diff --git a/KeyUtil.cpp b/KeyUtil.cpp
index 12cae9b..c1a82fb 100644
--- a/KeyUtil.cpp
+++ b/KeyUtil.cpp
@@ -16,12 +16,14 @@
 
 #include "KeyUtil.h"
 
-#include <linux/fs.h>
 #include <iomanip>
 #include <sstream>
 #include <string>
 
+#include <fcntl.h>
+#include <linux/fs.h>
 #include <openssl/sha.h>
+#include <sys/ioctl.h>
 
 #include <android-base/file.h>
 #include <android-base/logging.h>
@@ -29,6 +31,7 @@
 
 #include "KeyStorage.h"
 #include "Utils.h"
+#include "fscrypt_uapi.h"
 
 namespace android {
 namespace vold {
@@ -45,6 +48,42 @@
     return true;
 }
 
+// Return true if the kernel supports the ioctls to add/remove fscrypt keys
+// directly to/from the filesystem.
+bool isFsKeyringSupported(void) {
+    static bool initialized = false;
+    static bool supported;
+
+    if (!initialized) {
+        android::base::unique_fd fd(open("/data", O_RDONLY | O_DIRECTORY | O_CLOEXEC));
+
+        // FS_IOC_ADD_ENCRYPTION_KEY with a NULL argument will fail with ENOTTY
+        // if the ioctl isn't supported.  Otherwise it will fail with another
+        // error code such as EFAULT.
+        errno = 0;
+        (void)ioctl(fd, FS_IOC_ADD_ENCRYPTION_KEY, NULL);
+        if (errno == ENOTTY) {
+            LOG(INFO) << "Kernel doesn't support FS_IOC_ADD_ENCRYPTION_KEY.  Falling back to "
+                         "session keyring";
+            supported = false;
+        } else {
+            if (errno != EFAULT) {
+                PLOG(WARNING) << "Unexpected error from FS_IOC_ADD_ENCRYPTION_KEY";
+            }
+            LOG(DEBUG) << "Detected support for FS_IOC_ADD_ENCRYPTION_KEY";
+            supported = true;
+        }
+        // There's no need to check for FS_IOC_REMOVE_ENCRYPTION_KEY, since it's
+        // guaranteed to be available if FS_IOC_ADD_ENCRYPTION_KEY is.  There's
+        // also no need to check for support on external volumes separately from
+        // /data, since either the kernel supports the ioctls on all
+        // fscrypt-capable filesystems or it doesn't.
+
+        initialized = true;
+    }
+    return supported;
+}
+
 // Get raw keyref - used to make keyname and to pass to ioctl
 static std::string generateKeyRef(const uint8_t* key, int length) {
     SHA512_CTX c;
@@ -78,16 +117,20 @@
 
 static char const* const NAME_PREFIXES[] = {"ext4", "f2fs", "fscrypt", nullptr};
 
-static std::string keyname(const std::string& prefix, const std::string& raw_ref) {
+static std::string keyrefstring(const std::string& raw_ref) {
     std::ostringstream o;
-    o << prefix << ":";
     for (unsigned char i : raw_ref) {
         o << std::hex << std::setw(2) << std::setfill('0') << (int)i;
     }
     return o.str();
 }
 
-// Get the keyring we store all keys in
+static std::string buildLegacyKeyName(const std::string& prefix, const std::string& raw_ref) {
+    return prefix + ":" + keyrefstring(raw_ref);
+}
+
+// Get the ID of the keyring we store all fscrypt keys in when the kernel is too
+// old to support FS_IOC_ADD_ENCRYPTION_KEY and FS_IOC_REMOVE_ENCRYPTION_KEY.
 static bool fscryptKeyring(key_serial_t* device_keyring) {
     *device_keyring = keyctl_search(KEY_SPEC_SESSION_KEYRING, "keyring", "fscrypt", 0);
     if (*device_keyring == -1) {
@@ -97,19 +140,17 @@
     return true;
 }
 
-// Install password into global keyring
-// Return raw key reference for use in policy
-bool installKey(const KeyBuffer& key, std::string* raw_ref) {
+// Add an encryption key to the legacy global session keyring.
+static bool installKeyLegacy(const KeyBuffer& key, const std::string& raw_ref) {
     // Place fscrypt_key into automatically zeroing buffer.
     KeyBuffer fsKeyBuffer(sizeof(fscrypt_key));
     fscrypt_key& fs_key = *reinterpret_cast<fscrypt_key*>(fsKeyBuffer.data());
 
     if (!fillKey(key, &fs_key)) return false;
-    *raw_ref = generateKeyRef(fs_key.raw, fs_key.size);
     key_serial_t device_keyring;
     if (!fscryptKeyring(&device_keyring)) return false;
     for (char const* const* name_prefix = NAME_PREFIXES; *name_prefix != nullptr; name_prefix++) {
-        auto ref = keyname(*name_prefix, *raw_ref);
+        auto ref = buildLegacyKeyName(*name_prefix, raw_ref);
         key_serial_t key_id =
             add_key("logon", ref.c_str(), (void*)&fs_key, sizeof(fs_key), device_keyring);
         if (key_id == -1) {
@@ -122,12 +163,55 @@
     return true;
 }
 
-bool evictKey(const std::string& raw_ref) {
+// Install a file-based encryption key to the kernel, for use by encrypted files
+// on the specified filesystem.
+//
+// We use FS_IOC_ADD_ENCRYPTION_KEY if the kernel supports it.  Otherwise we add
+// the key to the legacy global session keyring.
+//
+// Returns %true on success, %false on failure.  On success also sets *raw_ref
+// to the raw key reference for use in the encryption policy.
+bool installKey(const KeyBuffer& key, const std::string& mountpoint, std::string* raw_ref) {
+    *raw_ref = generateKeyRef((const uint8_t*)key.data(), key.size());
+    if (!isFsKeyringSupported()) {
+        return installKeyLegacy(key, *raw_ref);
+    }
+
+    // Put the fscrypt_add_key_arg in an automatically-zeroing buffer, since we
+    // have to copy the raw key into it.
+    KeyBuffer arg_buf(sizeof(struct fscrypt_add_key_arg) + key.size(), 0);
+    struct fscrypt_add_key_arg* arg = (struct fscrypt_add_key_arg*)arg_buf.data();
+
+    arg->key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
+    memcpy(arg->key_spec.u.descriptor, raw_ref.c_str(), FSCRYPT_KEY_DESCRIPTOR_SIZE);
+
+    arg->raw_size = key.size();
+    memcpy(arg->raw, key.data(), key.size());
+
+    android::base::unique_fd fd(open(mountpoint.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC));
+    if (fd == -1) {
+        PLOG(ERROR) << "Failed to open " << mountpoint << " to install key";
+        return false;
+    }
+
+    if (ioctl(fd, FS_IOC_ADD_ENCRYPTION_KEY, arg) != 0) {
+        PLOG(ERROR) << "Failed to install fscrypt key with ref " << keyrefstring(*raw_ref) << " to "
+                    << mountpoint;
+        return false;
+    }
+
+    LOG(DEBUG) << "Installed fscrypt key with ref " << keyrefstring(*raw_ref) << " to "
+               << mountpoint;
+    return true;
+}
+
+// Remove an encryption key from the legacy global session keyring.
+static bool evictKeyLegacy(const std::string& raw_ref) {
     key_serial_t device_keyring;
     if (!fscryptKeyring(&device_keyring)) return false;
     bool success = true;
     for (char const* const* name_prefix = NAME_PREFIXES; *name_prefix != nullptr; name_prefix++) {
-        auto ref = keyname(*name_prefix, raw_ref);
+        auto ref = buildLegacyKeyName(*name_prefix, raw_ref);
         auto key_serial = keyctl_search(device_keyring, "logon", ref.c_str(), 0);
 
         // Unlink the key from the keyring.  Prefer unlinking to revoking or
@@ -144,9 +228,50 @@
     return success;
 }
 
+// Evict a file-based encryption key from the kernel.
+//
+// We use FS_IOC_REMOVE_ENCRYPTION_KEY if the kernel supports it.  Otherwise we
+// remove the key from the legacy global session keyring.
+//
+// In the latter case, the caller is responsible for dropping caches.
+bool evictKey(const std::string& mountpoint, const std::string& raw_ref) {
+    if (!isFsKeyringSupported()) {
+        return evictKeyLegacy(raw_ref);
+    }
+
+    android::base::unique_fd fd(open(mountpoint.c_str(), O_RDONLY | O_DIRECTORY | O_CLOEXEC));
+    if (fd == -1) {
+        PLOG(ERROR) << "Failed to open " << mountpoint << " to evict key";
+        return false;
+    }
+
+    struct fscrypt_remove_key_arg arg;
+    memset(&arg, 0, sizeof(arg));
+
+    arg.key_spec.type = FSCRYPT_KEY_SPEC_TYPE_DESCRIPTOR;
+    memcpy(arg.key_spec.u.descriptor, raw_ref.c_str(), FSCRYPT_KEY_DESCRIPTOR_SIZE);
+
+    std::string ref = keyrefstring(raw_ref);
+
+    if (ioctl(fd, FS_IOC_REMOVE_ENCRYPTION_KEY, &arg) != 0) {
+        PLOG(ERROR) << "Failed to evict fscrypt key with ref " << ref << " from " << mountpoint;
+        return false;
+    }
+
+    LOG(DEBUG) << "Evicted fscrypt key with ref " << ref << " from " << mountpoint;
+    if (arg.removal_status_flags & FSCRYPT_KEY_REMOVAL_STATUS_FLAG_OTHER_USERS) {
+        // Should never happen because keys are only added/removed as root.
+        LOG(ERROR) << "Unexpected case: key with ref " << ref << " is still added by other users!";
+    } else if (arg.removal_status_flags & FSCRYPT_KEY_REMOVAL_STATUS_FLAG_FILES_BUSY) {
+        LOG(ERROR) << "Files still open after removing key with ref " << ref
+                   << ".  These files were not locked!";
+    }
+    return true;
+}
+
 bool retrieveAndInstallKey(bool create_if_absent, const KeyAuthentication& key_authentication,
                            const std::string& key_path, const std::string& tmp_path,
-                           std::string* key_ref) {
+                           const std::string& volume_uuid, std::string* key_ref) {
     KeyBuffer key;
     if (pathExists(key_path)) {
         LOG(DEBUG) << "Key exists, using: " << key_path;
@@ -161,7 +286,7 @@
         if (!storeKeyAtomically(key_path, tmp_path, key_authentication, key)) return false;
     }
 
-    if (!installKey(key, key_ref)) {
+    if (!installKey(key, BuildDataPath(volume_uuid), key_ref)) {
         LOG(ERROR) << "Failed to install key in " << key_path;
         return false;
     }