diff --git a/cmds/installd/file_parsing.h b/cmds/installd/file_parsing.h
index 3e2f815..88801ca 100644
--- a/cmds/installd/file_parsing.h
+++ b/cmds/installd/file_parsing.h
@@ -19,18 +19,14 @@
 
 #include <fstream>
 #include <functional>
-#include <string>
+#include <string_view>
+#include "android-base/unique_fd.h"
 
 namespace android {
 namespace installd {
 
-bool ParseFile(const std::string& strFile, std::function<bool (const std::string&)> parse) {
-    std::ifstream input_stream(strFile);
-
-    if (!input_stream.is_open()) {
-        return false;
-    }
-
+template<typename Func>
+bool ParseFile(std::istream& input_stream, Func parse) {
     while (!input_stream.eof()) {
         // Read the next line.
         std::string line;
@@ -54,6 +50,15 @@
     return true;
 }
 
+template<typename Func>
+bool ParseFile(std::string_view str_file, Func parse) {
+  std::ifstream ifs(str_file);
+  if (!ifs.is_open()) {
+    return false;
+  }
+  return ParseFile(ifs, parse);
+}
+
 }  // namespace installd
 }  // namespace android
 
diff --git a/cmds/installd/otapreopt.cpp b/cmds/installd/otapreopt.cpp
index ed31ad9..6aa32b8 100644
--- a/cmds/installd/otapreopt.cpp
+++ b/cmds/installd/otapreopt.cpp
@@ -26,6 +26,7 @@
 #include <sys/capability.h>
 #include <sys/prctl.h>
 #include <sys/stat.h>
+#include <sys/mman.h>
 
 #include <android-base/logging.h>
 #include <android-base/macros.h>
@@ -36,6 +37,7 @@
 #include <log/log.h>
 #include <private/android_filesystem_config.h>
 
+#include "android-base/file.h"
 #include "dexopt.h"
 #include "file_parsing.h"
 #include "globals.h"
@@ -195,38 +197,63 @@
         //   export NAME VALUE
         // For simplicity, don't respect string quotation. The values we are interested in can be
         // encoded without them.
-        // init.environ.rc and etc/classpath have the same format for
-        // environment variable exports and can be matched by the same regex.
+        //
+        // init.environ.rc and derive_classpath all have the same format for
+        // environment variable exports (since they are all meant to be read by
+        // init) and can be matched by the same regex.
+
+        std::regex export_regex("\\s*export\\s+(\\S+)\\s+(\\S+)");
+        auto parse_results = [&](auto& input) {
+          ParseFile(input, [&](const std::string& line) {
+              std::smatch export_match;
+              if (!std::regex_match(line, export_match, export_regex)) {
+                  return true;
+              }
+
+              if (export_match.size() != 3) {
+                  return true;
+              }
+
+              std::string name = export_match[1].str();
+              std::string value = export_match[2].str();
+
+              system_properties_.SetProperty(name, value);
+
+              return true;
+          });
+        };
+
         // TODO Just like with the system-properties above we really should have
         // common code between init and otapreopt to deal with reading these
         // things. See b/181182967
+        // There have been a variety of places the various env-vars have been
+        // over the years.  Expand or reduce this list as needed.
         static constexpr const char* kEnvironmentVariableSources[] = {
-                "/init.environ.rc", "/etc/classpath"
+                "/init.environ.rc",
         };
-
-        std::regex export_regex("\\s*export\\s+(\\S+)\\s+(\\S+)");
+        // First get everything from the static files.
         for (const char* env_vars_file : kEnvironmentVariableSources) {
-            bool parse_result = ParseFile(env_vars_file, [&](const std::string& line) {
-                std::smatch export_match;
-                if (!std::regex_match(line, export_match, export_regex)) {
-                    return true;
-                }
-
-                if (export_match.size() != 3) {
-                    return true;
-                }
-
-                std::string name = export_match[1].str();
-                std::string value = export_match[2].str();
-
-                system_properties_.SetProperty(name, value);
-
-                return true;
-            });
-            if (!parse_result) {
-                return false;
-            }
+          parse_results(env_vars_file);
         }
+
+        // Next get everything from derive_classpath, since we're already in the
+        // chroot it will get the new versions of any dependencies.
+        {
+          android::base::unique_fd fd(memfd_create("derive_classpath_temp", MFD_CLOEXEC));
+          if (!fd.ok()) {
+            LOG(ERROR) << "Unable to create fd for derive_classpath";
+            return false;
+          }
+          std::string memfd_file = StringPrintf("/proc/%d/fd/%d", getpid(), fd.get());
+          std::string error_msg;
+          if (!Exec({"/apex/com.android.sdkext/bin/derive_classpath", memfd_file}, &error_msg)) {
+            PLOG(ERROR) << "Running derive_classpath failed: " << error_msg;
+            return false;
+          }
+          std::ifstream ifs(memfd_file);
+          parse_results(ifs);
+        }
+
         if (system_properties_.GetProperty(kAndroidDataPathPropertyName) == nullptr) {
             return false;
         }
diff --git a/cmds/installd/otapreopt_chroot.cpp b/cmds/installd/otapreopt_chroot.cpp
index 83f01de..c62734a 100644
--- a/cmds/installd/otapreopt_chroot.cpp
+++ b/cmds/installd/otapreopt_chroot.cpp
@@ -275,6 +275,7 @@
     static constexpr const std::string_view kRequiredApexs[] = {
       "com.android.art",
       "com.android.runtime",
+      "com.android.sdkext",  // For derive_classpath
     };
     std::array<bool, arraysize(kRequiredApexs)> found_apexs{ false, false };
     DIR* apex_dir = opendir("/apex");