diff --git a/fs_mgr/liblp/builder.cpp b/fs_mgr/liblp/builder.cpp
index 6dc288e..77c9c28 100644
--- a/fs_mgr/liblp/builder.cpp
+++ b/fs_mgr/liblp/builder.cpp
@@ -171,6 +171,13 @@
         }
     }
 
+    if (IPropertyFetcher::GetInstance()->GetBoolProperty("ro.virtual_ab.enabled", false)) {
+        if (!UpdateMetadataForInPlaceSnapshot(metadata.get(), source_slot_number,
+                                              target_slot_number)) {
+            return nullptr;
+        }
+    }
+
     return New(*metadata.get(), &opener);
 }
 
diff --git a/fs_mgr/liblp/utility.cpp b/fs_mgr/liblp/utility.cpp
index 338b525..17f05aa 100644
--- a/fs_mgr/liblp/utility.cpp
+++ b/fs_mgr/liblp/utility.cpp
@@ -24,6 +24,10 @@
 #include <sys/ioctl.h>
 #endif
 
+#include <map>
+#include <string>
+#include <vector>
+
 #include <android-base/file.h>
 #include <ext4_utils/ext4_utils.h>
 #include <openssl/sha.h>
@@ -182,6 +186,14 @@
     return true;
 }
 
+bool UpdatePartitionName(LpMetadataPartition* partition, const std::string& name) {
+    if (name.size() > sizeof(partition->name)) {
+        return false;
+    }
+    strncpy(partition->name, name.c_str(), sizeof(partition->name));
+    return true;
+}
+
 bool SetBlockReadonly(int fd, bool readonly) {
 #if defined(__linux__)
     int val = readonly;
@@ -207,5 +219,70 @@
     return base::unique_fd(open(path, flags));
 }
 
+bool UpdateMetadataForInPlaceSnapshot(LpMetadata* metadata, uint32_t source_slot_number,
+                                      uint32_t target_slot_number) {
+    std::string source_slot_suffix = SlotSuffixForSlotNumber(source_slot_number);
+    std::string target_slot_suffix = SlotSuffixForSlotNumber(target_slot_number);
+
+    // There can be leftover groups with target suffix on retrofit devices.
+    // They are useless now, so delete.
+    std::vector<LpMetadataPartitionGroup*> new_group_ptrs;
+    for (auto& group : metadata->groups) {
+        std::string group_name = GetPartitionGroupName(group);
+        std::string slot_suffix = GetPartitionSlotSuffix(group_name);
+        // Don't add groups with target slot suffix.
+        if (slot_suffix == target_slot_suffix) continue;
+        // Replace source slot suffix with target slot suffix.
+        if (slot_suffix == source_slot_suffix) {
+            std::string new_name = group_name.substr(0, group_name.size() - slot_suffix.size()) +
+                                   target_slot_suffix;
+            if (!UpdatePartitionGroupName(&group, new_name)) {
+                LERROR << "Group name too long: " << new_name;
+                return false;
+            }
+        }
+        new_group_ptrs.push_back(&group);
+    }
+
+    std::vector<LpMetadataPartition*> new_partition_ptrs;
+    for (auto& partition : metadata->partitions) {
+        std::string partition_name = GetPartitionName(partition);
+        std::string slot_suffix = GetPartitionSlotSuffix(partition_name);
+        // Don't add partitions with target slot suffix.
+        if (slot_suffix == target_slot_suffix) continue;
+        // Replace source slot suffix with target slot suffix.
+        if (slot_suffix == source_slot_suffix) {
+            std::string new_name =
+                    partition_name.substr(0, partition_name.size() - slot_suffix.size()) +
+                    target_slot_suffix;
+            if (!UpdatePartitionName(&partition, new_name)) {
+                LERROR << "Partition name too long: " << new_name;
+                return false;
+            }
+        }
+        // Update group index.
+        auto it = std::find(new_group_ptrs.begin(), new_group_ptrs.end(),
+                            &metadata->groups[partition.group_index]);
+        if (it == new_group_ptrs.end()) {
+            LWARN << "Removing partition " << partition_name << " from group "
+                  << GetPartitionGroupName(metadata->groups[partition.group_index])
+                  << "; this partition should not belong to this group!";
+            continue;  // not adding to new_partition_ptrs
+        }
+        partition.group_index = std::distance(new_group_ptrs.begin(), it);
+        new_partition_ptrs.push_back(&partition);
+    }
+
+    std::vector<LpMetadataPartition> new_partitions;
+    for (auto* p : new_partition_ptrs) new_partitions.emplace_back(std::move(*p));
+    metadata->partitions = std::move(new_partitions);
+
+    std::vector<LpMetadataPartitionGroup> new_groups;
+    for (auto* g : new_group_ptrs) new_groups.emplace_back(std::move(*g));
+    metadata->groups = std::move(new_groups);
+
+    return true;
+}
+
 }  // namespace fs_mgr
 }  // namespace android
diff --git a/fs_mgr/liblp/utility.h b/fs_mgr/liblp/utility.h
index 96f1717..25ab66b 100644
--- a/fs_mgr/liblp/utility.h
+++ b/fs_mgr/liblp/utility.h
@@ -89,12 +89,17 @@
 // Update names from C++ strings.
 bool UpdateBlockDevicePartitionName(LpMetadataBlockDevice* device, const std::string& name);
 bool UpdatePartitionGroupName(LpMetadataPartitionGroup* group, const std::string& name);
+bool UpdatePartitionName(LpMetadataPartition* partition, const std::string& name);
 
 // Call BLKROSET ioctl on fd so that fd is readonly / read-writable.
 bool SetBlockReadonly(int fd, bool readonly);
 
 ::android::base::unique_fd GetControlFileOrOpen(const char* path, int flags);
 
+// For Virtual A/B updates, modify |metadata| so that it can be written to |target_slot_number|.
+bool UpdateMetadataForInPlaceSnapshot(LpMetadata* metadata, uint32_t source_slot_number,
+                                      uint32_t target_slot_number);
+
 }  // namespace fs_mgr
 }  // namespace android
 
diff --git a/fs_mgr/liblp/utility_test.cpp b/fs_mgr/liblp/utility_test.cpp
index 15f7fff..cac3989 100644
--- a/fs_mgr/liblp/utility_test.cpp
+++ b/fs_mgr/liblp/utility_test.cpp
@@ -15,6 +15,7 @@
  */
 
 #include <gtest/gtest.h>
+#include <liblp/builder.h>
 #include <liblp/liblp.h>
 
 #include "utility.h"
@@ -75,3 +76,81 @@
     EXPECT_EQ(GetPartitionSlotSuffix("system_a"), "_a");
     EXPECT_EQ(GetPartitionSlotSuffix("system_b"), "_b");
 }
+
+namespace android {
+namespace fs_mgr {
+// Equality comparison for testing. In reality, equality of device_index doesn't
+// necessary mean equality of the block device.
+bool operator==(const LinearExtent& l, const LinearExtent& r) {
+    return l.device_index() == r.device_index() && l.physical_sector() == r.physical_sector() &&
+           l.end_sector() == r.end_sector();
+}
+}  // namespace fs_mgr
+}  // namespace android
+
+static std::vector<LinearExtent> GetPartitionExtents(Partition* p) {
+    std::vector<LinearExtent> extents;
+    for (auto&& extent : p->extents()) {
+        auto linear_extent = extent->AsLinearExtent();
+        if (!linear_extent) return {};
+        extents.push_back(*linear_extent);
+    }
+    return extents;
+}
+
+TEST(liblp, UpdateMetadataForInPlaceSnapshot) {
+    using std::unique_ptr;
+
+    unique_ptr<MetadataBuilder> builder = MetadataBuilder::New(1024 * 1024, 1024, 2);
+    ASSERT_NE(builder, nullptr);
+
+    ASSERT_TRUE(builder->AddGroup("group_a", 256 * 1024));
+    Partition* system_a = builder->AddPartition("system_a", "group_a", LP_PARTITION_ATTR_READONLY);
+    ASSERT_NE(system_a, nullptr);
+    ASSERT_TRUE(builder->ResizePartition(system_a, 40 * 1024));
+    Partition* vendor_a = builder->AddPartition("vendor_a", "group_a", LP_PARTITION_ATTR_READONLY);
+    ASSERT_NE(vendor_a, nullptr);
+    ASSERT_TRUE(builder->ResizePartition(vendor_a, 20 * 1024));
+
+    ASSERT_TRUE(builder->AddGroup("group_b", 258 * 1024));
+    Partition* system_b = builder->AddPartition("system_b", "group_b", LP_PARTITION_ATTR_READONLY);
+    ASSERT_NE(system_b, nullptr);
+    ASSERT_TRUE(builder->ResizePartition(system_b, 36 * 1024));
+    Partition* vendor_b = builder->AddPartition("vendor_b", "group_b", LP_PARTITION_ATTR_READONLY);
+    ASSERT_NE(vendor_b, nullptr);
+    ASSERT_TRUE(builder->ResizePartition(vendor_b, 32 * 1024));
+
+    auto system_a_extents = GetPartitionExtents(system_a);
+    ASSERT_FALSE(system_a_extents.empty());
+
+    auto vendor_a_extents = GetPartitionExtents(vendor_a);
+    ASSERT_FALSE(vendor_a_extents.empty());
+
+    auto metadata = builder->Export();
+    ASSERT_NE(nullptr, metadata);
+
+    ASSERT_TRUE(UpdateMetadataForInPlaceSnapshot(metadata.get(), 0, 1));
+
+    auto new_builder = MetadataBuilder::New(*metadata);
+    ASSERT_NE(nullptr, new_builder);
+
+    EXPECT_EQ(nullptr, new_builder->FindGroup("group_a"));
+    EXPECT_EQ(nullptr, new_builder->FindPartition("system_a"));
+    EXPECT_EQ(nullptr, new_builder->FindPartition("vendor_a"));
+
+    auto group_b = new_builder->FindGroup("group_b");
+    ASSERT_NE(nullptr, group_b);
+    ASSERT_EQ(256 * 1024, group_b->maximum_size());
+
+    auto new_system_b = new_builder->FindPartition("system_b");
+    ASSERT_NE(nullptr, new_system_b);
+    EXPECT_EQ(40 * 1024, new_system_b->size());
+    auto new_system_b_extents = GetPartitionExtents(new_system_b);
+    EXPECT_EQ(system_a_extents, new_system_b_extents);
+
+    auto new_vendor_b = new_builder->FindPartition("vendor_b");
+    ASSERT_NE(nullptr, new_vendor_b);
+    EXPECT_EQ(20 * 1024, new_vendor_b->size());
+    auto new_vendor_b_extents = GetPartitionExtents(new_vendor_b);
+    EXPECT_EQ(vendor_a_extents, new_vendor_b_extents);
+}