diff --git a/adb/adb.cpp b/adb/adb.cpp
index 39e71e5..0181daa 100644
--- a/adb/adb.cpp
+++ b/adb/adb.cpp
@@ -31,6 +31,8 @@
 #include <time.h>
 
 #include <chrono>
+#include <condition_variable>
+#include <mutex>
 #include <string>
 #include <thread>
 #include <vector>
@@ -48,6 +50,7 @@
 #include "adb_io.h"
 #include "adb_listeners.h"
 #include "adb_utils.h"
+#include "sysdeps/chrono.h"
 #include "transport.h"
 
 #if !ADB_HOST
@@ -313,19 +316,15 @@
     if (type == "bootloader") {
         D("setting connection_state to kCsBootloader");
         t->SetConnectionState(kCsBootloader);
-        update_transports();
     } else if (type == "device") {
         D("setting connection_state to kCsDevice");
         t->SetConnectionState(kCsDevice);
-        update_transports();
     } else if (type == "recovery") {
         D("setting connection_state to kCsRecovery");
         t->SetConnectionState(kCsRecovery);
-        update_transports();
     } else if (type == "sideload") {
         D("setting connection_state to kCsSideload");
         t->SetConnectionState(kCsSideload);
-        update_transports();
     } else {
         D("setting connection_state to kCsHost");
         t->SetConnectionState(kCsHost);
@@ -353,6 +352,8 @@
         send_auth_request(t);
     }
 #endif
+
+    update_transports();
 }
 
 void handle_packet(apacket *p, atransport *t)
@@ -1229,4 +1230,50 @@
       return ret - 1;
     return -1;
 }
+
+static auto& init_mutex = *new std::mutex();
+static auto& init_cv = *new std::condition_variable();
+static bool device_scan_complete = false;
+static bool transports_ready = false;
+
+void update_transport_status() {
+    bool result = iterate_transports([](const atransport* t) {
+        if (t->type == kTransportUsb && t->online != 1) {
+            return false;
+        }
+        return true;
+    });
+
+    D("update_transport_status: transports_ready = %s", result ? "true" : "false");
+
+    bool ready;
+
+    {
+        std::lock_guard<std::mutex> lock(init_mutex);
+        transports_ready = result;
+        ready = transports_ready && device_scan_complete;
+    }
+
+    if (ready) {
+        D("update_transport_status: notifying");
+        init_cv.notify_all();
+    }
+}
+
+void adb_notify_device_scan_complete() {
+    D("device scan complete");
+
+    {
+        std::lock_guard<std::mutex> lock(init_mutex);
+        device_scan_complete = true;
+    }
+
+    update_transport_status();
+}
+
+void adb_wait_for_device_initialization() {
+    std::unique_lock<std::mutex> lock(init_mutex);
+    init_cv.wait_for(lock, 3s, []() { return device_scan_complete && transports_ready; });
+}
+
 #endif  // ADB_HOST
diff --git a/adb/adb.h b/adb/adb.h
index e3675d8..d6b2b81 100644
--- a/adb/adb.h
+++ b/adb/adb.h
@@ -228,4 +228,18 @@
 
 void parse_banner(const std::string&, atransport* t);
 
+// On startup, the adb server needs to wait until all of the connected devices are ready.
+// To do this, we need to know when the scan has identified all of the potential new transports, and
+// when each transport becomes ready.
+// TODO: Do this for mDNS as well, instead of just USB?
+
+// We've found all of the transports we potentially care about.
+void adb_notify_device_scan_complete();
+
+// One or more transports have changed status, check to see if we're ready.
+void update_transport_status();
+
+// Wait until device scan has completed and every transport is ready, or a timeout elapses.
+void adb_wait_for_device_initialization();
+
 #endif
diff --git a/adb/adb_client.cpp b/adb/adb_client.cpp
index b656887..4f3ff25 100644
--- a/adb/adb_client.cpp
+++ b/adb/adb_client.cpp
@@ -28,12 +28,15 @@
 #include <sys/stat.h>
 #include <sys/types.h>
 
+#include <condition_variable>
+#include <mutex>
 #include <string>
 #include <thread>
 #include <vector>
 
 #include <android-base/stringprintf.h>
 #include <android-base/strings.h>
+#include <android-base/thread_annotations.h>
 #include <cutils/sockets.h>
 
 #include "adb_io.h"
@@ -177,9 +180,8 @@
         } else {
             fprintf(stderr, "* daemon started successfully\n");
         }
-        // Give the server some time to start properly and detect devices.
-        std::this_thread::sleep_for(3s);
-        // fall through to _adb_connect
+        // The server will wait until it detects all of its connected devices before acking.
+        // Fall through to _adb_connect.
     } else {
         // If a server is already running, check its version matches.
         int version = ADB_SERVER_VERSION - 1;
diff --git a/adb/client/main.cpp b/adb/client/main.cpp
index 606203c..fe5099c 100644
--- a/adb/client/main.cpp
+++ b/adb/client/main.cpp
@@ -156,33 +156,38 @@
         }
 #endif
 
-        // Inform our parent that we are up and running.
+        // Wait for the USB scan to complete before notifying the parent that we're up.
+        // We need to perform this in a thread, because we would otherwise block the event loop.
+        std::thread notify_thread([ack_reply_fd]() {
+            adb_wait_for_device_initialization();
 
-        // Any error output written to stderr now goes to adb.log. We could
-        // keep around a copy of the stderr fd and use that to write any errors
-        // encountered by the following code, but that is probably overkill.
+            // Any error output written to stderr now goes to adb.log. We could
+            // keep around a copy of the stderr fd and use that to write any errors
+            // encountered by the following code, but that is probably overkill.
 #if defined(_WIN32)
-        const HANDLE ack_reply_handle = cast_int_to_handle(ack_reply_fd);
-        const CHAR ack[] = "OK\n";
-        const DWORD bytes_to_write = arraysize(ack) - 1;
-        DWORD written = 0;
-        if (!WriteFile(ack_reply_handle, ack, bytes_to_write, &written, NULL)) {
-            fatal("adb: cannot write ACK to handle 0x%p: %s", ack_reply_handle,
-                  android::base::SystemErrorCodeToString(GetLastError()).c_str());
-        }
-        if (written != bytes_to_write) {
-            fatal("adb: cannot write %lu bytes of ACK: only wrote %lu bytes",
-                  bytes_to_write, written);
-        }
-        CloseHandle(ack_reply_handle);
+            const HANDLE ack_reply_handle = cast_int_to_handle(ack_reply_fd);
+            const CHAR ack[] = "OK\n";
+            const DWORD bytes_to_write = arraysize(ack) - 1;
+            DWORD written = 0;
+            if (!WriteFile(ack_reply_handle, ack, bytes_to_write, &written, NULL)) {
+                fatal("adb: cannot write ACK to handle 0x%p: %s", ack_reply_handle,
+                      android::base::SystemErrorCodeToString(GetLastError()).c_str());
+            }
+            if (written != bytes_to_write) {
+                fatal("adb: cannot write %lu bytes of ACK: only wrote %lu bytes", bytes_to_write,
+                      written);
+            }
+            CloseHandle(ack_reply_handle);
 #else
-        // TODO(danalbert): Can't use SendOkay because we're sending "OK\n", not
-        // "OKAY".
-        if (!android::base::WriteStringToFd("OK\n", ack_reply_fd)) {
-            fatal_errno("error writing ACK to fd %d", ack_reply_fd);
-        }
-        unix_close(ack_reply_fd);
+            // TODO(danalbert): Can't use SendOkay because we're sending "OK\n", not
+            // "OKAY".
+            if (!android::base::WriteStringToFd("OK\n", ack_reply_fd)) {
+                fatal_errno("error writing ACK to fd %d", ack_reply_fd);
+            }
+            unix_close(ack_reply_fd);
 #endif
+        });
+        notify_thread.detach();
     }
 
     D("Event loop starting");
diff --git a/adb/client/usb_libusb.cpp b/adb/client/usb_libusb.cpp
index d39884a..20610ee 100644
--- a/adb/client/usb_libusb.cpp
+++ b/adb/client/usb_libusb.cpp
@@ -352,6 +352,8 @@
         }
         libusb_free_device_list(list, 1);
 
+        adb_notify_device_scan_complete();
+
         std::this_thread::sleep_for(500ms);
     }
 }
diff --git a/adb/transport.cpp b/adb/transport.cpp
index cc8c162..20de642 100644
--- a/adb/transport.cpp
+++ b/adb/transport.cpp
@@ -400,8 +400,27 @@
     return &tracker->socket;
 }
 
+// Check if all of the USB transports are connected.
+bool iterate_transports(std::function<bool(const atransport*)> fn) {
+    std::lock_guard<std::mutex> lock(transport_lock);
+    for (const auto& t : transport_list) {
+        if (!fn(t)) {
+            return false;
+        }
+    }
+    for (const auto& t : pending_list) {
+        if (!fn(t)) {
+            return false;
+        }
+    }
+    return true;
+}
+
 // Call this function each time the transport list has changed.
 void update_transports() {
+    update_transport_status();
+
+    // Notify `adb track-devices` clients.
     std::string transports = list_transports(false);
 
     device_tracker* tracker = device_tracker_list;
diff --git a/adb/transport.h b/adb/transport.h
index 8c15d66..e129355 100644
--- a/adb/transport.h
+++ b/adb/transport.h
@@ -198,6 +198,10 @@
 void kick_transport(atransport* t);
 void update_transports(void);
 
+// Iterates across all of the current and pending transports.
+// Stops iteration and returns false if fn returns false, otherwise returns true.
+bool iterate_transports(std::function<bool(const atransport*)> fn);
+
 void init_transport_registration(void);
 void init_mdns_transport_discovery(void);
 std::string list_transports(bool long_listing);