diff --git a/all/build.gradle b/all/build.gradle
index 22b50bd594..62d648a847 100644
--- a/all/build.gradle
+++ b/all/build.gradle
@@ -3,6 +3,13 @@ description = "gRPC: All"
 // Make sure that no transitive dependencies are included.
 configurations.compile.transitive = false
 
+for (subproject in rootProject.subprojects) {
+    if (subproject == project) {
+        continue
+    }
+    evaluationDependsOn(subproject.path)
+}
+
 dependencies {
     compile project(':grpc-auth'),
             project(':grpc-core'),
@@ -22,3 +29,15 @@ jar {
     }
 }
 
+javadoc {
+    classpath = files(rootProject.subprojects.collect { subproject ->
+        subproject.javadoc.classpath
+    })
+    for (subproject in rootProject.subprojects) {
+        if (subproject == project) {
+            continue;
+        }
+        source subproject.javadoc.source
+        options.links subproject.javadoc.options.links.toArray(new String[0])
+    }
+}
diff --git a/build.gradle b/build.gradle
index 6442429e58..546d3c2b60 100644
--- a/build.gradle
+++ b/build.gradle
@@ -32,7 +32,10 @@ subprojects {
         it.options.encoding = "UTF-8"
     }
 
-    javadoc.options.encoding = "UTF-8"
+    javadoc.options {
+        encoding = 'UTF-8'
+        links 'https://docs.oracle.com/javase/8/docs/api/'
+    }
 
     ext {
         libraries = [
diff --git a/netty/build.gradle b/netty/build.gradle
index 8c6eedc3cb..ddf5a6332a 100644
--- a/netty/build.gradle
+++ b/netty/build.gradle
@@ -7,3 +7,5 @@ dependencies {
     // Tests depend on base class defined by core module.
     testCompile project(':grpc-core').sourceSets.test.output
 }
+
+javadoc.options.links 'https://netty.io/4.1/api/'
diff --git a/okhttp/build.gradle b/okhttp/build.gradle
index 28a0f2b4e2..af8ca0e272 100644
--- a/okhttp/build.gradle
+++ b/okhttp/build.gradle
@@ -15,3 +15,6 @@ dependencies {
 animalsniffer {
     signature = "org.codehaus.mojo.signature:java16:+@signature"
 }
+
+javadoc.exclude 'com/squareup/**'
+javadoc.options.links 'http://square.github.io/okhttp/javadoc/'
diff --git a/stub/build.gradle b/stub/build.gradle
index d242393c89..8f15c28ed3 100644
--- a/stub/build.gradle
+++ b/stub/build.gradle
@@ -10,4 +10,6 @@ dependencies {
 // Configure the animal sniffer plugin
 animalsniffer {
     signature = "org.codehaus.mojo.signature:java16:+@signature"
-}
\ No newline at end of file
+}
+
+javadoc.options.links 'http://docs.guava-libraries.googlecode.com/git-history/release/javadoc/'