diff --git a/go/loader/stdlib_test.go b/go/loader/stdlib_test.go
index 3eba7b29b0..7c09322b66 100644
--- a/go/loader/stdlib_test.go
+++ b/go/loader/stdlib_test.go
@@ -17,42 +17,17 @@ import (
 	"go/build"
 	"go/token"
 	"io/ioutil"
-	"os"
 	"path/filepath"
 	"runtime"
 	"strings"
 	"testing"
 	"time"
 
+	"code.google.com/p/go.tools/go/buildutil"
 	"code.google.com/p/go.tools/go/loader"
 	"code.google.com/p/go.tools/go/types"
 )
 
-func allPackages() []string {
-	var pkgs []string
-	root := filepath.Join(runtime.GOROOT(), "src") + string(os.PathSeparator)
-	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
-		// Prune the search if we encounter any of these names:
-		switch filepath.Base(path) {
-		case "testdata", ".hg":
-			return filepath.SkipDir
-		}
-		if info.IsDir() {
-			pkg := filepath.ToSlash(strings.TrimPrefix(path, root))
-			switch pkg {
-			case "builtin", "pkg":
-				return filepath.SkipDir // skip these subtrees
-			case "":
-				return nil // ignore root of tree
-			}
-			pkgs = append(pkgs, pkg)
-		}
-
-		return nil
-	})
-	return pkgs
-}
-
 func TestStdlib(t *testing.T) {
 	runtime.GC()
 	t0 := time.Now()
@@ -61,8 +36,10 @@ func TestStdlib(t *testing.T) {
 	alloc := memstats.Alloc
 
 	// Load, parse and type-check the program.
-	var conf loader.Config
-	for _, path := range allPackages() {
+	ctxt := build.Default // copy
+	ctxt.GOPATH = ""      // disable GOPATH
+	conf := loader.Config{Build: &ctxt}
+	for _, path := range buildutil.AllPackagesList(conf.Build) {
 		if err := conf.ImportWithTests(path); err != nil {
 			t.Error(err)
 		}
diff --git a/go/pointer/stdlib_test.go b/go/pointer/stdlib_test.go
index f6a2ab4879..d0fd4f6447 100644
--- a/go/pointer/stdlib_test.go
+++ b/go/pointer/stdlib_test.go
@@ -14,14 +14,12 @@ package pointer
 
 import (
 	"flag"
+	"go/build"
 	"go/token"
-	"os"
-	"path/filepath"
-	"runtime"
-	"strings"
 	"testing"
 	"time"
 
+	"code.google.com/p/go.tools/go/buildutil"
 	"code.google.com/p/go.tools/go/loader"
 	"code.google.com/p/go.tools/go/ssa"
 	"code.google.com/p/go.tools/go/ssa/ssautil"
@@ -29,42 +27,19 @@ import (
 
 var runStdlibTest = flag.Bool("stdlib", false, "Run the (slow) stdlib test")
 
-// TODO(adonovan): move this to go/buildutil package since we have four copies:
-// go/{loader,pointer,ssa}/stdlib_test.go and godoc/analysis/analysis.go.
-func allPackages() []string {
-	var pkgs []string
-	root := filepath.Join(runtime.GOROOT(), "src") + string(os.PathSeparator)
-	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
-		// Prune the search if we encounter any of these names:
-		switch filepath.Base(path) {
-		case "testdata", ".hg":
-			return filepath.SkipDir
-		}
-		if info.IsDir() {
-			pkg := filepath.ToSlash(strings.TrimPrefix(path, root))
-			switch pkg {
-			case "builtin", "pkg":
-				return filepath.SkipDir // skip these subtrees
-			case "":
-				return nil // ignore root of tree
-			}
-			pkgs = append(pkgs, pkg)
-		}
-
-		return nil
-	})
-	return pkgs
-}
-
 func TestStdlib(t *testing.T) {
 	if !*runStdlibTest {
 		t.Skip("skipping (slow) stdlib test (use --stdlib)")
 	}
 
 	// Load, parse and type-check the program.
-	var conf loader.Config
-	conf.SourceImports = true
-	if _, err := conf.FromArgs(allPackages(), true); err != nil {
+	ctxt := build.Default // copy
+	ctxt.GOPATH = ""      // disable GOPATH
+	conf := loader.Config{
+		SourceImports: true,
+		Build:         &ctxt,
+	}
+	if _, err := conf.FromArgs(buildutil.AllPackagesList(conf.Build), true); err != nil {
 		t.Errorf("FromArgs failed: %v", err)
 		return
 	}
diff --git a/go/ssa/stdlib_test.go b/go/ssa/stdlib_test.go
index 708c1ae6db..14a8b54e75 100644
--- a/go/ssa/stdlib_test.go
+++ b/go/ssa/stdlib_test.go
@@ -10,51 +10,30 @@ package ssa_test
 // Run test with GOMAXPROCS=8.
 
 import (
+	"go/build"
 	"go/token"
-	"os"
-	"path/filepath"
 	"runtime"
-	"strings"
 	"testing"
 	"time"
 
+	"code.google.com/p/go.tools/go/buildutil"
 	"code.google.com/p/go.tools/go/loader"
 	"code.google.com/p/go.tools/go/ssa"
 	"code.google.com/p/go.tools/go/ssa/ssautil"
 )
 
-func allPackages() []string {
-	var pkgs []string
-	root := filepath.Join(runtime.GOROOT(), "src") + string(os.PathSeparator)
-	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {
-		// Prune the search if we encounter any of these names:
-		switch filepath.Base(path) {
-		case "testdata", ".hg":
-			return filepath.SkipDir
-		}
-		if info.IsDir() {
-			pkg := filepath.ToSlash(strings.TrimPrefix(path, root))
-			switch pkg {
-			case "builtin", "pkg":
-				return filepath.SkipDir // skip these subtrees
-			case "":
-				return nil // ignore root of tree
-			}
-			pkgs = append(pkgs, pkg)
-		}
-
-		return nil
-	})
-	return pkgs
-}
-
 func TestStdlib(t *testing.T) {
 	// Load, parse and type-check the program.
 	t0 := time.Now()
 
-	var conf loader.Config
-	conf.SourceImports = true
-	if _, err := conf.FromArgs(allPackages(), true); err != nil {
+	// Load, parse and type-check the program.
+	ctxt := build.Default // copy
+	ctxt.GOPATH = ""      // disable GOPATH
+	conf := loader.Config{
+		SourceImports: true,
+		Build:         &ctxt,
+	}
+	if _, err := conf.FromArgs(buildutil.AllPackagesList(conf.Build), true); err != nil {
 		t.Errorf("FromArgs failed: %v", err)
 		return
 	}
diff --git a/godoc/analysis/analysis.go b/godoc/analysis/analysis.go
index f426f13f19..ae84bbcca7 100644
--- a/godoc/analysis/analysis.go
+++ b/godoc/analysis/analysis.go
@@ -575,6 +575,8 @@ func (a linksByStart) Len() int           { return len(a) }
 // specified package root directory, e.g. $GOROOT/src or $GOPATH/src.
 // Derived from from go/ssa/stdlib_test.go
 // root must end with os.PathSeparator.
+//
+// TODO(adonovan): use buildutil.AllPackages when the tree thaws.
 func allPackages(root string) []string {
 	var pkgs []string
 	filepath.Walk(root, func(path string, info os.FileInfo, err error) error {