diff --git a/src/runtime/pprof/pprof_test.go b/src/runtime/pprof/pprof_test.go
index 704c0c516d..d9be00d030 100644
--- a/src/runtime/pprof/pprof_test.go
+++ b/src/runtime/pprof/pprof_test.go
@@ -116,6 +116,30 @@ func TestCPUProfileMultithreadMagnitude(t *testing.T) {
 		t.Skip("issue 35057 is only confirmed on Linux")
 	}
 
+	// Linux [5.9,5.16) has a kernel bug that can break CPU timers on newly
+	// created threads, breaking our CPU accounting.
+	major, minor, patch, err := linuxKernelVersion()
+	if err != nil {
+		t.Errorf("Error determining kernel version: %v", err)
+	}
+	t.Logf("Running on Linux %d.%d.%d", major, minor, patch)
+	defer func() {
+		if t.Failed() {
+			t.Logf("Failure of this test may indicate that your system suffers from a known Linux kernel bug fixed on newer kernels. See https://golang.org/issue/49065.")
+		}
+	}()
+
+	// Disable on affected builders to avoid flakiness, but otherwise keep
+	// it enabled to potentially warn users that they are on a broken
+	// kernel.
+	if testenv.Builder() != "" && (runtime.GOARCH == "386" || runtime.GOARCH == "amd64") {
+		have59 := major > 5 || (major == 5 && minor >= 9)
+		have516 := major > 5 || (major == 5 && minor >= 16)
+		if have59 && !have516 {
+			testenv.SkipFlaky(t, 49065)
+		}
+	}
+
 	// Run a workload in a single goroutine, then run copies of the same
 	// workload in several goroutines. For both the serial and parallel cases,
 	// the CPU time the process measures with its own profiler should match the
diff --git a/src/runtime/pprof/uname_linux_test.go b/src/runtime/pprof/uname_linux_test.go
new file mode 100644
index 0000000000..8374c83f74
--- /dev/null
+++ b/src/runtime/pprof/uname_linux_test.go
@@ -0,0 +1,61 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build linux
+
+package pprof
+
+import (
+	"fmt"
+	"regexp"
+	"strconv"
+	"syscall"
+)
+
+var versionRe = regexp.MustCompile(`^(\d+)(?:\.(\d+)(?:\.(\d+))).*$`)
+
+func linuxKernelVersion() (major, minor, patch int, err error) {
+	var uname syscall.Utsname
+	if err := syscall.Uname(&uname); err != nil {
+		return 0, 0, 0, err
+	}
+
+	buf := make([]byte, 0, len(uname.Release))
+	for _, b := range uname.Release {
+		if b == 0 {
+			break
+		}
+		buf = append(buf, byte(b))
+	}
+	rl := string(buf)
+
+	m := versionRe.FindStringSubmatch(rl)
+	if m == nil {
+		return 0, 0, 0, fmt.Errorf("error matching version number in %q", rl)
+	}
+
+	v, err := strconv.ParseInt(m[1], 10, 64)
+	if err != nil {
+		return 0, 0, 0, fmt.Errorf("error parsing major version %q in %s: %w", m[1], rl, err)
+	}
+	major = int(v)
+
+	if len(m) >= 3 {
+		v, err := strconv.ParseInt(m[2], 10, 64)
+		if err != nil {
+			return 0, 0, 0, fmt.Errorf("error parsing minor version %q in %s: %w", m[2], rl, err)
+		}
+		minor = int(v)
+	}
+
+	if len(m) >= 4 {
+		v, err := strconv.ParseInt(m[3], 10, 64)
+		if err != nil {
+			return 0, 0, 0, fmt.Errorf("error parsing patch version %q in %s: %w", m[3], rl, err)
+		}
+		patch = int(v)
+	}
+
+	return
+}
diff --git a/src/runtime/pprof/uname_other_test.go b/src/runtime/pprof/uname_other_test.go
new file mode 100644
index 0000000000..327640755b
--- /dev/null
+++ b/src/runtime/pprof/uname_other_test.go
@@ -0,0 +1,15 @@
+// Copyright 2021 The Go Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style
+// license that can be found in the LICENSE file.
+
+//go:build !linux
+
+package pprof
+
+import (
+	"errors"
+)
+
+func linuxKernelVersion() (major, minor, patch int, err error) {
+	return 0, 0, 0, errors.New("not running on linux")
+}