diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
index 5b63ff4fe44..149dc49d87e 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/SpannerOptions.java
@@ -34,6 +34,8 @@
 import com.google.api.gax.tracing.ApiTracerFactory;
 import com.google.api.gax.tracing.BaseApiTracerFactory;
 import com.google.api.gax.tracing.OpencensusTracerFactory;
+import com.google.auth.oauth2.AccessToken;
+import com.google.auth.oauth2.GoogleCredentials;
 import com.google.cloud.NoCredentials;
 import com.google.cloud.ServiceDefaults;
 import com.google.cloud.ServiceOptions;
@@ -79,8 +81,11 @@
 import java.io.IOException;
 import java.net.MalformedURLException;
 import java.net.URL;
+import java.nio.file.Files;
+import java.nio.file.Paths;
 import java.time.Duration;
 import java.util.ArrayList;
+import java.util.Base64;
 import java.util.HashMap;
 import java.util.List;
 import java.util.Map;
@@ -92,6 +97,7 @@
 import java.util.concurrent.ThreadFactory;
 import java.util.concurrent.TimeUnit;
 import java.util.concurrent.atomic.AtomicInteger;
+import java.util.regex.Pattern;
 import javax.annotation.Nonnull;
 import javax.annotation.Nullable;
 import javax.annotation.concurrent.GuardedBy;
@@ -110,6 +116,11 @@ public class SpannerOptions extends ServiceOptions<Spanner, SpannerOptions> {
 
   private static final String API_SHORT_NAME = "Spanner";
   private static final String DEFAULT_HOST = "https://spanner.googleapis.com";
+  private static final String CLOUD_SPANNER_HOST_FORMAT = ".*\\.googleapis\\.com.*";
+
+  @VisibleForTesting
+  static final Pattern CLOUD_SPANNER_HOST_PATTERN = Pattern.compile(CLOUD_SPANNER_HOST_FORMAT);
+
   private static final ImmutableSet<String> SCOPES =
       ImmutableSet.of(
           "https://www.googleapis.com/auth/spanner.admin",
@@ -799,6 +810,18 @@ protected SpannerOptions(Builder builder) {
     enableBuiltInMetrics = builder.enableBuiltInMetrics;
     enableEndToEndTracing = builder.enableEndToEndTracing;
     monitoringHost = builder.monitoringHost;
+    String externalHostTokenPath = System.getenv("SPANNER_EXTERNAL_HOST_AUTH_TOKEN");
+    if (builder.isExternalHost && builder.emulatorHost == null && externalHostTokenPath != null) {
+      String token;
+      try {
+        token =
+            Base64.getEncoder()
+                .encodeToString(Files.readAllBytes(Paths.get(externalHostTokenPath)));
+      } catch (IOException e) {
+        throw SpannerExceptionFactory.newSpannerException(e);
+      }
+      credentials = new GoogleCredentials(new AccessToken(token, null));
+    }
   }
 
   /**
@@ -967,6 +990,7 @@ public static class Builder
     private boolean enableBuiltInMetrics = SpannerOptions.environment.isEnableBuiltInMetrics();
     private String monitoringHost = SpannerOptions.environment.getMonitoringHost();
     private SslContext mTLSContext = null;
+    private boolean isExternalHost = false;
 
     private static String createCustomClientLibToken(String token) {
       return token + " " + ServiceOptions.getGoogApiClientLibName();
@@ -1459,6 +1483,9 @@ public Builder setDecodeMode(DecodeMode decodeMode) {
     @Override
     public Builder setHost(String host) {
       super.setHost(host);
+      if (this.emulatorHost == null && !CLOUD_SPANNER_HOST_PATTERN.matcher(host).matches()) {
+        this.isExternalHost = true;
+      }
       // Setting a host should override any SPANNER_EMULATOR_HOST setting.
       setEmulatorHost(null);
       return this;
diff --git a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/SpannerPool.java b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/SpannerPool.java
index 9558947156c..dedc2a2deed 100644
--- a/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/SpannerPool.java
+++ b/google-cloud-spanner/src/main/java/com/google/cloud/spanner/connection/SpannerPool.java
@@ -407,6 +407,9 @@ Spanner createSpanner(SpannerPoolKey key, ConnectionOptions options) {
     if (options.getConfigurator() != null) {
       options.getConfigurator().configure(builder);
     }
+    if (options.usesEmulator()) {
+      builder.setEmulatorHost(key.host);
+    }
     return builder.build().getService();
   }
 
diff --git a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerOptionsTest.java b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerOptionsTest.java
index 70482c0ffdd..72bbdf82eae 100644
--- a/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerOptionsTest.java
+++ b/google-cloud-spanner/src/test/java/com/google/cloud/spanner/SpannerOptionsTest.java
@@ -16,6 +16,7 @@
 
 package com.google.cloud.spanner;
 
+import static com.google.cloud.spanner.SpannerOptions.CLOUD_SPANNER_HOST_PATTERN;
 import static com.google.common.truth.Truth.assertThat;
 import static org.hamcrest.CoreMatchers.is;
 import static org.hamcrest.MatcherAssert.assertThat;
@@ -1164,4 +1165,12 @@ public void checkGlobalOpenTelemetryWhenNotInjected() {
             .build();
     assertEquals(GlobalOpenTelemetry.get(), options.getOpenTelemetry());
   }
+
+  @Test
+  public void testCloudSpannerHostPattern() {
+    assertTrue(CLOUD_SPANNER_HOST_PATTERN.matcher("https://spanner.googleapis.com").matches());
+    assertTrue(
+        CLOUD_SPANNER_HOST_PATTERN.matcher("https://product-area.googleapis.com:443").matches());
+    assertFalse(CLOUD_SPANNER_HOST_PATTERN.matcher("https://some-company.com:443").matches());
+  }
 }