diff --git a/api/prometheus/v1/api.go b/api/prometheus/v1/api.go
index a18d2c7b8..b77294778 100644
--- a/api/prometheus/v1/api.go
+++ b/api/prometheus/v1/api.go
@@ -232,9 +232,9 @@ type API interface {
 	// Flags returns the flag values that Prometheus was launched with.
 	Flags(ctx context.Context) (FlagsResult, error)
 	// LabelNames returns all the unique label names present in the block in sorted order.
-	LabelNames(ctx context.Context) ([]string, Warnings, error)
+	LabelNames(ctx context.Context, startTime time.Time, endTime time.Time) ([]string, Warnings, error)
 	// LabelValues performs a query for the values of the given label.
-	LabelValues(ctx context.Context, label string) (model.LabelValues, Warnings, error)
+	LabelValues(ctx context.Context, label string, startTime time.Time, endTime time.Time) (model.LabelValues, Warnings, error)
 	// Query performs a query for the given time.
 	Query(ctx context.Context, query string, ts time.Time) (model.Value, Warnings, error)
 	// QueryRange performs a query for the given range.
@@ -676,8 +676,12 @@ func (h *httpAPI) Runtimeinfo(ctx context.Context) (RuntimeinfoResult, error) {
 	return res, json.Unmarshal(body, &res)
 }
 
-func (h *httpAPI) LabelNames(ctx context.Context) ([]string, Warnings, error) {
+func (h *httpAPI) LabelNames(ctx context.Context, startTime time.Time, endTime time.Time) ([]string, Warnings, error) {
 	u := h.client.URL(epLabels, nil)
+	q := u.Query()
+	q.Set("start", formatTime(startTime))
+	q.Set("end", formatTime(endTime))
+
 	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
 	if err != nil {
 		return nil, nil, err
@@ -690,8 +694,12 @@ func (h *httpAPI) LabelNames(ctx context.Context) ([]string, Warnings, error) {
 	return labelNames, w, json.Unmarshal(body, &labelNames)
 }
 
-func (h *httpAPI) LabelValues(ctx context.Context, label string) (model.LabelValues, Warnings, error) {
+func (h *httpAPI) LabelValues(ctx context.Context, label string, startTime time.Time, endTime time.Time) (model.LabelValues, Warnings, error) {
 	u := h.client.URL(epLabelValues, map[string]string{"name": label})
+	q := u.Query()
+	q.Set("start", formatTime(startTime))
+	q.Set("end", formatTime(endTime))
+
 	req, err := http.NewRequest(http.MethodGet, u.String(), nil)
 	if err != nil {
 		return nil, nil, err
diff --git a/api/prometheus/v1/api_test.go b/api/prometheus/v1/api_test.go
index cb6eaa586..4bc4d53f5 100644
--- a/api/prometheus/v1/api_test.go
+++ b/api/prometheus/v1/api_test.go
@@ -153,13 +153,13 @@ func TestAPIs(t *testing.T) {
 
 	doLabelNames := func(label string) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
-			return promAPI.LabelNames(context.Background())
+			return promAPI.LabelNames(context.Background(), time.Now().Add(-100*time.Hour), time.Now())
 		}
 	}
 
 	doLabelValues := func(label string) func() (interface{}, Warnings, error) {
 		return func() (interface{}, Warnings, error) {
-			return promAPI.LabelValues(context.Background(), label)
+			return promAPI.LabelValues(context.Background(), label, time.Now().Add(-100*time.Hour), time.Now())
 		}
 	}