diff --git a/interop/grpc_testing/test.pb.go b/interop/grpc_testing/test.pb.go
index 1c8e33bc95a3..9b44623c25ae 100644
--- a/interop/grpc_testing/test.pb.go
+++ b/interop/grpc_testing/test.pb.go
@@ -712,10 +712,12 @@ type LoadBalancerStatsResponse struct {
 	// The number of completed RPCs for each peer.
 	RpcsByPeer map[string]int32 `protobuf:"bytes,1,rep,name=rpcs_by_peer,json=rpcsByPeer,proto3" json:"rpcs_by_peer,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"varint,2,opt,name=value,proto3"`
 	// The number of RPCs that failed to record a remote peer.
-	NumFailures          int32    `protobuf:"varint,2,opt,name=num_failures,json=numFailures,proto3" json:"num_failures,omitempty"`
-	XXX_NoUnkeyedLiteral struct{} `json:"-"`
-	XXX_unrecognized     []byte   `json:"-"`
-	XXX_sizecache        int32    `json:"-"`
+	NumFailures int32 `protobuf:"varint,2,opt,name=num_failures,json=numFailures,proto3" json:"num_failures,omitempty"`
+	// The number of completed RPCs for each method (UnaryCall or EmptyCall).
+	RpcsByMethod         map[string]*LoadBalancerStatsResponse_RpcsByPeer `protobuf:"bytes,3,rep,name=rpcs_by_method,json=rpcsByMethod,proto3" json:"rpcs_by_method,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"bytes,2,opt,name=value,proto3"`
+	XXX_NoUnkeyedLiteral struct{}                                         `json:"-"`
+	XXX_unrecognized     []byte                                           `json:"-"`
+	XXX_sizecache        int32                                            `json:"-"`
 }
 
 func (m *LoadBalancerStatsResponse) Reset()         { *m = LoadBalancerStatsResponse{} }
@@ -757,6 +759,53 @@ func (m *LoadBalancerStatsResponse) GetNumFailures() int32 {
 	return 0
 }
 
+func (m *LoadBalancerStatsResponse) GetRpcsByMethod() map[string]*LoadBalancerStatsResponse_RpcsByPeer {
+	if m != nil {
+		return m.RpcsByMethod
+	}
+	return nil
+}
+
+type LoadBalancerStatsResponse_RpcsByPeer struct {
+	// The number of completed RPCs for each peer.
+	RpcsByPeer           map[string]int32 `protobuf:"bytes,1,rep,name=rpcs_by_peer,json=rpcsByPeer,proto3" json:"rpcs_by_peer,omitempty" protobuf_key:"bytes,1,opt,name=key,proto3" protobuf_val:"varint,2,opt,name=value,proto3"`
+	XXX_NoUnkeyedLiteral struct{}         `json:"-"`
+	XXX_unrecognized     []byte           `json:"-"`
+	XXX_sizecache        int32            `json:"-"`
+}
+
+func (m *LoadBalancerStatsResponse_RpcsByPeer) Reset()         { *m = LoadBalancerStatsResponse_RpcsByPeer{} }
+func (m *LoadBalancerStatsResponse_RpcsByPeer) String() string { return proto.CompactTextString(m) }
+func (*LoadBalancerStatsResponse_RpcsByPeer) ProtoMessage()    {}
+func (*LoadBalancerStatsResponse_RpcsByPeer) Descriptor() ([]byte, []int) {
+	return fileDescriptor_534063719f48d90d, []int{11, 0}
+}
+
+func (m *LoadBalancerStatsResponse_RpcsByPeer) XXX_Unmarshal(b []byte) error {
+	return xxx_messageInfo_LoadBalancerStatsResponse_RpcsByPeer.Unmarshal(m, b)
+}
+func (m *LoadBalancerStatsResponse_RpcsByPeer) XXX_Marshal(b []byte, deterministic bool) ([]byte, error) {
+	return xxx_messageInfo_LoadBalancerStatsResponse_RpcsByPeer.Marshal(b, m, deterministic)
+}
+func (m *LoadBalancerStatsResponse_RpcsByPeer) XXX_Merge(src proto.Message) {
+	xxx_messageInfo_LoadBalancerStatsResponse_RpcsByPeer.Merge(m, src)
+}
+func (m *LoadBalancerStatsResponse_RpcsByPeer) XXX_Size() int {
+	return xxx_messageInfo_LoadBalancerStatsResponse_RpcsByPeer.Size(m)
+}
+func (m *LoadBalancerStatsResponse_RpcsByPeer) XXX_DiscardUnknown() {
+	xxx_messageInfo_LoadBalancerStatsResponse_RpcsByPeer.DiscardUnknown(m)
+}
+
+var xxx_messageInfo_LoadBalancerStatsResponse_RpcsByPeer proto.InternalMessageInfo
+
+func (m *LoadBalancerStatsResponse_RpcsByPeer) GetRpcsByPeer() map[string]int32 {
+	if m != nil {
+		return m.RpcsByPeer
+	}
+	return nil
+}
+
 func init() {
 	proto.RegisterEnum("grpc.testing.PayloadType", PayloadType_name, PayloadType_value)
 	proto.RegisterEnum("grpc.testing.GrpclbRouteType", GrpclbRouteType_name, GrpclbRouteType_value)
@@ -772,75 +821,82 @@ func init() {
 	proto.RegisterType((*StreamingOutputCallResponse)(nil), "grpc.testing.StreamingOutputCallResponse")
 	proto.RegisterType((*LoadBalancerStatsRequest)(nil), "grpc.testing.LoadBalancerStatsRequest")
 	proto.RegisterType((*LoadBalancerStatsResponse)(nil), "grpc.testing.LoadBalancerStatsResponse")
+	proto.RegisterMapType((map[string]*LoadBalancerStatsResponse_RpcsByPeer)(nil), "grpc.testing.LoadBalancerStatsResponse.RpcsByMethodEntry")
 	proto.RegisterMapType((map[string]int32)(nil), "grpc.testing.LoadBalancerStatsResponse.RpcsByPeerEntry")
+	proto.RegisterType((*LoadBalancerStatsResponse_RpcsByPeer)(nil), "grpc.testing.LoadBalancerStatsResponse.RpcsByPeer")
+	proto.RegisterMapType((map[string]int32)(nil), "grpc.testing.LoadBalancerStatsResponse.RpcsByPeer.RpcsByPeerEntry")
 }
 
 func init() { proto.RegisterFile("interop/grpc_testing/test.proto", fileDescriptor_534063719f48d90d) }
 
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+	0x29, 0x51, 0xce, 0x59, 0xc2, 0x94, 0x5b, 0x11, 0x56, 0x85, 0xcd, 0x09, 0x57, 0x51, 0xcf, 0x27,
+	0x7b, 0xf4, 0x08, 0x8a, 0xb3, 0x14, 0xad, 0x4b, 0x35, 0xd0, 0x29, 0x3d, 0x7b, 0x50, 0x98, 0x96,
+	0x95, 0x8d, 0xbc, 0x83, 0xa4, 0xa4, 0x53, 0xd8, 0x5e, 0xae, 0x26, 0x27, 0x0f, 0xc9, 0xc3, 0x79,
+	0x50, 0x0b, 0x75, 0xe9, 0x5b, 0xd6, 0xbc, 0x40, 0x80, 0xbc, 0xa2, 0x01, 0x97, 0x20, 0x37, 0xa2,
+	0x34, 0xc9, 0x5e, 0xeb, 0xc0, 0xee, 0x80, 0x33, 0x82, 0x5d, 0xdb, 0xb3, 0x4e, 0x3d, 0x3f, 0xe4,
+	0x87, 0xd8, 0x71, 0x92, 0x43, 0xba, 0x2a, 0x1d, 0xda, 0x39, 0x54, 0xd3, 0xa2, 0xc5, 0xec, 0x7e,
+	0x06, 0xff, 0xc7, 0x96, 0xc5, 0x88, 0x85, 0x39, 0x19, 0x19, 0xb1, 0x4f, 0x74, 0x7a, 0xa3, 0x31,
+	0x7a, 0x30, 0x55, 0xc7, 0xa1, 0xc5, 0x31, 0xd6, 0x4e, 0x01, 0x25, 0x31, 0xfa, 0x98, 0x61, 0x97,
+	0x70, 0xc2, 0xe4, 0x04, 0xce, 0xb8, 0xca, 0xb5, 0xa0, 0x5c, 0xde, 0x15, 0xd7, 0x58, 0x9c, 0xe1,
+	0x78, 0x26, 0x20, 0x11, 0x0d, 0x03, 0xed, 0xb7, 0xcc, 0x0c, 0xc2, 0x5e, 0xc8, 0x17, 0x0a, 0xbe,
+	0xeb, 0x54, 0x7e, 0x03, 0x3b, 0x13, 0x7f, 0x7f, 0x02, 0x55, 0xcd, 0xd4, 0xd6, 0xeb, 0xc5, 0x66,
+	0x6d, 0x3e, 0xca, 0x72, 0x49, 0x3a, 0x62, 0xcb, 0x65, 0xae, 0x3c, 0xc3, 0x77, 0x1f, 0x3a, 0xad,
+	0x0b, 0x7b, 0xa9, 0x24, 0xfd, 0xc3, 0x29, 0xd1, 0xbe, 0x05, 0xb5, 0x43, 0xf1, 0xa8, 0x85, 0x1d,
+	0xec, 0x99, 0x84, 0x89, 0x2c, 0x41, 0x42, 0xf9, 0x2e, 0x6c, 0x7a, 0xa1, 0x6b, 0x30, 0xdf, 0x0c,
+	0xe2, 0x56, 0xe6, 0xbd, 0xd0, 0xd5, 0x7d, 0x33, 0x10, 0xdd, 0xe4, 0xb6, 0x4b, 0x68, 0xc8, 0x8d,
+	0x80, 0x98, 0x49, 0x37, 0x63, 0xd1, 0x80, 0x98, 0xda, 0x9f, 0x59, 0xd8, 0x4d, 0x09, 0x1c, 0xc3,
+	0x7c, 0x0d, 0x25, 0x11, 0xd5, 0xb8, 0x18, 0x1b, 0x3e, 0x21, 0x4c, 0x55, 0x64, 0x17, 0x3e, 0x9f,
+	0xc7, 0x7a, 0xa3, 0x7b, 0x43, 0x40, 0x68, 0x8d, 0xfb, 0x84, 0xb0, 0xb6, 0xc7, 0xd9, 0x58, 0x07,
+	0x36, 0x11, 0xa0, 0xf7, 0xa0, 0x24, 0x40, 0x5f, 0x62, 0xdb, 0x09, 0x19, 0x49, 0x0e, 0x5a, 0xd1,
+	0x0b, 0xdd, 0xe3, 0x58, 0x84, 0x0c, 0x28, 0x27, 0xd9, 0x5d, 0xc2, 0xaf, 0xa8, 0x68, 0x9f, 0xc8,
+	0xff, 0xe5, 0x6a, 0xf9, 0xcf, 0xa4, 0x6f, 0x84, 0xa0, 0xc4, 0x66, 0x44, 0xd5, 0xdf, 0x15, 0x80,
+	0x29, 0x46, 0x34, 0x4a, 0xad, 0xb6, 0xb5, 0x7a, 0xb5, 0x7f, 0x57, 0x78, 0xf5, 0x05, 0x6c, 0x2d,
+	0xa8, 0x51, 0x05, 0xd6, 0x7f, 0x20, 0x63, 0xd9, 0xbb, 0x82, 0x2e, 0x96, 0xe8, 0x3e, 0xe4, 0xae,
+	0xb1, 0x13, 0x26, 0x6f, 0x52, 0xb4, 0x79, 0x9e, 0xf9, 0x42, 0xb9, 0xab, 0x7b, 0x00, 0xdb, 0x4b,
+	0xac, 0xa4, 0x04, 0x78, 0x39, 0x1b, 0xa0, 0xd8, 0x6c, 0xae, 0xce, 0xc1, 0x4c, 0xd2, 0x27, 0x5f,
+	0x43, 0x71, 0x66, 0xe0, 0x51, 0x05, 0x4a, 0x87, 0xbd, 0xb3, 0xbe, 0xde, 0x1e, 0x0c, 0x0e, 0x5a,
+	0x9d, 0x76, 0x65, 0x0d, 0x21, 0x28, 0x0f, 0xbb, 0x73, 0x32, 0x05, 0x01, 0x6c, 0xe8, 0x07, 0xdd,
+	0xa3, 0xde, 0x59, 0x25, 0xf3, 0x84, 0xc2, 0xd6, 0xc2, 0x15, 0x8d, 0x1e, 0xc2, 0xee, 0x89, 0xde,
+	0x3f, 0xec, 0xb4, 0x0c, 0xbd, 0x37, 0x3c, 0x6f, 0x1b, 0xe7, 0xaf, 0xfb, 0x6d, 0x63, 0xd8, 0x7d,
+	0xd5, 0xed, 0x7d, 0xd7, 0xad, 0xac, 0xa1, 0x77, 0xa1, 0xba, 0xac, 0x3e, 0x3e, 0xe8, 0x74, 0x5a,
+	0x07, 0x87, 0xaf, 0x2a, 0x4a, 0xba, 0xbb, 0xd0, 0xb5, 0xbb, 0x47, 0x95, 0x4c, 0xf3, 0x8f, 0x2c,
+	0x14, 0xcf, 0x49, 0xc0, 0xc5, 0xf3, 0x68, 0x9b, 0x04, 0x7d, 0x0a, 0x05, 0xf9, 0x87, 0x48, 0x0c,
+	0x31, 0xda, 0x59, 0xb8, 0x05, 0x84, 0xa2, 0x9a, 0x26, 0x44, 0xc7, 0x50, 0x18, 0x7a, 0x98, 0x45,
+	0x6e, 0x7b, 0xf3, 0x16, 0x73, 0x7f, 0x66, 0xaa, 0xef, 0xa4, 0x2b, 0xe3, 0x39, 0x74, 0x60, 0x27,
+	0xe5, 0x36, 0x41, 0xf5, 0x05, 0xa7, 0x1b, 0x6f, 0xe5, 0xea, 0x47, 0xb7, 0xb0, 0x8c, 0x72, 0x7d,
+	0xa2, 0x20, 0x1b, 0xd0, 0xf2, 0x13, 0x84, 0x1e, 0xdf, 0x10, 0x62, 0xf1, 0xc9, 0xab, 0xd6, 0xdf,
+	0x6e, 0x18, 0xa5, 0xaa, 0x8b, 0x54, 0xe5, 0xe3, 0xd0, 0x71, 0x8e, 0x42, 0xdf, 0x21, 0x3f, 0xfd,
+	0x6b, 0x35, 0xd5, 0x15, 0x59, 0x55, 0xf9, 0x25, 0x76, 0x2e, 0xff, 0x83, 0x54, 0xcd, 0x21, 0xdc,
+	0x1f, 0x7a, 0xb2, 0x83, 0x2e, 0xf1, 0x38, 0x19, 0x25, 0xa7, 0xe8, 0x05, 0x6c, 0xcf, 0xc9, 0x57,
+	0x3b, 0x4d, 0xcd, 0x9f, 0x53, 0xde, 0x80, 0x24, 0xb4, 0x09, 0xe5, 0x13, 0xc2, 0x0f, 0x1d, 0x9b,
+	0x78, 0x5c, 0x2a, 0xd0, 0x87, 0x6f, 0x9d, 0xd9, 0xa8, 0xb6, 0xc7, 0xb7, 0x9c, 0x6d, 0x6d, 0xad,
+	0xf5, 0xf4, 0xfb, 0x8f, 0x2d, 0x4a, 0x2d, 0x87, 0x34, 0x2c, 0xea, 0x60, 0xcf, 0x6a, 0x50, 0x66,
+	0xc9, 0x2f, 0x8a, 0xfd, 0xb4, 0xcf, 0x8b, 0x8b, 0x0d, 0xf9, 0x69, 0xf1, 0xec, 0xaf, 0x00, 0x00,
+	0x00, 0xff, 0xff, 0x8c, 0x0b, 0x8c, 0x16, 0x7d, 0x0c, 0x00, 0x00,
 }
diff --git a/interop/grpc_testing/test.proto b/interop/grpc_testing/test.proto
index f827a3ef2d64..21451047e513 100644
--- a/interop/grpc_testing/test.proto
+++ b/interop/grpc_testing/test.proto
@@ -214,10 +214,17 @@ message LoadBalancerStatsRequest {
 }
 
 message LoadBalancerStatsResponse {
+  message RpcsByPeer {
+    // The number of completed RPCs for each peer.
+    map<string, int32> rpcs_by_peer = 1;
+  }
+
   // The number of completed RPCs for each peer.
   map<string, int32> rpcs_by_peer = 1;
   // The number of RPCs that failed to record a remote peer.
   int32 num_failures = 2;
+  // The number of completed RPCs for each method (UnaryCall or EmptyCall).
+  map<string, RpcsByPeer> rpcs_by_method = 3;
 }
 
 // A service used to obtain stats for verifying LB behavior.
diff --git a/interop/xds/client/client.go b/interop/xds/client/client.go
index 44fbf1e6dbb3..27f954c30d28 100644
--- a/interop/xds/client/client.go
+++ b/interop/xds/client/client.go
@@ -23,13 +23,16 @@ import (
 	"context"
 	"flag"
 	"fmt"
+	"log"
 	"net"
+	"strings"
 	"sync"
 	"time"
 
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/grpclog"
 	testpb "google.golang.org/grpc/interop/grpc_testing"
+	"google.golang.org/grpc/metadata"
 	"google.golang.org/grpc/peer"
 	_ "google.golang.org/grpc/xds"
 )
@@ -39,18 +42,43 @@ type statsWatcherKey struct {
 	endID   int32
 }
 
+// rpcInfo contains the rpc type and the hostname where the response is received
+// from.
+type rpcInfo struct {
+	typ      string
+	hostname string
+}
+
 type statsWatcher struct {
 	rpcsByPeer    map[string]int32
+	rpcsByType    map[string]map[string]int32
 	numFailures   int32
 	remainingRpcs int32
-	c             chan *testpb.SimpleResponse
+	chanHosts     chan *rpcInfo
+}
+
+func (watcher *statsWatcher) buildResp() *testpb.LoadBalancerStatsResponse {
+	rpcsByType := make(map[string]*testpb.LoadBalancerStatsResponse_RpcsByPeer, len(watcher.rpcsByType))
+	for t, rpcsByPeer := range watcher.rpcsByType {
+		rpcsByType[t] = &testpb.LoadBalancerStatsResponse_RpcsByPeer{
+			RpcsByPeer: rpcsByPeer,
+		}
+	}
+
+	return &testpb.LoadBalancerStatsResponse{
+		NumFailures:  watcher.numFailures + watcher.remainingRpcs,
+		RpcsByPeer:   watcher.rpcsByPeer,
+		RpcsByMethod: rpcsByType,
+	}
 }
 
 var (
 	failOnFailedRPC = flag.Bool("fail_on_failed_rpc", false, "Fail client if any RPCs fail")
 	numChannels     = flag.Int("num_channels", 1, "Num of channels")
 	printResponse   = flag.Bool("print_response", false, "Write RPC response to stdout")
-	qps             = flag.Int("qps", 1, "QPS per channel")
+	qps             = flag.Int("qps", 1, "QPS per channel, for each type of RPC")
+	rpc             = flag.String("rpc", "UnaryCall", "Types of RPCs to make, ',' separated string. RPCs can be EmptyCall or UnaryCall")
+	rpcMetadata     = flag.String("metadata", "", "The metadata to send with RPC, in format EmptyCall:key1:value1,UnaryCall:key2:value2")
 	rpcTimeout      = flag.Duration("rpc_timeout", 20*time.Second, "Per RPC timeout")
 	server          = flag.String("server", "localhost:8080", "Address of server to connect to")
 	statsPort       = flag.Int("stats_port", 8081, "Port to expose peer distribution stats service")
@@ -75,9 +103,10 @@ func (s *statsService) GetClientStats(ctx context.Context, in *testpb.LoadBalanc
 	if !ok {
 		watcher = &statsWatcher{
 			rpcsByPeer:    make(map[string]int32),
+			rpcsByType:    make(map[string]map[string]int32),
 			numFailures:   0,
 			remainingRpcs: in.GetNumRpcs(),
-			c:             make(chan *testpb.SimpleResponse),
+			chanHosts:     make(chan *rpcInfo),
 		}
 		watchers[watcherKey] = watcher
 	}
@@ -95,25 +124,86 @@ func (s *statsService) GetClientStats(ctx context.Context, in *testpb.LoadBalanc
 	// Wait until the requested RPCs have all been recorded or timeout occurs.
 	for {
 		select {
-		case r := <-watcher.c:
-			if r != nil {
-				watcher.rpcsByPeer[(*r).GetHostname()]++
+		case info := <-watcher.chanHosts:
+			if info != nil {
+				watcher.rpcsByPeer[info.hostname]++
+
+				rpcsByPeerForType := watcher.rpcsByType[info.typ]
+				if rpcsByPeerForType == nil {
+					rpcsByPeerForType = make(map[string]int32)
+					watcher.rpcsByType[info.typ] = rpcsByPeerForType
+				}
+				rpcsByPeerForType[info.hostname]++
 			} else {
 				watcher.numFailures++
 			}
 			watcher.remainingRpcs--
 			if watcher.remainingRpcs == 0 {
-				return &testpb.LoadBalancerStatsResponse{NumFailures: watcher.numFailures + watcher.remainingRpcs, RpcsByPeer: watcher.rpcsByPeer}, nil
+				return watcher.buildResp(), nil
 			}
 		case <-ctx.Done():
 			grpclog.Info("Timed out, returning partial stats")
-			return &testpb.LoadBalancerStatsResponse{NumFailures: watcher.numFailures + watcher.remainingRpcs, RpcsByPeer: watcher.rpcsByPeer}, nil
+			return watcher.buildResp(), nil
+		}
+	}
+}
+
+const (
+	unaryCall string = "UnaryCall"
+	emptyCall string = "EmptyCall"
+)
+
+func parseRPCTypes(rpcStr string) (ret []string) {
+	if len(rpcStr) == 0 {
+		return []string{unaryCall}
+	}
+
+	rpcs := strings.Split(rpcStr, ",")
+	for _, r := range rpcs {
+		switch r {
+		case unaryCall, emptyCall:
+			ret = append(ret, r)
+		default:
+			flag.PrintDefaults()
+			log.Fatalf("unsupported RPC type: %v", r)
+		}
+	}
+	return
+}
+
+type rpcConfig struct {
+	typ string
+	md  metadata.MD
+}
+
+// parseRPCMetadata turns EmptyCall:key1:value1 into
+//   {typ: emptyCall, md: {key1:value1}}.
+func parseRPCMetadata(rpcMetadataStr string, rpcs []string) []*rpcConfig {
+	rpcMetadataSplit := strings.Split(rpcMetadataStr, ",")
+	rpcsToMD := make(map[string][]string)
+	for _, rm := range rpcMetadataSplit {
+		rmSplit := strings.Split(rm, ":")
+		if len(rmSplit)%2 != 1 {
+			log.Fatalf("invalid metadata config %v, want EmptyCall:key1:value1", rm)
+		}
+		rpcsToMD[rmSplit[0]] = append(rpcsToMD[rmSplit[0]], rmSplit[1:]...)
+	}
+	ret := make([]*rpcConfig, 0, len(rpcs))
+	for _, rpcT := range rpcs {
+		rpcC := &rpcConfig{
+			typ: rpcT,
 		}
+		if md := rpcsToMD[string(rpcT)]; len(md) > 0 {
+			rpcC.md = metadata.Pairs(md...)
+		}
+		ret = append(ret, rpcC)
 	}
+	return ret
 }
 
 func main() {
 	flag.Parse()
+	rpcCfgs := parseRPCMetadata(*rpcMetadata, parseRPCTypes(*rpc))
 
 	lis, err := net.Listen("tcp", fmt.Sprintf(":%d", *statsPort))
 	if err != nil {
@@ -135,16 +225,52 @@ func main() {
 	}
 	ticker := time.NewTicker(time.Second / time.Duration(*qps**numChannels))
 	defer ticker.Stop()
-	sendRPCs(clients, ticker)
+	sendRPCs(clients, rpcCfgs, ticker)
 }
 
-func sendRPCs(clients []testpb.TestServiceClient, ticker *time.Ticker) {
+func makeOneRPC(c testpb.TestServiceClient, cfg *rpcConfig) (*peer.Peer, *rpcInfo, error) {
+	ctx, cancel := context.WithTimeout(context.Background(), *rpcTimeout)
+	defer cancel()
+
+	if len(cfg.md) != 0 {
+		ctx = metadata.NewOutgoingContext(ctx, cfg.md)
+	}
+	info := rpcInfo{typ: cfg.typ}
+
+	var (
+		p      peer.Peer
+		header metadata.MD
+		err    error
+	)
+	switch cfg.typ {
+	case unaryCall:
+		var resp *testpb.SimpleResponse
+		resp, err = c.UnaryCall(ctx, &testpb.SimpleRequest{FillServerId: true}, grpc.Peer(&p), grpc.Header(&header))
+		// For UnaryCall, also read hostname from response, in case the server
+		// isn't updated to send headers.
+		if resp != nil {
+			info.hostname = resp.Hostname
+		}
+	case emptyCall:
+		_, err = c.EmptyCall(ctx, &testpb.Empty{}, grpc.Peer(&p), grpc.Header(&header))
+	}
+	if err != nil {
+		return nil, nil, err
+	}
+
+	hosts := header["hostname"]
+	if len(hosts) > 0 {
+		info.hostname = hosts[0]
+	}
+	return &p, &info, err
+}
+
+func sendRPCs(clients []testpb.TestServiceClient, cfgs []*rpcConfig, ticker *time.Ticker) {
 	var i int
 	for range ticker.C {
 		go func(i int) {
-			c := clients[i]
-			ctx, cancel := context.WithTimeout(context.Background(), *rpcTimeout)
-			p := new(peer.Peer)
+			// Get and increment request ID, and save a list of watchers that
+			// are interested in this RPC.
 			mu.Lock()
 			savedRequestID := currentRequestID
 			currentRequestID++
@@ -155,20 +281,32 @@ func sendRPCs(clients []testpb.TestServiceClient, ticker *time.Ticker) {
 				}
 			}
 			mu.Unlock()
-			r, err := c.UnaryCall(ctx, &testpb.SimpleRequest{FillServerId: true}, grpc.Peer(p))
 
-			success := err == nil
-			cancel()
+			c := clients[i]
 
-			for _, watcher := range savedWatchers {
-				watcher.c <- r
-			}
+			for _, cfg := range cfgs {
+				p, info, err := makeOneRPC(c, cfg)
 
-			if err != nil && *failOnFailedRPC {
-				grpclog.Fatalf("RPC failed: %v", err)
-			}
-			if success && *printResponse {
-				fmt.Printf("Greeting: Hello world, this is %s, from %v\n", r.GetHostname(), p.Addr)
+				for _, watcher := range savedWatchers {
+					// This sends an empty string if the RPC failed.
+					watcher.chanHosts <- info
+				}
+				if err != nil && *failOnFailedRPC {
+					grpclog.Fatalf("RPC failed: %v", err)
+				}
+				if *printResponse {
+					if err == nil {
+						if cfg.typ == unaryCall {
+							// Need to keep this format, because some tests are
+							// relying on stdout.
+							fmt.Printf("Greeting: Hello world, this is %s, from %v\n", info.hostname, p.Addr)
+						} else {
+							fmt.Printf("RPC %q, from host %s, addr %v\n", cfg.typ, info.hostname, p.Addr)
+						}
+					} else {
+						fmt.Printf("RPC %q, failed with %v\n", cfg.typ, err)
+					}
+				}
 			}
 		}(i)
 		i = (i + 1) % len(clients)
diff --git a/interop/xds/server/server.go b/interop/xds/server/server.go
index 34ada6b542e6..cfb2016f8670 100644
--- a/interop/xds/server/server.go
+++ b/interop/xds/server/server.go
@@ -30,6 +30,7 @@ import (
 	"google.golang.org/grpc"
 	"google.golang.org/grpc/grpclog"
 	testpb "google.golang.org/grpc/interop/grpc_testing"
+	"google.golang.org/grpc/metadata"
 )
 
 var (
@@ -50,7 +51,13 @@ type server struct {
 	testpb.UnimplementedTestServiceServer
 }
 
+func (s *server) EmptyCall(ctx context.Context, _ *testpb.Empty) (*testpb.Empty, error) {
+	grpc.SetHeader(ctx, metadata.Pairs("hostname", hostname))
+	return &testpb.Empty{}, nil
+}
+
 func (s *server) UnaryCall(ctx context.Context, in *testpb.SimpleRequest) (*testpb.SimpleResponse, error) {
+	grpc.SetHeader(ctx, metadata.Pairs("hostname", hostname))
 	return &testpb.SimpleResponse{ServerId: *serverID, Hostname: hostname}, nil
 }