diff --git a/config/http_config.go b/config/http_config.go
index 4a926e8d..7a67a0a6 100644
--- a/config/http_config.go
+++ b/config/http_config.go
@@ -30,7 +30,7 @@ import (
 	"sync"
 	"time"
 
-	"github.com/mwitkow/go-conntrack"
+	conntrack "github.com/mwitkow/go-conntrack"
 	"golang.org/x/net/http/httpproxy"
 	"golang.org/x/net/http2"
 	"golang.org/x/oauth2"
diff --git a/expfmt/decode_test.go b/expfmt/decode_test.go
index fff57ab6..3c023f53 100644
--- a/expfmt/decode_test.go
+++ b/expfmt/decode_test.go
@@ -17,6 +17,7 @@ import (
 	"bufio"
 	"errors"
 	"io"
+	"math"
 	"net/http"
 	"reflect"
 	"sort"
@@ -104,9 +105,10 @@ func TestProtoDecoder(t *testing.T) {
 	testTime := model.Now()
 
 	scenarios := []struct {
-		in       string
-		expected model.Vector
-		fail     bool
+		in             string
+		expected       model.Vector
+		legacyNameFail bool
+		fail           bool
 	}{
 		{
 			in: "",
@@ -332,6 +334,30 @@ func TestProtoDecoder(t *testing.T) {
 				},
 			},
 		},
+		{
+			in:             "\xa8\x01\n\ngauge.name\x12\x11gauge\ndoc\nstr\"ing\x18\x01\"T\n\x1b\n\x06name.1\x12\x11val with\nnew line\n*\n\x06name*2\x12 val with \\backslash and \"quotes\"\x12\t\t\x00\x00\x00\x00\x00\x00\xf0\x7f\"/\n\x10\n\x06name.1\x12\x06Björn\n\x10\n\x06name*2\x12\x06佖佥\x12\t\t\xd1\xcfD\xb9\xd0\x05\xc2H",
+			legacyNameFail: true,
+			expected: model.Vector{
+				&model.Sample{
+					Metric: model.Metric{
+						model.MetricNameLabel: "gauge.name",
+						"name.1":              "val with\nnew line",
+						"name*2":              "val with \\backslash and \"quotes\"",
+					},
+					Value:     model.SampleValue(math.Inf(+1)),
+					Timestamp: testTime,
+				},
+				&model.Sample{
+					Metric: model.Metric{
+						model.MetricNameLabel: "gauge.name",
+						"name.1":              "Björn",
+						"name*2":              "佖佥",
+					},
+					Value:     3.14e42,
+					Timestamp: testTime,
+				},
+			},
+		},
 	}
 
 	for i, scenario := range scenarios {
@@ -344,11 +370,31 @@ func TestProtoDecoder(t *testing.T) {
 
 		var all model.Vector
 		for {
+			model.NameValidationScheme = model.LegacyValidation
 			var smpls model.Vector
 			err := dec.Decode(&smpls)
 			if err != nil && errors.Is(err, io.EOF) {
 				break
 			}
+			if scenario.legacyNameFail {
+				if err == nil {
+					t.Fatal("Expected error when decoding without UTF-8 support enabled but got none")
+				}
+				model.NameValidationScheme = model.UTF8Validation
+				dec = &SampleDecoder{
+					Dec: &protoDecoder{r: strings.NewReader(scenario.in)},
+					Opts: &DecodeOptions{
+						Timestamp: testTime,
+					},
+				}
+				err = dec.Decode(&smpls)
+				if errors.Is(err, io.EOF) {
+					break
+				}
+				if err != nil {
+					t.Fatalf("Unexpected error when decoding with UTF-8 support: %v", err)
+				}
+			}
 			if scenario.fail {
 				if err == nil {
 					t.Fatal("Expected error but got none")
diff --git a/expfmt/expfmt.go b/expfmt/expfmt.go
index c4cb20f0..d866b474 100644
--- a/expfmt/expfmt.go
+++ b/expfmt/expfmt.go
@@ -17,7 +17,13 @@ package expfmt
 // Format specifies the HTTP content type of the different wire protocols.
 type Format string
 
-// Constants to assemble the Content-Type values for the different wire protocols.
+// Constants to assemble the Content-Type values for the different wire
+// protocols. The Content-Type strings here are all for the legacy exposition
+// formats, where valid characters for metric names and label names are limited.
+// Support for arbitrary UTF-8 characters in those names is already partially
+// implemented in this module (see model.ValidationScheme), but to actually use
+// it on the wire, new content-type strings will have to be agreed upon and
+// added here.
 const (
 	TextVersion              = "0.0.4"
 	ProtoType                = `application/vnd.google.protobuf`
diff --git a/expfmt/openmetrics_create.go b/expfmt/openmetrics_create.go
index 21cdddcf..5622578e 100644
--- a/expfmt/openmetrics_create.go
+++ b/expfmt/openmetrics_create.go
@@ -35,6 +35,18 @@ import (
 // sanity checks. If the input contains duplicate metrics or invalid metric or
 // label names, the conversion will result in invalid text format output.
 //
+// If metric names conform to the legacy validation pattern, they will be placed
+// outside the brackets in the traditional way, like `foo{}`. If the metric name
+// fails the legacy validation check, it will be placed quoted inside the
+// brackets: `{"foo"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
+// Similar to metric names, if label names conform to the legacy validation
+// pattern, they will be unquoted as normal, like `foo{bar="baz"}`. If the label
+// name fails the legacy validation check, it will be quoted:
+// `foo{"bar"="baz"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
 // This function fulfills the type 'expfmt.encoder'.
 //
 // Note that OpenMetrics requires a final `# EOF` line. Since this function acts
@@ -98,7 +110,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 		if err != nil {
 			return
 		}
-		n, err = w.WriteString(shortName)
+		n, err = writeName(w, shortName)
 		written += n
 		if err != nil {
 			return
@@ -124,7 +136,7 @@ func MetricFamilyToOpenMetrics(out io.Writer, in *dto.MetricFamily) (written int
 	if err != nil {
 		return
 	}
-	n, err = w.WriteString(shortName)
+	n, err = writeName(w, shortName)
 	written += n
 	if err != nil {
 		return
@@ -303,21 +315,9 @@ func writeOpenMetricsSample(
 	floatValue float64, intValue uint64, useIntValue bool,
 	exemplar *dto.Exemplar,
 ) (int, error) {
-	var written int
-	n, err := w.WriteString(name)
-	written += n
-	if err != nil {
-		return written, err
-	}
-	if suffix != "" {
-		n, err = w.WriteString(suffix)
-		written += n
-		if err != nil {
-			return written, err
-		}
-	}
-	n, err = writeOpenMetricsLabelPairs(
-		w, metric.Label, additionalLabelName, additionalLabelValue,
+	written := 0
+	n, err := writeOpenMetricsNameAndLabelPairs(
+		w, name+suffix, metric.Label, additionalLabelName, additionalLabelValue,
 	)
 	written += n
 	if err != nil {
@@ -365,27 +365,58 @@ func writeOpenMetricsSample(
 	return written, nil
 }
 
-// writeOpenMetricsLabelPairs works like writeOpenMetrics but formats the float
-// in OpenMetrics style.
-func writeOpenMetricsLabelPairs(
+// writeOpenMetricsNameAndLabelPairs works like writeOpenMetricsSample but
+// formats the float in OpenMetrics style.
+func writeOpenMetricsNameAndLabelPairs(
 	w enhancedWriter,
+	name string,
 	in []*dto.LabelPair,
 	additionalLabelName string, additionalLabelValue float64,
 ) (int, error) {
-	if len(in) == 0 && additionalLabelName == "" {
-		return 0, nil
-	}
 	var (
-		written   int
-		separator byte = '{'
+		written            int
+		separator          byte = '{'
+		metricInsideBraces      = false
 	)
+
+	if name != "" {
+		// If the name does not pass the legacy validity check, we must put the
+		// metric name inside the braces, quoted.
+		if !model.IsValidLegacyMetricName(model.LabelValue(name)) {
+			metricInsideBraces = true
+			err := w.WriteByte(separator)
+			written++
+			if err != nil {
+				return written, err
+			}
+			separator = ','
+		}
+
+		n, err := writeName(w, name)
+		written += n
+		if err != nil {
+			return written, err
+		}
+	}
+
+	if len(in) == 0 && additionalLabelName == "" {
+		if metricInsideBraces {
+			err := w.WriteByte('}')
+			written++
+			if err != nil {
+				return written, err
+			}
+		}
+		return written, nil
+	}
+
 	for _, lp := range in {
 		err := w.WriteByte(separator)
 		written++
 		if err != nil {
 			return written, err
 		}
-		n, err := w.WriteString(lp.GetName())
+		n, err := writeName(w, lp.GetName())
 		written += n
 		if err != nil {
 			return written, err
@@ -451,7 +482,7 @@ func writeExemplar(w enhancedWriter, e *dto.Exemplar) (int, error) {
 	if err != nil {
 		return written, err
 	}
-	n, err = writeOpenMetricsLabelPairs(w, e.Label, "", 0)
+	n, err = writeOpenMetricsNameAndLabelPairs(w, "", e.Label, "", 0)
 	written += n
 	if err != nil {
 		return written, err
diff --git a/expfmt/openmetrics_create_test.go b/expfmt/openmetrics_create_test.go
index ab1e8616..7b201655 100644
--- a/expfmt/openmetrics_create_test.go
+++ b/expfmt/openmetrics_create_test.go
@@ -82,7 +82,79 @@ name{labelname="val1",basename="basevalue"} 42.0
 name{labelname="val2",basename="basevalue"} 0.23 1.23456789e+06
 `,
 		},
-		// 1: Gauge, some escaping required, +Inf as value, multi-byte characters in label values.
+		// 1: Dots in name
+		{
+			in: &dto.MetricFamily{
+				Name: proto.String("name.with.dots"),
+				Help: proto.String("boring help"),
+				Type: dto.MetricType_COUNTER.Enum(),
+				Metric: []*dto.Metric{
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("labelname"),
+								Value: proto.String("val1"),
+							},
+							{
+								Name:  proto.String("basename"),
+								Value: proto.String("basevalue"),
+							},
+						},
+						Counter: &dto.Counter{
+							Value: proto.Float64(42),
+						},
+					},
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("labelname"),
+								Value: proto.String("val2"),
+							},
+							{
+								Name:  proto.String("basename"),
+								Value: proto.String("basevalue"),
+							},
+						},
+						Counter: &dto.Counter{
+							Value: proto.Float64(.23),
+						},
+						TimestampMs: proto.Int64(1234567890),
+					},
+				},
+			},
+			out: `# HELP "name.with.dots" boring help
+# TYPE "name.with.dots" unknown
+{"name.with.dots",labelname="val1",basename="basevalue"} 42.0
+{"name.with.dots",labelname="val2",basename="basevalue"} 0.23 1.23456789e+06
+`,
+		},
+		// 2: Dots in name, no labels
+		{
+			in: &dto.MetricFamily{
+				Name: proto.String("name.with.dots"),
+				Help: proto.String("boring help"),
+				Type: dto.MetricType_COUNTER.Enum(),
+				Metric: []*dto.Metric{
+					{
+						Counter: &dto.Counter{
+							Value: proto.Float64(42),
+						},
+					},
+					{
+						Counter: &dto.Counter{
+							Value: proto.Float64(.23),
+						},
+						TimestampMs: proto.Int64(1234567890),
+					},
+				},
+			},
+			out: `# HELP "name.with.dots" boring help
+# TYPE "name.with.dots" unknown
+{"name.with.dots"} 42.0
+{"name.with.dots"} 0.23 1.23456789e+06
+`,
+		},
+		// 3: Gauge, some escaping required, +Inf as value, multi-byte characters in label values.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("gauge_name"),
@@ -127,7 +199,52 @@ gauge_name{name_1="val with\nnew line",name_2="val with \\backslash and \"quotes
 gauge_name{name_1="Björn",name_2="佖佥"} 3.14e+42
 `,
 		},
-		// 2: Unknown, no help, one sample with no labels and -Inf as value, another sample with one label.
+		// 4: Gauge, utf8, some escaping required, +Inf as value, multi-byte characters in label values.
+		{
+			in: &dto.MetricFamily{
+				Name: proto.String("gauge.name\""),
+				Help: proto.String("gauge\ndoc\nstr\"ing"),
+				Type: dto.MetricType_GAUGE.Enum(),
+				Metric: []*dto.Metric{
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("name.1"),
+								Value: proto.String("val with\nnew line"),
+							},
+							{
+								Name:  proto.String("name*2"),
+								Value: proto.String("val with \\backslash and \"quotes\""),
+							},
+						},
+						Gauge: &dto.Gauge{
+							Value: proto.Float64(math.Inf(+1)),
+						},
+					},
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("name.1"),
+								Value: proto.String("Björn"),
+							},
+							{
+								Name:  proto.String("name*2"),
+								Value: proto.String("佖佥"),
+							},
+						},
+						Gauge: &dto.Gauge{
+							Value: proto.Float64(3.14e42),
+						},
+					},
+				},
+			},
+			out: `# HELP "gauge.name\"" gauge\ndoc\nstr\"ing
+# TYPE "gauge.name\"" gauge
+{"gauge.name\"","name.1"="val with\nnew line","name*2"="val with \\backslash and \"quotes\""} +Inf
+{"gauge.name\"","name.1"="Björn","name*2"="佖佥"} 3.14e+42
+`,
+		},
+		// 5: Unknown, no help, one sample with no labels and -Inf as value, another sample with one label.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("unknown_name"),
@@ -156,7 +273,7 @@ unknown_name -Inf
 unknown_name{name_1="value 1"} -1.23e-45
 `,
 		},
-		// 3: Summary.
+		// 6: Summary.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("summary_name"),
@@ -229,7 +346,7 @@ summary_name_sum{name_1="value 1",name_2="value 2"} 2010.1971
 summary_name_count{name_1="value 1",name_2="value 2"} 4711
 `,
 		},
-		// 4: Histogram
+		// 7: Histogram
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("request_duration_microseconds"),
@@ -277,7 +394,7 @@ request_duration_microseconds_sum 1.7560473e+06
 request_duration_microseconds_count 2693
 `,
 		},
-		// 5: Histogram with missing +Inf bucket.
+		// 8: Histogram with missing +Inf bucket.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("request_duration_microseconds"),
@@ -321,7 +438,7 @@ request_duration_microseconds_sum 1.7560473e+06
 request_duration_microseconds_count 2693
 `,
 		},
-		// 6: Histogram with missing +Inf bucket but with different exemplars.
+		// 9: Histogram with missing +Inf bucket but with different exemplars.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("request_duration_microseconds"),
@@ -388,7 +505,7 @@ request_duration_microseconds_sum 1.7560473e+06
 request_duration_microseconds_count 2693
 `,
 		},
-		// 7: Simple Counter.
+		// 10: Simple Counter.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("foos_total"),
@@ -407,7 +524,7 @@ request_duration_microseconds_count 2693
 foos_total 42.0
 `,
 		},
-		// 8: No metric.
+		// 11: No metric.
 		{
 			in: &dto.MetricFamily{
 				Name:   proto.String("name_total"),
diff --git a/expfmt/text_create.go b/expfmt/text_create.go
index 2946b8f1..f9b8265a 100644
--- a/expfmt/text_create.go
+++ b/expfmt/text_create.go
@@ -62,6 +62,18 @@ var (
 // contains duplicate metrics or invalid metric or label names, the conversion
 // will result in invalid text format output.
 //
+// If metric names conform to the legacy validation pattern, they will be placed
+// outside the brackets in the traditional way, like `foo{}`. If the metric name
+// fails the legacy validation check, it will be placed quoted inside the
+// brackets: `{"foo"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
+// Similar to metric names, if label names conform to the legacy validation
+// pattern, they will be unquoted as normal, like `foo{bar="baz"}`. If the label
+// name fails the legacy validation check, it will be quoted:
+// `foo{"bar"="baz"}`. As stated above, the input is assumed to be santized and
+// no error will be thrown in this case.
+//
 // This method fulfills the type 'prometheus.encoder'.
 func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err error) {
 	// Fail-fast checks.
@@ -98,7 +110,7 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err e
 		if err != nil {
 			return
 		}
-		n, err = w.WriteString(name)
+		n, err = writeName(w, name)
 		written += n
 		if err != nil {
 			return
@@ -124,7 +136,7 @@ func MetricFamilyToText(out io.Writer, in *dto.MetricFamily) (written int, err e
 	if err != nil {
 		return
 	}
-	n, err = w.WriteString(name)
+	n, err = writeName(w, name)
 	written += n
 	if err != nil {
 		return
@@ -280,21 +292,9 @@ func writeSample(
 	additionalLabelName string, additionalLabelValue float64,
 	value float64,
 ) (int, error) {
-	var written int
-	n, err := w.WriteString(name)
-	written += n
-	if err != nil {
-		return written, err
-	}
-	if suffix != "" {
-		n, err = w.WriteString(suffix)
-		written += n
-		if err != nil {
-			return written, err
-		}
-	}
-	n, err = writeLabelPairs(
-		w, metric.Label, additionalLabelName, additionalLabelValue,
+	written := 0
+	n, err := writeNameAndLabelPairs(
+		w, name+suffix, metric.Label, additionalLabelName, additionalLabelValue,
 	)
 	written += n
 	if err != nil {
@@ -330,32 +330,64 @@ func writeSample(
 	return written, nil
 }
 
-// writeLabelPairs converts a slice of LabelPair proto messages plus the
-// explicitly given additional label pair into text formatted as required by the
-// text format and writes it to 'w'. An empty slice in combination with an empty
-// string 'additionalLabelName' results in nothing being written. Otherwise, the
-// label pairs are written, escaped as required by the text format, and enclosed
-// in '{...}'. The function returns the number of bytes written and any error
-// encountered.
-func writeLabelPairs(
+// writeNameAndLabelPairs converts a slice of LabelPair proto messages plus the
+// explicitly given metric name and additional label pair into text formatted as
+// required by the text format and writes it to 'w'. An empty slice in
+// combination with an empty string 'additionalLabelName' results in nothing
+// being written. Otherwise, the label pairs are written, escaped as required by
+// the text format, and enclosed in '{...}'. The function returns the number of
+// bytes written and any error encountered. If the metric name is not
+// legacy-valid, it will be put inside the brackets as well. Legacy-invalid
+// label names will also be quoted.
+func writeNameAndLabelPairs(
 	w enhancedWriter,
+	name string,
 	in []*dto.LabelPair,
 	additionalLabelName string, additionalLabelValue float64,
 ) (int, error) {
-	if len(in) == 0 && additionalLabelName == "" {
-		return 0, nil
-	}
 	var (
-		written   int
-		separator byte = '{'
+		written            int
+		separator          byte = '{'
+		metricInsideBraces      = false
 	)
+
+	if name != "" {
+		// If the name does not pass the legacy validity check, we must put the
+		// metric name inside the braces.
+		if !model.IsValidLegacyMetricName(model.LabelValue(name)) {
+			metricInsideBraces = true
+			err := w.WriteByte(separator)
+			written++
+			if err != nil {
+				return written, err
+			}
+			separator = ','
+		}
+		n, err := writeName(w, name)
+		written += n
+		if err != nil {
+			return written, err
+		}
+	}
+
+	if len(in) == 0 && additionalLabelName == "" {
+		if metricInsideBraces {
+			err := w.WriteByte('}')
+			written++
+			if err != nil {
+				return written, err
+			}
+		}
+		return written, nil
+	}
+
 	for _, lp := range in {
 		err := w.WriteByte(separator)
 		written++
 		if err != nil {
 			return written, err
 		}
-		n, err := w.WriteString(lp.GetName())
+		n, err := writeName(w, lp.GetName())
 		written += n
 		if err != nil {
 			return written, err
@@ -462,3 +494,27 @@ func writeInt(w enhancedWriter, i int64) (int, error) {
 	numBufPool.Put(bp)
 	return written, err
 }
+
+// writeName writes a string as-is if it complies with the legacy naming
+// scheme, or escapes it in double quotes if not.
+func writeName(w enhancedWriter, name string) (int, error) {
+	if model.IsValidLegacyMetricName(model.LabelValue(name)) {
+		return w.WriteString(name)
+	}
+	var written int
+	var err error
+	err = w.WriteByte('"')
+	written++
+	if err != nil {
+		return written, err
+	}
+	var n int
+	n, err = writeEscapedString(w, name, true)
+	written += n
+	if err != nil {
+		return written, err
+	}
+	err = w.WriteByte('"')
+	written++
+	return written, err
+}
diff --git a/expfmt/text_create_test.go b/expfmt/text_create_test.go
index 8d3ac3d1..41bd408c 100644
--- a/expfmt/text_create_test.go
+++ b/expfmt/text_create_test.go
@@ -120,7 +120,52 @@ gauge_name{name_1="val with\nnew line",name_2="val with \\backslash and \"quotes
 gauge_name{name_1="Björn",name_2="佖佥"} 3.14e+42
 `,
 		},
-		// 2: Untyped, no help, one sample with no labels and -Inf as value, another sample with one label.
+		// 2: Gauge, utf8, +Inf as value, multi-byte characters in label values.
+		{
+			in: &dto.MetricFamily{
+				Name: proto.String("gauge.name"),
+				Help: proto.String("gauge\ndoc\nstr\"ing"),
+				Type: dto.MetricType_GAUGE.Enum(),
+				Metric: []*dto.Metric{
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("name.1"),
+								Value: proto.String("val with\nnew line"),
+							},
+							{
+								Name:  proto.String("name*2"),
+								Value: proto.String("val with \\backslash and \"quotes\""),
+							},
+						},
+						Gauge: &dto.Gauge{
+							Value: proto.Float64(math.Inf(+1)),
+						},
+					},
+					{
+						Label: []*dto.LabelPair{
+							{
+								Name:  proto.String("name.1"),
+								Value: proto.String("Björn"),
+							},
+							{
+								Name:  proto.String("name*2"),
+								Value: proto.String("佖佥"),
+							},
+						},
+						Gauge: &dto.Gauge{
+							Value: proto.Float64(3.14e42),
+						},
+					},
+				},
+			},
+			out: `# HELP "gauge.name" gauge\ndoc\nstr"ing
+# TYPE "gauge.name" gauge
+{"gauge.name","name.1"="val with\nnew line","name*2"="val with \\backslash and \"quotes\""} +Inf
+{"gauge.name","name.1"="Björn","name*2"="佖佥"} 3.14e+42
+`,
+		},
+		// 3: Untyped, no help, one sample with no labels and -Inf as value, another sample with one label.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("untyped_name"),
@@ -149,7 +194,7 @@ untyped_name -Inf
 untyped_name{name_1="value 1"} -1.23e-45
 `,
 		},
-		// 3: Summary.
+		// 4: Summary.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("summary_name"),
@@ -222,7 +267,7 @@ summary_name_sum{name_1="value 1",name_2="value 2"} 2010.1971
 summary_name_count{name_1="value 1",name_2="value 2"} 4711
 `,
 		},
-		// 4: Histogram
+		// 5: Histogram
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("request_duration_microseconds"),
@@ -270,7 +315,7 @@ request_duration_microseconds_sum 1.7560473e+06
 request_duration_microseconds_count 2693
 `,
 		},
-		// 5: Histogram with missing +Inf bucket.
+		// 6: Histogram with missing +Inf bucket.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("request_duration_microseconds"),
@@ -314,7 +359,7 @@ request_duration_microseconds_sum 1.7560473e+06
 request_duration_microseconds_count 2693
 `,
 		},
-		// 6: No metric type, should result in default type Counter.
+		// 7: No metric type, should result in default type Counter.
 		{
 			in: &dto.MetricFamily{
 				Name: proto.String("name"),
diff --git a/model/labels.go b/model/labels.go
index ef895633..73dafe43 100644
--- a/model/labels.go
+++ b/model/labels.go
@@ -97,17 +97,25 @@ var LabelNameRE = regexp.MustCompile("^[a-zA-Z_][a-zA-Z0-9_]*$")
 // therewith.
 type LabelName string
 
-// IsValid is true iff the label name matches the pattern of LabelNameRE. This
-// method, however, does not use LabelNameRE for the check but a much faster
-// hardcoded implementation.
+// IsValid returns true iff name matches the pattern of LabelNameRE for legacy
+// names, and iff it's valid UTF-8 if NameValidationScheme is set to
+// UTF8Validation. For the legacy matching, it does not use LabelNameRE for the
+// check but a much faster hardcoded implementation.
 func (ln LabelName) IsValid() bool {
 	if len(ln) == 0 {
 		return false
 	}
-	for i, b := range ln {
-		if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) {
-			return false
+	switch NameValidationScheme {
+	case LegacyValidation:
+		for i, b := range ln {
+			if !((b >= 'a' && b <= 'z') || (b >= 'A' && b <= 'Z') || b == '_' || (b >= '0' && b <= '9' && i > 0)) {
+				return false
+			}
 		}
+	case UTF8Validation:
+		return utf8.ValidString(string(ln))
+	default:
+		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", NameValidationScheme))
 	}
 	return true
 }
diff --git a/model/labels_test.go b/model/labels_test.go
index c49d8e7c..5ec94a40 100644
--- a/model/labels_test.go
+++ b/model/labels_test.go
@@ -92,49 +92,68 @@ func BenchmarkLabelValues(b *testing.B) {
 
 func TestLabelNameIsValid(t *testing.T) {
 	scenarios := []struct {
-		ln    LabelName
-		valid bool
+		ln          LabelName
+		legacyValid bool
+		utf8Valid   bool
 	}{
 		{
-			ln:    "Avalid_23name",
-			valid: true,
+			ln:          "Avalid_23name",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			ln:    "_Avalid_23name",
-			valid: true,
+			ln:          "_Avalid_23name",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			ln:    "1valid_23name",
-			valid: false,
+			ln:          "1valid_23name",
+			legacyValid: false,
+			utf8Valid:   true,
 		},
 		{
-			ln:    "avalid_23name",
-			valid: true,
+			ln:          "avalid_23name",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			ln:    "Ava:lid_23name",
-			valid: false,
+			ln:          "Ava:lid_23name",
+			legacyValid: false,
+			utf8Valid:   true,
 		},
 		{
-			ln:    "a lid_23name",
-			valid: false,
+			ln:          "a lid_23name",
+			legacyValid: false,
+			utf8Valid:   true,
 		},
 		{
-			ln:    ":leading_colon",
-			valid: false,
+			ln:          ":leading_colon",
+			legacyValid: false,
+			utf8Valid:   true,
 		},
 		{
-			ln:    "colon:in:the:middle",
-			valid: false,
+			ln:          "colon:in:the:middle",
+			legacyValid: false,
+			utf8Valid:   true,
+		},
+		{
+			ln:          "a\xc5z",
+			legacyValid: false,
+			utf8Valid:   false,
 		},
 	}
 
 	for _, s := range scenarios {
-		if s.ln.IsValid() != s.valid {
-			t.Errorf("Expected %v for %q using IsValid method", s.valid, s.ln)
+		NameValidationScheme = LegacyValidation
+		if s.ln.IsValid() != s.legacyValid {
+			t.Errorf("Expected %v for %q using legacy IsValid method", s.legacyValid, s.ln)
+		}
+		if LabelNameRE.MatchString(string(s.ln)) != s.legacyValid {
+			t.Errorf("Expected %v for %q using legacy regexp match", s.legacyValid, s.ln)
 		}
-		if LabelNameRE.MatchString(string(s.ln)) != s.valid {
-			t.Errorf("Expected %v for %q using regexp match", s.valid, s.ln)
+		NameValidationScheme = UTF8Validation
+		if s.ln.IsValid() != s.utf8Valid {
+			t.Errorf("Expected %v for %q using UTF8 IsValid method", s.legacyValid, s.ln)
 		}
 	}
 }
diff --git a/model/labelset_test.go b/model/labelset_test.go
index a6f1212c..c008816a 100644
--- a/model/labelset_test.go
+++ b/model/labelset_test.go
@@ -52,6 +52,7 @@ func TestUnmarshalJSONLabelSet(t *testing.T) {
 	}
 }`
 
+	NameValidationScheme = LegacyValidation
 	err = json.Unmarshal([]byte(invalidlabelSetJSON), &c)
 	expectedErr := `"1nvalid_23name" is not a valid label name`
 	if err == nil || err.Error() != expectedErr {
diff --git a/model/metric.go b/model/metric.go
index f8c5eaba..9aa0b511 100644
--- a/model/metric.go
+++ b/model/metric.go
@@ -18,12 +18,39 @@ import (
 	"regexp"
 	"sort"
 	"strings"
+	"unicode/utf8"
 )
 
-// MetricNameRE is a regular expression matching valid metric
-// names. Note that the IsValidMetricName function performs the same
-// check but faster than a match with this regular expression.
-var MetricNameRE = regexp.MustCompile(`^[a-zA-Z_:][a-zA-Z0-9_:]*$`)
+// ValidationScheme is a Go enum for determining how metric and label names will
+// be validated by this library.
+type ValidationScheme int
+
+const (
+	// LegacyValidation is a setting that requirets that metric and label names
+	// conform to the original Prometheus character requirements described by
+	// MetricNameRE and LabelNameRE.
+	LegacyValidation ValidationScheme = iota
+
+	// UTF8Validation only requires that metric and label names be valid UTF8
+	// strings.
+	UTF8Validation
+)
+
+var (
+	// NameValidationScheme determines the method of name validation to be used by
+	// all calls to IsValidMetricName() and LabelName IsValid(). Setting UTF8 mode
+	// in isolation from other components that don't support UTF8 may result in
+	// bugs or other undefined behavior. This value is intended to be set by
+	// UTF8-aware binaries as part of their startup. To avoid need for locking,
+	// this value should be set once, ideally in an init(), before multiple
+	// goroutines are started.
+	NameValidationScheme = LegacyValidation
+
+	// MetricNameRE is a regular expression matching valid metric
+	// names. Note that the IsValidMetricName function performs the same
+	// check but faster than a match with this regular expression.
+	MetricNameRE = regexp.MustCompile(`^[a-zA-Z_:][a-zA-Z0-9_:]*$`)
+)
 
 // A Metric is similar to a LabelSet, but the key difference is that a Metric is
 // a singleton and refers to one and only one stream of samples.
@@ -84,10 +111,28 @@ func (m Metric) FastFingerprint() Fingerprint {
 	return LabelSet(m).FastFingerprint()
 }
 
-// IsValidMetricName returns true iff name matches the pattern of MetricNameRE.
+// IsValidMetricName returns true iff name matches the pattern of MetricNameRE
+// for legacy names, and iff it's valid UTF-8 if the UTF8Validation scheme is
+// selected.
+func IsValidMetricName(n LabelValue) bool {
+	switch NameValidationScheme {
+	case LegacyValidation:
+		return IsValidLegacyMetricName(n)
+	case UTF8Validation:
+		if len(n) == 0 {
+			return false
+		}
+		return utf8.ValidString(string(n))
+	default:
+		panic(fmt.Sprintf("Invalid name validation scheme requested: %d", NameValidationScheme))
+	}
+}
+
+// IsValidLegacyMetricName is similar to IsValidMetricName but always uses the
+// legacy validation scheme regardless of the value of NameValidationScheme.
 // This function, however, does not use MetricNameRE for the check but a much
 // faster hardcoded implementation.
-func IsValidMetricName(n LabelValue) bool {
+func IsValidLegacyMetricName(n LabelValue) bool {
 	if len(n) == 0 {
 		return false
 	}
diff --git a/model/metric_test.go b/model/metric_test.go
index cc4e27d0..60f82930 100644
--- a/model/metric_test.go
+++ b/model/metric_test.go
@@ -82,55 +82,75 @@ func BenchmarkMetric(b *testing.B) {
 	}
 }
 
-func TestMetricNameIsValid(t *testing.T) {
+func TestMetricNameIsLegacyValid(t *testing.T) {
 	scenarios := []struct {
-		mn    LabelValue
-		valid bool
+		mn          LabelValue
+		legacyValid bool
+		utf8Valid   bool
 	}{
 		{
-			mn:    "Avalid_23name",
-			valid: true,
+			mn:          "Avalid_23name",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			mn:    "_Avalid_23name",
-			valid: true,
+			mn:          "_Avalid_23name",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			mn:    "1valid_23name",
-			valid: false,
+			mn:          "1valid_23name",
+			legacyValid: false,
+			utf8Valid:   true,
 		},
 		{
-			mn:    "avalid_23name",
-			valid: true,
+			mn:          "avalid_23name",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			mn:    "Ava:lid_23name",
-			valid: true,
+			mn:          "Ava:lid_23name",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			mn:    "a lid_23name",
-			valid: false,
+			mn:          "a lid_23name",
+			legacyValid: false,
+			utf8Valid:   true,
 		},
 		{
-			mn:    ":leading_colon",
-			valid: true,
+			mn:          ":leading_colon",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			mn:    "colon:in:the:middle",
-			valid: true,
+			mn:          "colon:in:the:middle",
+			legacyValid: true,
+			utf8Valid:   true,
 		},
 		{
-			mn:    "",
-			valid: false,
+			mn:          "",
+			legacyValid: false,
+			utf8Valid:   false,
+		},
+		{
+			mn:          "a\xc5z",
+			legacyValid: false,
+			utf8Valid:   false,
 		},
 	}
 
 	for _, s := range scenarios {
-		if IsValidMetricName(s.mn) != s.valid {
-			t.Errorf("Expected %v for %q using IsValidMetricName function", s.valid, s.mn)
+		NameValidationScheme = LegacyValidation
+		if IsValidMetricName(s.mn) != s.legacyValid {
+			t.Errorf("Expected %v for %q using legacy IsValidMetricName method", s.legacyValid, s.mn)
+		}
+		if MetricNameRE.MatchString(string(s.mn)) != s.legacyValid {
+			t.Errorf("Expected %v for %q using regexp matching", s.legacyValid, s.mn)
 		}
-		if MetricNameRE.MatchString(string(s.mn)) != s.valid {
-			t.Errorf("Expected %v for %q using regexp matching", s.valid, s.mn)
+		NameValidationScheme = UTF8Validation
+		if IsValidMetricName(s.mn) != s.utf8Valid {
+			t.Errorf("Expected %v for %q using utf8 IsValidMetricName method", s.legacyValid, s.mn)
 		}
 	}
 }
diff --git a/model/silence_test.go b/model/silence_test.go
index e6b14116..0b5ad322 100644
--- a/model/silence_test.go
+++ b/model/silence_test.go
@@ -21,8 +21,9 @@ import (
 
 func TestMatcherValidate(t *testing.T) {
 	cases := []struct {
-		matcher *Matcher
-		err     string
+		matcher   *Matcher
+		legacyErr string
+		utf8Err   string
 	}{
 		{
 			matcher: &Matcher{
@@ -42,46 +43,74 @@ func TestMatcherValidate(t *testing.T) {
 				Name:  "name!",
 				Value: "value",
 			},
-			err: "invalid name",
+			legacyErr: "invalid name",
 		},
 		{
 			matcher: &Matcher{
 				Name:  "",
 				Value: "value",
 			},
-			err: "invalid name",
+			legacyErr: "invalid name",
+			utf8Err:   "invalid name",
 		},
 		{
 			matcher: &Matcher{
 				Name:  "name",
 				Value: "value\xff",
 			},
-			err: "invalid value",
+			legacyErr: "invalid value",
+			utf8Err:   "invalid value",
 		},
 		{
 			matcher: &Matcher{
 				Name:  "name",
 				Value: "",
 			},
-			err: "invalid value",
+			legacyErr: "invalid value",
+			utf8Err:   "invalid value",
+		},
+		{
+			matcher: &Matcher{
+				Name:  "a\xc5z",
+				Value: "",
+			},
+			legacyErr: "invalid name",
+			utf8Err:   "invalid name",
 		},
 	}
 
 	for i, c := range cases {
-		err := c.matcher.Validate()
-		if err == nil {
-			if c.err == "" {
+		NameValidationScheme = LegacyValidation
+		legacyErr := c.matcher.Validate()
+		NameValidationScheme = UTF8Validation
+		utf8Err := c.matcher.Validate()
+		if legacyErr == nil && utf8Err == nil {
+			if c.legacyErr == "" && c.utf8Err == "" {
 				continue
 			}
-			t.Errorf("%d. Expected error %q but got none", i, c.err)
+			if c.legacyErr != "" {
+				t.Errorf("%d. Expected error for legacy validation %q but got none", i, c.legacyErr)
+			}
+			if c.utf8Err != "" {
+				t.Errorf("%d. Expected error for utf8 validation %q but got none", i, c.utf8Err)
+			}
 			continue
 		}
-		if c.err == "" {
-			t.Errorf("%d. Expected no error but got %q", i, err)
-			continue
+		if legacyErr != nil {
+			if c.legacyErr == "" {
+				t.Errorf("%d. Expected no legacy validation error but got %q", i, legacyErr)
+			} else if !strings.Contains(legacyErr.Error(), c.legacyErr) {
+				t.Errorf("%d. Expected error to contain %q but got %q", i, c.legacyErr, legacyErr)
+			}
 		}
-		if !strings.Contains(err.Error(), c.err) {
-			t.Errorf("%d. Expected error to contain %q but got %q", i, c.err, err)
+		if utf8Err != nil {
+			if c.utf8Err == "" {
+				t.Errorf("%d. Expected no utf8 validation error but got %q", i, utf8Err)
+				continue
+			}
+			if !strings.Contains(utf8Err.Error(), c.utf8Err) {
+				t.Errorf("%d. Expected error to contain %q but got %q", i, c.utf8Err, utf8Err)
+			}
 		}
 	}
 }
@@ -219,6 +248,7 @@ func TestSilenceValidate(t *testing.T) {
 	}
 
 	for i, c := range cases {
+		NameValidationScheme = LegacyValidation
 		err := c.sil.Validate()
 		if err == nil {
 			if c.err == "" {