diff --git a/src/internal/testenv/testenv.go b/src/internal/testenv/testenv.go
index 9e684e3034..f134f6b04a 100644
--- a/src/internal/testenv/testenv.go
+++ b/src/internal/testenv/testenv.go
@@ -16,6 +16,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strconv"
 	"strings"
 	"testing"
 )
@@ -133,3 +134,9 @@ func SkipFlaky(t *testing.T, issue int) {
 		t.Skipf("skipping known flaky test without the -flaky flag; see golang.org/issue/%d", issue)
 	}
 }
+
+func SkipFlakyNet(t *testing.T) {
+	if v, _ := strconv.ParseBool(os.Getenv("GO_BUILDER_FLAKY_NET")); v {
+		t.Skip("skipping test on builder known to have frequent network failures")
+	}
+}
diff --git a/src/net/lookup_test.go b/src/net/lookup_test.go
index 6e54fdba76..fb3cf18d3b 100644
--- a/src/net/lookup_test.go
+++ b/src/net/lookup_test.go
@@ -498,6 +498,7 @@ func TestLookupDotsWithRemoteSource(t *testing.T) {
 func testDots(t *testing.T, mode string) {
 	names, err := LookupAddr("8.8.8.8") // Google dns server
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupAddr(8.8.8.8): %v (mode=%v)", err, mode)
 	} else {
 		for _, name := range names {
@@ -509,12 +510,16 @@ func testDots(t *testing.T, mode string) {
 	}
 
 	cname, err := LookupCNAME("www.mit.edu")
-	if err != nil || !strings.HasSuffix(cname, ".") {
-		t.Errorf("LookupCNAME(www.mit.edu) = %v, %v, want cname ending in . with trailing dot (mode=%v)", cname, err, mode)
+	if err != nil {
+		testenv.SkipFlakyNet(t)
+		t.Errorf("LookupCNAME(www.mit.edu, mode=%v): %v", mode, err)
+	} else if !strings.HasSuffix(cname, ".") {
+		t.Errorf("LookupCNAME(www.mit.edu) = %v, want cname ending in . with trailing dot (mode=%v)", cname, mode)
 	}
 
 	mxs, err := LookupMX("google.com")
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupMX(google.com): %v (mode=%v)", err, mode)
 	} else {
 		for _, mx := range mxs {
@@ -527,6 +532,7 @@ func testDots(t *testing.T, mode string) {
 
 	nss, err := LookupNS("google.com")
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupNS(google.com): %v (mode=%v)", err, mode)
 	} else {
 		for _, ns := range nss {
@@ -539,6 +545,7 @@ func testDots(t *testing.T, mode string) {
 
 	cname, srvs, err := LookupSRV("xmpp-server", "tcp", "google.com")
 	if err != nil {
+		testenv.SkipFlakyNet(t)
 		t.Errorf("LookupSRV(xmpp-server, tcp, google.com): %v (mode=%v)", err, mode)
 	} else {
 		if !strings.HasSuffix(cname, ".google.com.") {