diff --git a/src/cmd/cgo/gcc.go b/src/cmd/cgo/gcc.go
index aa418af93b..1f18657400 100644
--- a/src/cmd/cgo/gcc.go
+++ b/src/cmd/cgo/gcc.go
@@ -183,16 +183,16 @@ func splitQuoted(s string) (r []string, err error) {
 	return args, err
 }
 
-// Translate rewrites f.AST, the original Go input, to remove
-// references to the imported package C, replacing them with
-// references to the equivalent Go types, functions, and variables.
-func (p *Package) Translate(f *File) {
+// loadDebug runs gcc to load debug information for the File. The debug
+// information will be saved to the debugs field of the file, and be
+// processed when Translate is called on the file later.
+// loadDebug is called concurrently with different files.
+func (f *File) loadDebug(p *Package) {
 	for _, cref := range f.Ref {
 		// Convert C.ulong to C.unsigned long, etc.
 		cref.Name.C = cname(cref.Name.Go)
 	}
 
-	var debugs []*debug // debug data from iterations of gccDebug
 	ft := fileTypedefs{typedefs: make(map[string]bool)}
 	numTypedefs := -1
 	for len(ft.typedefs) > numTypedefs {
@@ -211,7 +211,7 @@ func (p *Package) Translate(f *File) {
 		}
 		needType := p.guessKinds(f)
 		if len(needType) > 0 {
-			debugs = append(debugs, p.loadDWARF(f, &ft, needType))
+			f.debugs = append(f.debugs, p.loadDWARF(f, &ft, needType))
 		}
 
 		// In godefs mode we're OK with the typedefs, which
@@ -221,10 +221,16 @@ func (p *Package) Translate(f *File) {
 			break
 		}
 	}
+}
 
+// Translate rewrites f.AST, the original Go input, to remove
+// references to the imported package C, replacing them with
+// references to the equivalent Go types, functions, and variables.
+// Preconditions: File.loadDebug must be called prior to translate.
+func (p *Package) Translate(f *File) {
 	var conv typeConv
 	conv.Init(p.PtrSize, p.IntSize)
-	for _, d := range debugs {
+	for _, d := range f.debugs {
 		p.recordTypes(f, d, &conv)
 	}
 	p.prepareNames(f)
@@ -283,6 +289,7 @@ func (f *File) loadDefines(gccOptions []string) bool {
 // guessKinds tricks gcc into revealing the kind of each
 // name xxx for the references C.xxx in the Go input.
 // The kind is either a constant, type, or variable.
+// guessKinds is called concurrently with different files.
 func (p *Package) guessKinds(f *File) []*Name {
 	// Determine kinds for names we already know about,
 	// like #defines or 'struct foo', before bothering with gcc.
@@ -526,6 +533,7 @@ func (p *Package) guessKinds(f *File) []*Name {
 // loadDWARF parses the DWARF debug information generated
 // by gcc to learn the details of the constants, variables, and types
 // being referred to as C.xxx.
+// loadDwarf is called concurrently with different files.
 func (p *Package) loadDWARF(f *File, ft *fileTypedefs, names []*Name) *debug {
 	// Extract the types from the DWARF section of an object
 	// from a well-formed C program. Gcc only generates DWARF info
@@ -1789,6 +1797,7 @@ func gccTmp() string {
 
 // gccCmd returns the gcc command line to use for compiling
 // the input.
+// gccCommand is called concurrently for different files.
 func (p *Package) gccCmd(ofile string) []string {
 	c := append(gccBaseCmd,
 		"-w",         // no warnings
@@ -1832,6 +1841,7 @@ func (p *Package) gccCmd(ofile string) []string {
 
 // gccDebug runs gcc -gdwarf-2 over the C program stdin and
 // returns the corresponding DWARF data and, if present, debug data block.
+// gccDebug is called concurrently with different C programs.
 func (p *Package) gccDebug(stdin []byte, nnames int) (d *dwarf.Data, ints []int64, floats []float64, strs []string) {
 	ofile := gccTmp()
 	runGcc(stdin, p.gccCmd(ofile))
@@ -2222,6 +2232,7 @@ func gccDefines(stdin []byte, gccOptions []string) string {
 // gccErrors runs gcc over the C program stdin and returns
 // the errors that gcc prints. That is, this function expects
 // gcc to fail.
+// gccErrors is called concurrently with different C programs.
 func (p *Package) gccErrors(stdin []byte, extraArgs ...string) string {
 	// TODO(rsc): require failure
 	args := p.gccCmd(gccTmp())
diff --git a/src/cmd/cgo/main.go b/src/cmd/cgo/main.go
index df3b7fbd1d..5e08427daf 100644
--- a/src/cmd/cgo/main.go
+++ b/src/cmd/cgo/main.go
@@ -30,6 +30,7 @@ import (
 	"cmd/internal/edit"
 	"cmd/internal/hash"
 	"cmd/internal/objabi"
+	"cmd/internal/par"
 	"cmd/internal/telemetry/counter"
 )
 
@@ -74,6 +75,8 @@ type File struct {
 	NoCallbacks map[string]bool     // C function names that with #cgo nocallback directive
 	NoEscapes   map[string]bool     // C function names that with #cgo noescape directive
 	Edit        *edit.Buffer
+
+	debugs []*debug // debug data from iterations of gccDebug. Initialized by File.loadDebug.
 }
 
 func (f *File) offset(p token.Pos) int {
@@ -391,7 +394,7 @@ func main() {
 	h := hash.New32()
 	io.WriteString(h, *importPath)
 	var once sync.Once
-	var wg sync.WaitGroup
+	q := par.NewQueue(runtime.GOMAXPROCS(0))
 	fs := make([]*File, len(goFiles))
 	for i, input := range goFiles {
 		if *srcDir != "" {
@@ -413,9 +416,7 @@ func main() {
 			fatalf("%s", err)
 		}
 
-		wg.Add(1)
-		go func() {
-			defer wg.Done()
+		q.Add(func() {
 			// Apply trimpath to the file path. The path won't be read from after this point.
 			input, _ = objabi.ApplyRewrites(input, *trimpath)
 			if strings.ContainsAny(input, "\r\n") {
@@ -436,10 +437,12 @@ func main() {
 			})
 
 			fs[i] = f
-		}()
+
+			f.loadDebug(p)
+		})
 	}
 
-	wg.Wait()
+	<-q.Idle()
 
 	cPrefix = fmt.Sprintf("_%x", h.Sum(nil)[0:6])
 
diff --git a/src/cmd/dist/buildtool.go b/src/cmd/dist/buildtool.go
index b7e5891981..080de832b2 100644
--- a/src/cmd/dist/buildtool.go
+++ b/src/cmd/dist/buildtool.go
@@ -49,6 +49,7 @@ var bootstrapDirs = []string{
 	"cmd/internal/macho",
 	"cmd/internal/obj/...",
 	"cmd/internal/objabi",
+	"cmd/internal/par",
 	"cmd/internal/pgo",
 	"cmd/internal/pkgpath",
 	"cmd/internal/quoted",