diff --git a/src/net/ip_test.go b/src/net/ip_test.go
index f765582cad..ad13388dd2 100644
--- a/src/net/ip_test.go
+++ b/src/net/ip_test.go
@@ -469,61 +469,77 @@ func TestNetworkNumberAndMask(t *testing.T) {
 	}
 }
 
-var splitJoinTests = []struct {
-	host string
-	port string
-	join string
-}{
-	{"www.google.com", "80", "www.google.com:80"},
-	{"127.0.0.1", "1234", "127.0.0.1:1234"},
-	{"::1", "80", "[::1]:80"},
-	{"fe80::1%lo0", "80", "[fe80::1%lo0]:80"},
-	{"localhost%lo0", "80", "[localhost%lo0]:80"},
-	{"", "0", ":0"},
-
-	{"google.com", "https%foo", "google.com:https%foo"}, // Go 1.0 behavior
-	{"127.0.0.1", "", "127.0.0.1:"},                     // Go 1.0 behavior
-	{"www.google.com", "", "www.google.com:"},           // Go 1.0 behavior
-}
-
-var splitFailureTests = []struct {
-	hostPort string
-	err      string
-}{
-	{"www.google.com", "missing port in address"},
-	{"127.0.0.1", "missing port in address"},
-	{"[::1]", "missing port in address"},
-	{"[fe80::1%lo0]", "missing port in address"},
-	{"[localhost%lo0]", "missing port in address"},
-	{"localhost%lo0", "missing port in address"},
-
-	{"::1", "too many colons in address"},
-	{"fe80::1%lo0", "too many colons in address"},
-	{"fe80::1%lo0:80", "too many colons in address"},
-
-	{"localhost%lo0:80", "missing brackets in address"},
-
-	// Test cases that didn't fail in Go 1.0
-
-	{"[foo:bar]", "missing port in address"},
-	{"[foo:bar]baz", "missing port in address"},
-	{"[foo]bar:baz", "missing port in address"},
-
-	{"[foo]:[bar]:baz", "too many colons in address"},
-
-	{"[foo]:[bar]baz", "unexpected '[' in address"},
-	{"foo[bar]:baz", "unexpected '[' in address"},
-
-	{"foo]bar:baz", "unexpected ']' in address"},
-}
-
 func TestSplitHostPort(t *testing.T) {
-	for _, tt := range splitJoinTests {
-		if host, port, err := SplitHostPort(tt.join); host != tt.host || port != tt.port || err != nil {
-			t.Errorf("SplitHostPort(%q) = %q, %q, %v; want %q, %q, nil", tt.join, host, port, err, tt.host, tt.port)
+	for _, tt := range []struct {
+		hostPort string
+		host     string
+		port     string
+	}{
+		// Host name
+		{"localhost:http", "localhost", "http"},
+		{"localhost:80", "localhost", "80"},
+
+		// Go-specific host name with zone identifier
+		{"localhost%lo0:http", "localhost%lo0", "http"},
+		{"localhost%lo0:80", "localhost%lo0", "80"},
+		{"[localhost%lo0]:http", "localhost%lo0", "http"}, // Go 1 behavior
+		{"[localhost%lo0]:80", "localhost%lo0", "80"},     // Go 1 behavior
+
+		// IP literal
+		{"127.0.0.1:http", "127.0.0.1", "http"},
+		{"127.0.0.1:80", "127.0.0.1", "80"},
+		{"[::1]:http", "::1", "http"},
+		{"[::1]:80", "::1", "80"},
+
+		// IP literal with zone identifier
+		{"[::1%lo0]:http", "::1%lo0", "http"},
+		{"[::1%lo0]:80", "::1%lo0", "80"},
+
+		// Go-specific wildcard for host name
+		{":http", "", "http"}, // Go 1 behavior
+		{":80", "", "80"},     // Go 1 behavior
+
+		// Go-specific wildcard for service name or transport port number
+		{"golang.org:", "golang.org", ""}, // Go 1 behavior
+		{"127.0.0.1:", "127.0.0.1", ""},   // Go 1 behavior
+		{"[::1]:", "::1", ""},             // Go 1 behavior
+
+		// Opaque service name
+		{"golang.org:https%foo", "golang.org", "https%foo"}, // Go 1 behavior
+	} {
+		if host, port, err := SplitHostPort(tt.hostPort); host != tt.host || port != tt.port || err != nil {
+			t.Errorf("SplitHostPort(%q) = %q, %q, %v; want %q, %q, nil", tt.hostPort, host, port, err, tt.host, tt.port)
 		}
 	}
-	for _, tt := range splitFailureTests {
+
+	for _, tt := range []struct {
+		hostPort string
+		err      string
+	}{
+		{"golang.org", "missing port in address"},
+		{"127.0.0.1", "missing port in address"},
+		{"[::1]", "missing port in address"},
+		{"[fe80::1%lo0]", "missing port in address"},
+		{"[localhost%lo0]", "missing port in address"},
+		{"localhost%lo0", "missing port in address"},
+
+		{"::1", "too many colons in address"},
+		{"fe80::1%lo0", "too many colons in address"},
+		{"fe80::1%lo0:80", "too many colons in address"},
+
+		// Test cases that didn't fail in Go 1
+
+		{"[foo:bar]", "missing port in address"},
+		{"[foo:bar]baz", "missing port in address"},
+		{"[foo]bar:baz", "missing port in address"},
+
+		{"[foo]:[bar]:baz", "too many colons in address"},
+
+		{"[foo]:[bar]baz", "unexpected '[' in address"},
+		{"foo[bar]:baz", "unexpected '[' in address"},
+
+		{"foo]bar:baz", "unexpected ']' in address"},
+	} {
 		if host, port, err := SplitHostPort(tt.hostPort); err == nil {
 			t.Errorf("SplitHostPort(%q) should have failed", tt.hostPort)
 		} else {
@@ -539,9 +555,43 @@ func TestSplitHostPort(t *testing.T) {
 }
 
 func TestJoinHostPort(t *testing.T) {
-	for _, tt := range splitJoinTests {
-		if join := JoinHostPort(tt.host, tt.port); join != tt.join {
-			t.Errorf("JoinHostPort(%q, %q) = %q; want %q", tt.host, tt.port, join, tt.join)
+	for _, tt := range []struct {
+		host     string
+		port     string
+		hostPort string
+	}{
+		// Host name
+		{"localhost", "http", "localhost:http"},
+		{"localhost", "80", "localhost:80"},
+
+		// Go-specific host name with zone identifier
+		{"localhost%lo0", "http", "localhost%lo0:http"},
+		{"localhost%lo0", "80", "localhost%lo0:80"},
+
+		// IP literal
+		{"127.0.0.1", "http", "127.0.0.1:http"},
+		{"127.0.0.1", "80", "127.0.0.1:80"},
+		{"::1", "http", "[::1]:http"},
+		{"::1", "80", "[::1]:80"},
+
+		// IP literal with zone identifier
+		{"::1%lo0", "http", "[::1%lo0]:http"},
+		{"::1%lo0", "80", "[::1%lo0]:80"},
+
+		// Go-specific wildcard for host name
+		{"", "http", ":http"}, // Go 1 behavior
+		{"", "80", ":80"},     // Go 1 behavior
+
+		// Go-specific wildcard for service name or transport port number
+		{"golang.org", "", "golang.org:"}, // Go 1 behavior
+		{"127.0.0.1", "", "127.0.0.1:"},   // Go 1 behavior
+		{"::1", "", "[::1]:"},             // Go 1 behavior
+
+		// Opaque service name
+		{"golang.org", "https%foo", "golang.org:https%foo"}, // Go 1 behavior
+	} {
+		if hostPort := JoinHostPort(tt.host, tt.port); hostPort != tt.hostPort {
+			t.Errorf("JoinHostPort(%q, %q) = %q; want %q", tt.host, tt.port, hostPort, tt.hostPort)
 		}
 	}
 }
diff --git a/src/net/ipsock.go b/src/net/ipsock.go
index f1394a7ed8..9618c66440 100644
--- a/src/net/ipsock.go
+++ b/src/net/ipsock.go
@@ -107,10 +107,11 @@ func ipv6only(addr IPAddr) bool {
 }
 
 // SplitHostPort splits a network address of the form "host:port",
-// "[host]:port" or "[ipv6-host%zone]:port" into host or
-// ipv6-host%zone and port. A literal address or host name for IPv6
-// must be enclosed in square brackets, as in "[::1]:80",
-// "[ipv6-host]:http" or "[ipv6-host%zone]:80".
+// "host%zone:port", "[host]:port" or "[host%zone]:port" into host or
+// host%zone and port.
+//
+// A literal IPv6 address in hostport must be enclosed in square
+// brackets, as in "[::1]:80", "[::1%lo0]:80".
 func SplitHostPort(hostport string) (host, port string, err error) {
 	const (
 		missingPort   = "missing port in address"
@@ -154,9 +155,6 @@ func SplitHostPort(hostport string) (host, port string, err error) {
 		if byteIndex(host, ':') >= 0 {
 			return addrErr(hostport, tooManyColons)
 		}
-		if byteIndex(host, '%') >= 0 {
-			return addrErr(hostport, "missing brackets in address")
-		}
 	}
 	if byteIndex(hostport[j:], '[') >= 0 {
 		return addrErr(hostport, "unexpected '[' in address")
@@ -181,11 +179,12 @@ func splitHostZone(s string) (host, zone string) {
 }
 
 // JoinHostPort combines host and port into a network address of the
-// form "host:port" or, if host contains a colon or a percent sign,
-// "[host]:port".
+// form "host:port" or "host%zone:port", if host is a literal IPv6
+// address, "[host]:port" or [host%zone]:port.
 func JoinHostPort(host, port string) string {
-	// If host has colons or a percent sign, have to bracket it.
-	if byteIndex(host, ':') >= 0 || byteIndex(host, '%') >= 0 {
+	// We assume that host is a literal IPv6 address if host has
+	// colons.
+	if byteIndex(host, ':') >= 0 {
 		return "[" + host + "]:" + port
 	}
 	return host + ":" + port