diff --git a/fs_mgr/libfs_avb/avb_util.cpp b/fs_mgr/libfs_avb/avb_util.cpp
index fa9080e..80fa5c4 100644
--- a/fs_mgr/libfs_avb/avb_util.cpp
+++ b/fs_mgr/libfs_avb/avb_util.cpp
@@ -34,6 +34,19 @@
 namespace android {
 namespace fs_mgr {
 
+std::string GetAvbPropertyDescriptor(const std::string& key,
+                                     const std::vector<VBMetaData>& vbmeta_images) {
+    size_t value_size;
+    for (const auto& vbmeta : vbmeta_images) {
+        const char* value = avb_property_lookup(vbmeta.data(), vbmeta.size(), key.data(),
+                                                key.size(), &value_size);
+        if (value != nullptr) {
+            return {value, value_size};
+        }
+    }
+    return "";
+}
+
 // Constructs dm-verity arguments for sending DM_TABLE_LOAD ioctl to kernel.
 // See the following link for more details:
 // https://gitlab.com/cryptsetup/cryptsetup/wikis/DMVerity
diff --git a/fs_mgr/libfs_avb/avb_util.h b/fs_mgr/libfs_avb/avb_util.h
index 9babd88..5f413e3 100644
--- a/fs_mgr/libfs_avb/avb_util.h
+++ b/fs_mgr/libfs_avb/avb_util.h
@@ -37,6 +37,9 @@
         : partition_name(chain_partition_name), public_key_blob(chain_public_key_blob) {}
 };
 
+std::string GetAvbPropertyDescriptor(const std::string& key,
+                                     const std::vector<VBMetaData>& vbmeta_images);
+
 // AvbHashtreeDescriptor to dm-verity table setup.
 std::unique_ptr<FsAvbHashtreeDescriptor> GetHashtreeDescriptor(
         const std::string& partition_name, const std::vector<VBMetaData>& vbmeta_images);
diff --git a/fs_mgr/libfs_avb/fs_avb.cpp b/fs_mgr/libfs_avb/fs_avb.cpp
index 938e149..02902f0 100644
--- a/fs_mgr/libfs_avb/fs_avb.cpp
+++ b/fs_mgr/libfs_avb/fs_avb.cpp
@@ -263,6 +263,69 @@
     return avb_handle;
 }
 
+AvbUniquePtr AvbHandle::LoadAndVerifyVbmeta(const FstabEntry& fstab_entry) {
+    if (fstab_entry.avb_key.empty()) {
+        LERROR << "avb_key=/path/to/key is missing for " << fstab_entry.mount_point;
+        return nullptr;
+    }
+
+    // Binds allow_verification_error and rollback_protection to device unlock state.
+    bool allow_verification_error = IsDeviceUnlocked();
+    bool rollback_protection = !allow_verification_error;
+
+    std::string expected_key_blob;
+    if (!ReadFileToString(fstab_entry.avb_key, &expected_key_blob)) {
+        if (!allow_verification_error) {
+            LERROR << "Failed to load avb_key: " << fstab_entry.avb_key
+                   << " for mount point: " << fstab_entry.mount_point;
+            return nullptr;
+        }
+        LWARNING << "Allowing no expected key blob when verification error is permitted";
+        expected_key_blob.clear();
+    }
+
+    bool verification_disabled = false;
+    VBMetaVerifyResult verify_result = VBMetaVerifyResult::kError;
+    std::unique_ptr<VBMetaData> vbmeta = LoadAndVerifyVbmetaByPath(
+            fstab_entry.blk_device, "" /* partition_name, no need for a standalone path */,
+            expected_key_blob, allow_verification_error, rollback_protection,
+            false /* not is_chained_vbmeta */, nullptr /* out_public_key_data */,
+            &verification_disabled, &verify_result);
+
+    if (!vbmeta) {
+        LERROR << "Failed to load vbmeta: " << fstab_entry.blk_device;
+        return nullptr;
+    }
+
+    AvbUniquePtr avb_handle(new AvbHandle());
+    if (!avb_handle) {
+        LERROR << "Failed to allocate AvbHandle";
+        return nullptr;
+    }
+    avb_handle->vbmeta_images_.emplace_back(std::move(*vbmeta));
+
+    switch (verify_result) {
+        case VBMetaVerifyResult::kSuccess:
+            avb_handle->status_ = AvbHandleStatus::kSuccess;
+            break;
+        case VBMetaVerifyResult::kErrorVerification:
+            avb_handle->status_ = AvbHandleStatus::kVerificationError;
+            break;
+        default:
+            LERROR << "LoadAndVerifyVbmetaByPath failed, result: " << verify_result;
+            return nullptr;
+    }
+
+    if (verification_disabled) {
+        LINFO << "AVB verification disabled on: " << fstab_entry.mount_point;
+        avb_handle->status_ = AvbHandleStatus::kVerificationDisabled;
+    }
+
+    LINFO << "Returning avb_handle for '" << fstab_entry.mount_point
+          << "' with status: " << avb_handle->status_;
+    return avb_handle;
+}
+
 AvbUniquePtr AvbHandle::LoadAndVerifyVbmeta() {
     // Loads inline vbmeta images, starting from /vbmeta.
     return LoadAndVerifyVbmeta("vbmeta", fs_mgr_get_slot_suffix(), fs_mgr_get_other_slot_suffix(),
@@ -358,52 +421,12 @@
 
 AvbHashtreeResult AvbHandle::SetUpStandaloneAvbHashtree(FstabEntry* fstab_entry,
                                                         bool wait_for_verity_dev) {
-    if (fstab_entry->avb_key.empty()) {
-        LERROR << "avb_key=/path/to/key is missing for " << fstab_entry->mount_point;
+    auto avb_handle = LoadAndVerifyVbmeta(*fstab_entry);
+    if (!avb_handle) {
         return AvbHashtreeResult::kFail;
     }
 
-    // Binds allow_verification_error and rollback_protection to device unlock state.
-    bool allow_verification_error = IsDeviceUnlocked();
-    bool rollback_protection = !allow_verification_error;
-
-    std::string expected_key_blob;
-    if (!ReadFileToString(fstab_entry->avb_key, &expected_key_blob)) {
-        if (!allow_verification_error) {
-            LERROR << "Failed to load avb_key: " << fstab_entry->avb_key
-                   << " for mount point: " << fstab_entry->mount_point;
-            return AvbHashtreeResult::kFail;
-        }
-        LWARNING << "Allowing no expected key blob when verification error is permitted";
-        expected_key_blob.clear();
-    }
-
-    bool verification_disabled = false;
-    std::unique_ptr<VBMetaData> vbmeta = LoadAndVerifyVbmetaByPath(
-            fstab_entry->blk_device, "" /* partition_name, no need for a standalone path */,
-            expected_key_blob, allow_verification_error, rollback_protection,
-            false /* not is_chained_vbmeta */, nullptr /* out_public_key_data */,
-            &verification_disabled, nullptr /* out_verify_result */);
-
-    if (!vbmeta) {
-        LERROR << "Failed to load vbmeta: " << fstab_entry->blk_device;
-        return AvbHashtreeResult::kFail;
-    }
-
-    if (verification_disabled) {
-        LINFO << "AVB verification disabled on: " << fstab_entry->mount_point;
-        return AvbHashtreeResult::kDisabled;
-    }
-
-    // Puts the vbmeta into a vector, for LoadAvbHashtreeToEnableVerity() to use.
-    std::vector<VBMetaData> vbmeta_images;
-    vbmeta_images.emplace_back(std::move(*vbmeta));
-    if (!LoadAvbHashtreeToEnableVerity(fstab_entry, wait_for_verity_dev, vbmeta_images,
-                                       fs_mgr_get_slot_suffix(), fs_mgr_get_other_slot_suffix())) {
-        return AvbHashtreeResult::kFail;
-    }
-
-    return AvbHashtreeResult::kSuccess;
+    return avb_handle->SetUpAvbHashtree(fstab_entry, wait_for_verity_dev);
 }
 
 AvbHashtreeResult AvbHandle::SetUpAvbHashtree(FstabEntry* fstab_entry, bool wait_for_verity_dev) {
@@ -425,5 +448,19 @@
     return AvbHashtreeResult::kSuccess;
 }
 
+std::string AvbHandle::GetSecurityPatchLevel(const FstabEntry& fstab_entry) const {
+    if (vbmeta_images_.size() < 1) {
+        return "";
+    }
+    std::string avb_partition_name = DeriveAvbPartitionName(fstab_entry, fs_mgr_get_slot_suffix(),
+                                                            fs_mgr_get_other_slot_suffix());
+    auto avb_prop_name = "com.android.build." + avb_partition_name + ".security_patch";
+    return GetAvbPropertyDescriptor(avb_prop_name, vbmeta_images_);
+}
+
+bool AvbHandle::IsDeviceUnlocked() {
+    return android::fs_mgr::IsDeviceUnlocked();
+}
+
 }  // namespace fs_mgr
 }  // namespace android
diff --git a/fs_mgr/libfs_avb/include/fs_avb/fs_avb.h b/fs_mgr/libfs_avb/include/fs_avb/fs_avb.h
index d026722..7127fa6 100644
--- a/fs_mgr/libfs_avb/include/fs_avb/fs_avb.h
+++ b/fs_mgr/libfs_avb/include/fs_avb/fs_avb.h
@@ -85,6 +85,8 @@
     // TODO(bowgotsai): remove Open() and switch to LoadAndVerifyVbmeta().
     static AvbUniquePtr Open();                 // loads inline vbmeta, via libavb.
     static AvbUniquePtr LoadAndVerifyVbmeta();  // loads inline vbmeta.
+    static AvbUniquePtr LoadAndVerifyVbmeta(
+            const FstabEntry& fstab_entry);     // loads offline vbmeta.
     static AvbUniquePtr LoadAndVerifyVbmeta(    // loads offline vbmeta.
             const std::string& partition_name, const std::string& ab_suffix,
             const std::string& ab_other_suffix, const std::string& expected_public_key,
@@ -108,6 +110,10 @@
     static AvbHashtreeResult SetUpStandaloneAvbHashtree(FstabEntry* fstab_entry,
                                                         bool wait_for_verity_dev = true);
 
+    static bool IsDeviceUnlocked();
+
+    std::string GetSecurityPatchLevel(const FstabEntry& fstab_entry) const;
+
     const std::string& avb_version() const { return avb_version_; }
     const VBMetaInfo& vbmeta_info() const { return vbmeta_info_; }
     AvbHandleStatus status() const { return status_; }
diff --git a/fs_mgr/libfs_avb/tests/avb_util_test.cpp b/fs_mgr/libfs_avb/tests/avb_util_test.cpp
index 835410f..e4213b7 100644
--- a/fs_mgr/libfs_avb/tests/avb_util_test.cpp
+++ b/fs_mgr/libfs_avb/tests/avb_util_test.cpp
@@ -30,6 +30,7 @@
 using android::fs_mgr::DeriveAvbPartitionName;
 using android::fs_mgr::FstabEntry;
 using android::fs_mgr::GetAvbFooter;
+using android::fs_mgr::GetAvbPropertyDescriptor;
 using android::fs_mgr::GetChainPartitionInfo;
 using android::fs_mgr::GetTotalSize;
 using android::fs_mgr::LoadAndVerifyVbmetaByPartition;
@@ -268,6 +269,67 @@
     EXPECT_EQ(nullptr, footer);
 }
 
+TEST_F(AvbUtilTest, GetAvbPropertyDescriptor_Basic) {
+    // Makes a vbmeta.img with some properties.
+    GenerateVBMetaImage("vbmeta.img", "SHA256_RSA4096", 0, data_dir_.Append("testkey_rsa4096.pem"),
+                        {}, /* include_descriptor_image_paths */
+                        {}, /* chain_partitions */
+                        "--prop foo:android "
+                        "--prop bar:treble "
+                        "--internal_release_string \"unit test\" ");
+    auto vbmeta = LoadVBMetaData("vbmeta.img");
+
+    // Puts the vbmeta into a vector, for GetAvbPropertyDescriptor to use.
+    std::vector<VBMetaData> vbmeta_images;
+    vbmeta_images.emplace_back(std::move(vbmeta));
+
+    EXPECT_EQ("android", GetAvbPropertyDescriptor("foo", vbmeta_images));
+    EXPECT_EQ("treble", GetAvbPropertyDescriptor("bar", vbmeta_images));
+    EXPECT_EQ("", GetAvbPropertyDescriptor("non-existent", vbmeta_images));
+}
+
+TEST_F(AvbUtilTest, GetAvbPropertyDescriptor_SecurityPatchLevel) {
+    // Generates a raw boot.img
+    const size_t boot_image_size = 5 * 1024 * 1024;
+    const size_t boot_partition_size = 10 * 1024 * 1024;
+    base::FilePath boot_path = GenerateImage("boot.img", boot_image_size);
+    // Adds AVB Hash Footer.
+    AddAvbFooter(boot_path, "hash", "boot", boot_partition_size, "SHA256_RSA2048", 10,
+                 data_dir_.Append("testkey_rsa2048.pem"), "d00df00d",
+                 "--internal_release_string \"unit test\"");
+
+    // Generates a raw system.img, use a smaller size to speed-up unit test.
+    const size_t system_image_size = 10 * 1024 * 1024;
+    const size_t system_partition_size = 15 * 1024 * 1024;
+    base::FilePath system_path = GenerateImage("system.img", system_image_size);
+    // Adds AVB Hashtree Footer.
+    AddAvbFooter(system_path, "hashtree", "system", system_partition_size, "SHA512_RSA4096", 20,
+                 data_dir_.Append("testkey_rsa4096.pem"), "d00df00d",
+                 "--prop com.android.build.system.security_patch:2019-04-05 "
+                 "--internal_release_string \"unit test\"");
+
+    // Generates chain partition descriptors.
+    base::FilePath rsa4096_public_key =
+            ExtractPublicKeyAvb(data_dir_.Append("testkey_rsa4096.pem"));
+
+    // Makes a vbmeta.img including the 'system' chained descriptor.
+    GenerateVBMetaImage("vbmeta.img", "SHA256_RSA4096", 0, data_dir_.Append("testkey_rsa4096.pem"),
+                        {boot_path},                         /* include_descriptor_image_paths */
+                        {{"system", 3, rsa4096_public_key}}, /* chain_partitions */
+                        "--internal_release_string \"unit test\"");
+
+    auto vbmeta = LoadVBMetaData("vbmeta.img");
+    auto system_vbmeta = ExtractAndLoadVBMetaData(system_path, "system-vbmeta.img");
+
+    // Puts the vbmeta into a vector, for GetAvbPropertyDescriptor to use.
+    std::vector<VBMetaData> vbmeta_images;
+    vbmeta_images.emplace_back(std::move(vbmeta));
+    vbmeta_images.emplace_back(std::move(system_vbmeta));
+
+    EXPECT_EQ("2019-04-05",
+              GetAvbPropertyDescriptor("com.android.build.system.security_patch", vbmeta_images));
+}
+
 TEST_F(AvbUtilTest, GetVBMetaHeader) {
     // Generates a raw boot.img
     const size_t image_size = 5 * 1024 * 1024;
diff --git a/fs_mgr/libfs_avb/tests/fs_avb_device_test.cpp b/fs_mgr/libfs_avb/tests/fs_avb_device_test.cpp
index fc4eb5f..4631330 100644
--- a/fs_mgr/libfs_avb/tests/fs_avb_device_test.cpp
+++ b/fs_mgr/libfs_avb/tests/fs_avb_device_test.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <android-base/properties.h>
+#include <fs_avb/fs_avb.h>
 #include <fs_avb/fs_avb_util.h>
 #include <fstab/fstab.h>
 #include <gtest/gtest.h>
@@ -22,6 +23,8 @@
 #include <sys/types.h>
 #include <unistd.h>
 
+using android::fs_mgr::AvbHandle;
+using android::fs_mgr::AvbHandleStatus;
 using android::fs_mgr::Fstab;
 using android::fs_mgr::FstabEntry;
 using android::fs_mgr::VBMetaData;
@@ -31,7 +34,7 @@
 
 // system vbmeta might not be at the end of /system when dynamic partition is
 // enabled. Therefore, disable it by default.
-TEST(PublicFsAvbDeviceTest, DISABLED_LoadAndVerifyVbmeta_SystemVbmeta) {
+TEST(FsAvbUtilTest, DISABLED_LoadAndVerifyVbmeta_SystemVbmeta) {
     Fstab fstab;
     EXPECT_TRUE(ReadDefaultFstab(&fstab));
 
@@ -51,7 +54,7 @@
     EXPECT_NE("", out_public_key_data);
 }
 
-TEST(PublicFsAvbDeviceTest, GetHashtreeDescriptor_SystemOther) {
+TEST(FsAvbUtilTest, GetHashtreeDescriptor_SystemOther) {
     // Non-A/B device doesn't have system_other partition.
     if (fs_mgr_get_slot_suffix() == "") return;
 
@@ -90,4 +93,55 @@
     EXPECT_NE(nullptr, hashtree_desc);
 }
 
+TEST(AvbHandleTest, LoadAndVerifyVbmeta_SystemOther) {
+    // Non-A/B device doesn't have system_other partition.
+    if (fs_mgr_get_slot_suffix() == "") return;
+
+    // Skip running this test if system_other is a logical partition.
+    // Note that system_other is still a physical partition on "retrofit" devices.
+    if (android::base::GetBoolProperty("ro.boot.dynamic_partitions", false) &&
+        !android::base::GetBoolProperty("ro.boot.dynamic_partitions_retrofit", false)) {
+        return;
+    }
+
+    Fstab fstab;
+    EXPECT_TRUE(ReadFstabFromFile("/system/etc/fstab.postinstall", &fstab));
+
+    // It should have two lines in the fstab, the first for logical system_other,
+    // the other for physical system_other.
+    EXPECT_EQ(2UL, fstab.size());
+
+    // Use the 2nd fstab entry, which is for physical system_other partition.
+    FstabEntry* system_other_entry = &fstab[1];
+    // Assign the default key if it's not specified in the fstab.
+    if (system_other_entry->avb_key.empty()) {
+        system_other_entry->avb_key = "/system/etc/security/avb/system_other.avbpubkey";
+    }
+    auto avb_handle = AvbHandle::LoadAndVerifyVbmeta(*system_other_entry);
+    EXPECT_NE(nullptr, avb_handle) << "Failed to load system_other vbmeta. Try 'adb root'?";
+    EXPECT_EQ(AvbHandleStatus::kSuccess, avb_handle->status());
+}
+
+TEST(AvbHandleTest, GetSecurityPatchLevel) {
+    Fstab fstab;
+    EXPECT_TRUE(ReadDefaultFstab(&fstab));
+
+    auto avb_handle = AvbHandle::LoadAndVerifyVbmeta();
+    EXPECT_NE(nullptr, avb_handle) << "Failed to load inline vbmeta. Try 'adb root'?";
+    EXPECT_EQ(AvbHandleStatus::kSuccess, avb_handle->status());
+
+    // Gets security patch level with format: YYYY-MM-DD (e.g., 2019-04-05).
+    FstabEntry* system_entry = GetEntryForMountPoint(&fstab, "/system");
+    EXPECT_NE(nullptr, system_entry);
+    EXPECT_EQ(10UL, avb_handle->GetSecurityPatchLevel(*system_entry).length());
+
+    FstabEntry* vendor_entry = GetEntryForMountPoint(&fstab, "/vendor");
+    EXPECT_NE(nullptr, vendor_entry);
+    EXPECT_EQ(10UL, avb_handle->GetSecurityPatchLevel(*vendor_entry).length());
+
+    FstabEntry* product_entry = GetEntryForMountPoint(&fstab, "/product");
+    EXPECT_NE(nullptr, product_entry);
+    EXPECT_EQ(10UL, avb_handle->GetSecurityPatchLevel(*product_entry).length());
+}
+
 }  // namespace fs_avb_device_test
diff --git a/init/first_stage_mount.cpp b/init/first_stage_mount.cpp
index 898e28e..6e55c11a 100644
--- a/init/first_stage_mount.cpp
+++ b/init/first_stage_mount.cpp
@@ -189,6 +189,29 @@
     return true;
 }
 
+static bool IsStandaloneImageRollback(const AvbHandle& builtin_vbmeta,
+                                      const AvbHandle& standalone_vbmeta,
+                                      const FstabEntry& fstab_entry) {
+    std::string old_spl = builtin_vbmeta.GetSecurityPatchLevel(fstab_entry);
+    std::string new_spl = standalone_vbmeta.GetSecurityPatchLevel(fstab_entry);
+
+    bool rollbacked = false;
+    if (old_spl.empty() || new_spl.empty() || new_spl < old_spl) {
+        rollbacked = true;
+    }
+
+    if (rollbacked) {
+        LOG(ERROR) << "Image rollback detected for " << fstab_entry.mount_point
+                   << ", SPL switches from '" << old_spl << "' to '" << new_spl << "'";
+        if (AvbHandle::IsDeviceUnlocked()) {
+            LOG(INFO) << "Allowing rollbacked standalone image when the device is unlocked";
+            return false;
+        }
+    }
+
+    return rollbacked;
+}
+
 // Class Definitions
 // -----------------
 FirstStageMount::FirstStageMount(Fstab fstab)
@@ -746,7 +769,15 @@
                        << fstab_entry->mount_point;
             return true;  // Returns true to mount the partition directly.
         } else {
-            hashtree_result = AvbHandle::SetUpStandaloneAvbHashtree(
+            auto avb_standalone_handle = AvbHandle::LoadAndVerifyVbmeta(*fstab_entry);
+            if (!avb_standalone_handle) {
+                LOG(ERROR) << "Failed to load offline vbmeta for " << fstab_entry->mount_point;
+                return false;
+            }
+            if (IsStandaloneImageRollback(*avb_handle_, *avb_standalone_handle, *fstab_entry)) {
+                return false;
+            }
+            hashtree_result = avb_standalone_handle->SetUpAvbHashtree(
                     fstab_entry, false /* wait_for_verity_dev */);
         }
     } else {