diff --git a/ssl/test/runner/common.go b/ssl/test/runner/common.go
index 2b7e29b..f578631 100644
--- a/ssl/test/runner/common.go
+++ b/ssl/test/runner/common.go
@@ -762,6 +762,10 @@
 	// shutdown. Records from the peer received after close_notify is sent
 	// are not discard.
 	ExpectCloseNotify bool
+
+	// SendLargeRecords, if true, allows outgoing records to be sent
+	// arbitrarily large.
+	SendLargeRecords bool
 }
 
 func (c *Config) serverInit() {
diff --git a/ssl/test/runner/conn.go b/ssl/test/runner/conn.go
index 42bc840..1b8700c 100644
--- a/ssl/test/runner/conn.go
+++ b/ssl/test/runner/conn.go
@@ -876,7 +876,7 @@
 	isClientHello := typ == recordTypeHandshake && len(data) > 0 && data[0] == typeClientHello
 	for len(data) > 0 || first {
 		m := len(data)
-		if m > maxPlaintext {
+		if m > maxPlaintext && !c.config.Bugs.SendLargeRecords {
 			m = maxPlaintext
 		}
 		if typ == recordTypeHandshake && c.config.Bugs.MaxHandshakeRecordLength > 0 && m > c.config.Bugs.MaxHandshakeRecordLength {
diff --git a/ssl/test/runner/runner.go b/ssl/test/runner/runner.go
index 7ada5f1..d085913 100644
--- a/ssl/test/runner/runner.go
+++ b/ssl/test/runner/runner.go
@@ -1984,6 +1984,47 @@
 				})
 			}
 		}
+
+		// Ensure both TLS and DTLS accept their maximum record sizes.
+		testCases = append(testCases, testCase{
+			name: suite.name + "-LargeRecord",
+			config: Config{
+				CipherSuites:         []uint16{suite.id},
+				Certificates:         []Certificate{cert},
+				PreSharedKey:         []byte(psk),
+				PreSharedKeyIdentity: pskIdentity,
+			},
+			flags:      flags,
+			messageLen: maxPlaintext,
+		})
+		testCases = append(testCases, testCase{
+			name: suite.name + "-LargeRecord-Extra",
+			config: Config{
+				CipherSuites:         []uint16{suite.id},
+				Certificates:         []Certificate{cert},
+				PreSharedKey:         []byte(psk),
+				PreSharedKeyIdentity: pskIdentity,
+				Bugs: ProtocolBugs{
+					SendLargeRecords: true,
+				},
+			},
+			flags:      append(flags, "-microsoft-big-sslv3-buffer"),
+			messageLen: maxPlaintext + 16384,
+		})
+		if isDTLSCipher(suite.name) {
+			testCases = append(testCases, testCase{
+				protocol: dtls,
+				name:     suite.name + "-LargeRecord-DTLS",
+				config: Config{
+					CipherSuites:         []uint16{suite.id},
+					Certificates:         []Certificate{cert},
+					PreSharedKey:         []byte(psk),
+					PreSharedKeyIdentity: pskIdentity,
+				},
+				flags:      flags,
+				messageLen: maxPlaintext,
+			})
+		}
 	}
 
 	testCases = append(testCases, testCase{