Text("FOO=foo").
+		Text("echo $FOO").
+		String())
+	// Output:
+	// FOO=foo echo $FOO
+}
+
+func ExampleRuleBuilderCommand_NinjaEscapedString() {
+	fmt.Println(NewRuleBuilder().Command().
+		Text("FOO=foo").
+		Text("echo $FOO").
+		NinjaEscapedString())
+	// Output:
+	// FOO=foo echo $$FOO
+}
+
 func TestRuleBuilder(t *testing.T) {
 	fs := map[string][]byte{
 		"dep_fixer": nil,
@@ -503,3 +532,77 @@ func TestRuleBuilder_Build(t *testing.T) {
 			"cp bar "+outFile, outFile, outFile+".d", true, nil)
 	})
 }
+
+func Test_ninjaEscapeExceptForSpans(t *testing.T) {
+	type args struct {
+		s     string
+		spans [][2]int
+	}
+	tests := []struct {
+		name string
+		args args
+		want string
+	}{
+		{
+			name: "empty",
+			args: args{
+				s: "",
+			},
+			want: "",
+		},
+		{
+			name: "unescape none",
+			args: args{
+				s: "$abc",
+			},
+			want: "$$abc",
+		},
+		{
+			name: "unescape all",
+			args: args{
+				s:     "$abc",
+				spans: [][2]int{{0, 4}},
+			},
+			want: "$abc",
+		},
+		{
+			name: "unescape first",
+			args: args{
+				s:     "$abc$",
+				spans: [][2]int{{0, 1}},
+			},
+			want: "$abc$$",
+		},
+		{
+			name: "unescape last",
+			args: args{
+				s:     "$abc$",
+				spans: [][2]int{{4, 5}},
+			},
+			want: "$$abc$",
+		},
+		{
+			name: "unescape middle",
+			args: args{
+				s:     "$a$b$c$",
+				spans: [][2]int{{2, 5}},
+			},
+			want: "$$a$b$c$$",
+		},
+		{
+			name: "unescape multiple",
+			args: args{
+				s:     "$a$b$c$",
+				spans: [][2]int{{2, 3}, {4, 5}},
+			},
+			want: "$$a$b$c$$",
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := ninjaEscapeExceptForSpans(tt.args.s, tt.args.spans); got != tt.want {
+				t.Errorf("ninjaEscapeExceptForSpans() = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}
diff --git a/cc/gen.go b/cc/gen.go
index 7516b2877..e5c41945e 100644
--- a/cc/gen.go
+++ b/cc/gen.go
@@ -99,7 +99,7 @@ func genYacc(ctx android.ModuleContext, rule *android.RuleBuilder, yaccFile andr
 
 	cmd.Text("BISON_PKGDATADIR=prebuilts/build-tools/common/bison").
 		FlagWithInput("M4=", ctx.Config().PrebuiltBuildTool(ctx, "m4")).
-		Tool(ctx.Config().PrebuiltBuildTool(ctx, "bison")).
+		PrebuiltBuildTool(ctx, "bison").
 		Flag("-d").
 		Flags(flags).
 		FlagWithOutput("--defines=", headerFile).
@@ -121,7 +121,7 @@ func genAidl(ctx android.ModuleContext, rule *android.RuleBuilder, aidlFile andr
 	headerBp := outDir.Join(ctx, aidlPackage, "Bp"+shortName+".h")
 
 	cmd := rule.Command()
-	cmd.Tool(ctx.Config().HostToolPath(ctx, "aidl-cpp")).
+	cmd.BuiltTool(ctx, "aidl-cpp").
 		FlagWithDepFile("-d", depFile).
 		Flag("--ninja").
 		Flag(aidlFlags).
diff --git a/cc/linker.go b/cc/linker.go
index dda2fcb33..fa3b0a63d 100644
--- a/cc/linker.go
+++ b/cc/linker.go
@@ -483,7 +483,7 @@ func (linker *baseLinker) injectVersionSymbol(ctx ModuleContext, in android.Path
 		Input:       in,
 		Output:      out,
 		Args: map[string]string{
-			"buildNumberFromFile": ctx.Config().BuildNumberFromFile(),
+			"buildNumberFromFile": proptools.NinjaEscape(ctx.Config().BuildNumberFromFile()),
 		},
 	})
 }
diff --git a/genrule/genrule.go b/genrule/genrule.go
index b0657ff14..411da0522 100644
--- a/genrule/genrule.go
+++ b/genrule/genrule.go
@@ -284,12 +284,12 @@ func (g *Module) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 
 	referencedDepfile := false
 
-	rawCommand, err := android.Expand(task.cmd, func(name string) (string, error) {
+	rawCommand, err := android.ExpandNinjaEscaped(task.cmd, func(name string) (string, bool, error) {
 		// report the error directly without returning an error to android.Expand to catch multiple errors in a
 		// single run
-		reportError := func(fmt string, args ...interface{}) (string, error) {
+		reportError := func(fmt string, args ...interface{}) (string, bool, error) {
 			ctx.PropertyErrorf("cmd", fmt, args...)
-			return "SOONG_ERROR", nil
+			return "SOONG_ERROR", false, nil
 		}
 
 		switch name {
@@ -304,19 +304,19 @@ func (g *Module) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 				return reportError("default label %q has multiple files, use $(locations %s) to reference it",
 					firstLabel, firstLabel)
 			}
-			return locationLabels[firstLabel][0], nil
+			return locationLabels[firstLabel][0], false, nil
 		case "in":
-			return "${in}", nil
+			return "${in}", true, nil
 		case "out":
-			return "__SBOX_OUT_FILES__", nil
+			return "__SBOX_OUT_FILES__", false, nil
 		case "depfile":
 			referencedDepfile = true
 			if !Bool(g.properties.Depfile) {
 				return reportError("$(depfile) used without depfile property")
 			}
-			return "__SBOX_DEPFILE__", nil
+			return "__SBOX_DEPFILE__", false, nil
 		case "genDir":
-			return "__SBOX_OUT_DIR__", nil
+			return "__SBOX_OUT_DIR__", false, nil
 		default:
 			if strings.HasPrefix(name, "location ") {
 				label := strings.TrimSpace(strings.TrimPrefix(name, "location "))
@@ -327,7 +327,7 @@ func (g *Module) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 						return reportError("label %q has multiple files, use $(locations %s) to reference it",
 							label, label)
 					}
-					return paths[0], nil
+					return paths[0], false, nil
 				} else {
 					return reportError("unknown location label %q", label)
 				}
@@ -337,7 +337,7 @@ func (g *Module) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 					if len(paths) == 0 {
 						return reportError("label %q has no files", label)
 					}
-					return strings.Join(paths, " "), nil
+					return strings.Join(paths, " "), false, nil
 				} else {
 					return reportError("unknown locations label %q", label)
 				}
diff --git a/java/app.go b/java/app.go
index 344265851..a679e8823 100644
--- a/java/app.go
+++ b/java/app.go
@@ -816,7 +816,7 @@ func (a *AndroidAppImport) uncompressEmbeddedJniLibs(
 	rule := android.NewRuleBuilder()
 	rule.Command().
 		Textf(`if (zipinfo %s 'lib/*.so' 2>/dev/null | grep -v ' stor ' >/dev/null) ; then`, inputPath).
-		Tool(ctx.Config().HostToolPath(ctx, "zip2zip")).
+		BuiltTool(ctx, "zip2zip").
 		FlagWithInput("-i ", inputPath).
 		FlagWithOutput("-o ", outputPath).
 		FlagWithArg("-0 ", "'lib/**/*.so'").
@@ -843,7 +843,7 @@ func (a *AndroidAppImport) uncompressDex(
 	rule := android.NewRuleBuilder()
 	rule.Command().
 		Textf(`if (zipinfo %s '*.dex' 2>/dev/null | grep -v ' stor ' >/dev/null) ; then`, inputPath).
-		Tool(ctx.Config().HostToolPath(ctx, "zip2zip")).
+		BuiltTool(ctx, "zip2zip").
 		FlagWithInput("-i ", inputPath).
 		FlagWithOutput("-o ", outputPath).
 		FlagWithArg("-0 ", "'classes*.dex'").
@@ -1067,7 +1067,7 @@ func (u *usesLibrary) verifyUsesLibrariesManifest(ctx android.ModuleContext, man
 	outputFile := android.PathForModuleOut(ctx, "manifest_check", "AndroidManifest.xml")
 
 	rule := android.NewRuleBuilder()
-	cmd := rule.Command().Tool(ctx.Config().HostToolPath(ctx, "manifest_check")).
+	cmd := rule.Command().BuiltTool(ctx, "manifest_check").
 		Flag("--enforce-uses-libraries").
 		Input(manifest).
 		FlagWithOutput("-o ", outputFile)
diff --git a/java/dexpreopt_bootjars.go b/java/dexpreopt_bootjars.go
index fe468a9e0..4ef5bcf4b 100644
--- a/java/dexpreopt_bootjars.go
+++ b/java/dexpreopt_bootjars.go
@@ -229,7 +229,7 @@ func buildBootImage(ctx android.SingletonContext, config bootImageConfig) *bootI
 	if image.zip != nil {
 		rule := android.NewRuleBuilder()
 		rule.Command().
-			Tool(ctx.Config().HostToolPath(ctx, "soong_zip")).
+			BuiltTool(ctx, "soong_zip").
 			FlagWithOutput("-o ", image.zip).
 			FlagWithArg("-C ", image.dir.String()).
 			FlagWithInputList("-f ", allFiles, " -f ")
@@ -438,7 +438,7 @@ func dumpOatRules(ctx android.SingletonContext, image *bootImage) {
 		rule := android.NewRuleBuilder()
 		rule.Command().
 			// TODO: for now, use the debug version for better error reporting
-			Tool(ctx.Config().HostToolPath(ctx, "oatdumpd")).
+			BuiltTool(ctx, "oatdumpd").
 			FlagWithInputList("--runtime-arg -Xbootclasspath:", image.dexPaths.Paths(), ":").
 			FlagWithList("--runtime-arg -Xbootclasspath-locations:", image.dexLocations, ":").
 			FlagWithArg("--image=", dexpreopt.PathToLocation(image.images[arch], arch)).Implicit(image.images[arch]).
diff --git a/java/droiddoc.go b/java/droiddoc.go
index 25101de81..ae810e11c 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -500,6 +500,7 @@ func (j *Javadoc) OutputFiles(tag string) (android.Paths, error) {
 	}
 }
 
+// javadoc converts .java source files to documentation using javadoc.
 func JavadocFactory() android.Module {
 	module := &Javadoc{}
 
@@ -509,6 +510,7 @@ func JavadocFactory() android.Module {
 	return module
 }
 
+// javadoc_host converts .java source files to documentation using javadoc.
 func JavadocHostFactory() android.Module {
 	module := &Javadoc{}
 
@@ -798,7 +800,7 @@ func (j *Javadoc) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 			"srcJarDir":         android.PathForModuleOut(ctx, "srcjars").String(),
 			"stubsDir":          android.PathForModuleOut(ctx, "stubsDir").String(),
 			"srcJars":           strings.Join(j.srcJars.Strings(), " "),
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"bootclasspathArgs": bootClasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
@@ -831,6 +833,7 @@ type Droiddoc struct {
 	apiFilePath android.Path
 }
 
+// droiddoc converts .java source files to documentation using doclava or dokka.
 func DroiddocFactory() android.Module {
 	module := &Droiddoc{}
 
@@ -841,6 +844,7 @@ func DroiddocFactory() android.Module {
 	return module
 }
 
+// droiddoc_host converts .java source files to documentation using doclava or dokka.
 func DroiddocHostFactory() android.Module {
 	module := &Droiddoc{}
 
@@ -918,7 +922,7 @@ func (d *Droiddoc) collectDoclavaDocsFlags(ctx android.ModuleContext, implicits
 	args := " -source 1.8 -J-Xmx1600m -J-XX:-OmitStackTraceInFastThrow -XDignore.symbol.file " +
 		"-doclet com.google.doclava.Doclava -docletpath " + jsilver.String() + ":" + doclava.String() + " " +
 		"-hdf page.build " + ctx.Config().BuildId() + "-" + ctx.Config().BuildNumberFromFile() + " " +
-		`-hdf page.now "$$(` + date + ` @$$(cat ` + ctx.Config().Getenv("BUILD_DATETIME_FILE") + `) "+%d %b %Y %k:%M")" `
+		`-hdf page.now "$(` + date + ` @$(cat ` + ctx.Config().Getenv("BUILD_DATETIME_FILE") + `) "+%d %b %Y %k:%M")" `
 
 	if String(d.properties.Custom_template) == "" {
 		// TODO: This is almost always droiddoc-templates-sdk
@@ -1095,7 +1099,7 @@ func (d *Droiddoc) transformDoclava(ctx android.ModuleContext, implicits android
 			"srcJarDir":         android.PathForModuleOut(ctx, "srcjars").String(),
 			"stubsDir":          android.PathForModuleOut(ctx, "stubsDir").String(),
 			"srcJars":           strings.Join(d.Javadoc.srcJars.Strings(), " "),
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
@@ -1117,7 +1121,7 @@ func (d *Droiddoc) transformCheckApi(ctx android.ModuleContext, apiFile, removed
 		Args: map[string]string{
 			"msg":                   msg,
 			"classpath":             checkApiClasspath.FormJavaClassPath(""),
-			"opts":                  opts,
+			"opts":                  proptools.NinjaEscape(opts),
 			"apiFile":               apiFile.String(),
 			"apiFileToCheck":        d.apiFile.String(),
 			"removedApiFile":        removedApiFile.String(),
@@ -1140,7 +1144,7 @@ func (d *Droiddoc) transformDokka(ctx android.ModuleContext, implicits android.P
 			"stubsDir":      android.PathForModuleOut(ctx, "dokka-stubsDir").String(),
 			"srcJars":       strings.Join(d.Javadoc.srcJars.Strings(), " "),
 			"classpathArgs": classpathArgs,
-			"opts":          opts,
+			"opts":          proptools.NinjaEscape(opts),
 			"docZip":        d.Javadoc.docZip.String(),
 		},
 	})
@@ -1258,6 +1262,9 @@ type Droidstubs struct {
 	jdiffStubsSrcJar android.WritablePath
 }
 
+// droidstubs passes sources files through Metalava to generate stub .java files that only contain the API to be
+// documented, filtering out hidden classes and methods.  The resulting .java files are intended to be passed to
+// a droiddoc module to generate documentation.
 func DroidstubsFactory() android.Module {
 	module := &Droidstubs{}
 
@@ -1268,6 +1275,10 @@ func DroidstubsFactory() android.Module {
 	return module
 }
 
+// droidstubs_host passes sources files through Metalava to generate stub .java files that only contain the API
+// to be documented, filtering out hidden classes and methods.  The resulting .java files are intended to be
+// passed to a droiddoc_host module to generate documentation.  Use a droidstubs_host instead of a droidstubs
+// module when symbols needed by the source files are provided by java_library_host modules.
 func DroidstubsHostFactory() android.Module {
 	module := &Droidstubs{}
 
@@ -1558,7 +1569,7 @@ func (d *Droidstubs) transformMetalava(ctx android.ModuleContext, implicits andr
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 		},
 	})
 }
@@ -1581,7 +1592,7 @@ func (d *Droidstubs) transformCheckApi(ctx android.ModuleContext,
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"msg":               msg,
 		},
 	})
@@ -1602,7 +1613,7 @@ func (d *Droidstubs) transformJdiff(ctx android.ModuleContext, implicits android
 			"srcJarDir":         android.PathForModuleOut(ctx, "jdiff-srcjars").String(),
 			"stubsDir":          android.PathForModuleOut(ctx, "jdiff-stubsDir").String(),
 			"srcJars":           strings.Join(d.Javadoc.srcJars.Strings(), " "),
-			"opts":              opts,
+			"opts":              proptools.NinjaEscape(opts),
 			"bootclasspathArgs": bootclasspathArgs,
 			"classpathArgs":     classpathArgs,
 			"sourcepathArgs":    sourcepathArgs,
@@ -1781,6 +1792,7 @@ type ExportedDroiddocDir struct {
 	dir  android.Path
 }
 
+// droiddoc_exported_dir exports a directory of html templates or nullability annotations for use by doclava.
 func ExportedDroiddocDirFactory() android.Module {
 	module := &ExportedDroiddocDir{}
 	module.AddProperties(&module.properties)
diff --git a/java/java.go b/java/java.go
index f9ec27e24..a49aad775 100644
--- a/java/java.go
+++ b/java/java.go
@@ -2088,14 +2088,14 @@ func (j *DexImport) GenerateAndroidBuildActions(ctx android.ModuleContext) {
 
 		// use zip2zip to uncompress classes*.dex files
 		rule.Command().
-			Tool(ctx.Config().HostToolPath(ctx, "zip2zip")).
+			BuiltTool(ctx, "zip2zip").
 			FlagWithInput("-i ", inputJar).
 			FlagWithOutput("-o ", temporary).
 			FlagWithArg("-0 ", "'classes*.dex'")
 
 		// use zipalign to align uncompressed classes*.dex files
 		rule.Command().
-			Tool(ctx.Config().HostToolPath(ctx, "zipalign")).
+			BuiltTool(ctx, "zipalign").
 			Flag("-f").
 			Text("4").
 			Input(temporary).
diff --git a/java/proto.go b/java/proto.go
index 37de1d283..0ec64997e 100644
--- a/java/proto.go
+++ b/java/proto.go
@@ -34,7 +34,7 @@ func genProto(ctx android.ModuleContext, protoFile android.Path, flags android.P
 	// Proto generated java files have an unknown package name in the path, so package the entire output directory
 	// into a srcjar.
 	rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "soong_zip")).
+		BuiltTool(ctx, "soong_zip").
 		Flag("-jar").
 		FlagWithOutput("-o ", srcJarFile).
 		FlagWithArg("-C ", outDir.String()).
diff --git a/java/sdk.go b/java/sdk.go
index 7b79a49f2..d1e2ae4d1 100644
--- a/java/sdk.go
+++ b/java/sdk.go
@@ -296,7 +296,7 @@ func createSdkFrameworkAidl(ctx android.SingletonContext) {
 			rule.Command().
 				Text("rm -f").Output(aidl)
 			rule.Command().
-				Tool(ctx.Config().HostToolPath(ctx, "sdkparcelables")).
+				BuiltTool(ctx, "sdkparcelables").
 				Input(jar).
 				Output(aidl)
 
diff --git a/python/proto.go b/python/proto.go
index 85ed1a517..b71e047a5 100644
--- a/python/proto.go
+++ b/python/proto.go
@@ -34,7 +34,7 @@ func genProto(ctx android.ModuleContext, protoFile android.Path, flags android.P
 	// Proto generated python files have an unknown package name in the path, so package the entire output directory
 	// into a srcszip.
 	zipCmd := rule.Command().
-		Tool(ctx.Config().HostToolPath(ctx, "soong_zip")).
+		BuiltTool(ctx, "soong_zip").
 		FlagWithOutput("-o ", srcsZipFile)
 	if pkgPath != "" {
 		zipCmd.FlagWithArg("-P ", pkgPath)
diff --git a/scripts/jar-wrapper.sh b/scripts/jar-wrapper.sh
index 71c1d9067..b46804157 100644
--- a/scripts/jar-wrapper.sh
+++ b/scripts/jar-wrapper.sh
@@ -48,11 +48,11 @@ if [ ! -r "${jardir}/${jarfile}" ]; then
     exit 1
 fi
 
-javaOpts=""
+declare -a javaOpts=()
 while expr "x$1" : 'x-J' >/dev/null; do
-    opt=`expr "$1" : '-J\(.*\)'`
-    javaOpts="${javaOpts} -${opt}"
+    opt=`expr "$1" : '-J-\{0,1\}\(.*\)'`
+    javaOpts+=("-${opt}")
     shift
 done
 
-exec java ${javaOpts} -jar ${jardir}/${jarfile} "$@"
+exec java "${javaOpts[@]}" -jar ${jardir}/${jarfile} "$@"