diff --git a/src/policy/packages.h b/src/policy/packages.h
--- a/src/policy/packages.h
+++ b/src/policy/packages.h
@@ -6,10 +6,17 @@
 #define BITCOIN_POLICY_PACKAGES_H
 
 #include <consensus/validation.h>
+#include <policy/policy.h>
 #include <primitives/transaction.h>
 
 #include <vector>
 
+/** Default maximum number of transactions in a package. */
+static constexpr uint32_t MAX_PACKAGE_COUNT{50};
+/** Default maximum total size of transactions in a package in KB. */
+static constexpr uint32_t MAX_PACKAGE_SIZE{101};
+static_assert(MAX_PACKAGE_SIZE * 1000 >= MAX_STANDARD_TX_SIZE);
+
 /**
  * A "reason" why a package was invalid. It may be that one or more of the
  * included transactions is invalid or the package itself violates our rules.
diff --git a/src/test/txvalidation_tests.cpp b/src/test/txvalidation_tests.cpp
--- a/src/test/txvalidation_tests.cpp
+++ b/src/test/txvalidation_tests.cpp
@@ -5,6 +5,8 @@
 #include <config.h>
 #include <consensus/validation.h>
 #include <key_io.h>
+#include <policy/packages.h>
+#include <policy/policy.h>
 #include <primitives/transaction.h>
 #include <script/script.h>
 #include <script/standard.h>
@@ -53,6 +55,25 @@
     BOOST_CHECK(result.m_state.GetResult() == TxValidationResult::TX_CONSENSUS);
 }
 
+// Create placeholder transactions that have no meaning.
+inline CTransactionRef create_placeholder_tx(size_t num_inputs,
+                                             size_t num_outputs) {
+    CMutableTransaction mtx = CMutableTransaction();
+    mtx.vin.resize(num_inputs);
+    mtx.vout.resize(num_outputs);
+    auto random_script = CScript() << ToByteVector(InsecureRand256())
+                                   << ToByteVector(InsecureRand256());
+    for (size_t i{0}; i < num_inputs; ++i) {
+        mtx.vin[i].prevout = COutPoint(TxId{InsecureRand256()}, 0);
+        mtx.vin[i].scriptSig = random_script;
+    }
+    for (size_t o{0}; o < num_outputs; ++o) {
+        mtx.vout[o].nValue = 1 * CENT;
+        mtx.vout[o].scriptPubKey = random_script;
+    }
+    return MakeTransactionRef(mtx);
+}
+
 BOOST_FIXTURE_TEST_CASE(package_tests, TestChain100Setup) {
     LOCK(cs_main);
     unsigned int initialPoolSize = m_node.mempool->size();
@@ -96,6 +117,58 @@
                         "Package validation unexpectedly failed: "
                             << it_child->second.m_state.GetRejectReason());
 
+    // Packages can't have more than 50 transactions.
+    Package package_too_many;
+    package_too_many.reserve(MAX_PACKAGE_COUNT + 1);
+    for (size_t i{0}; i < MAX_PACKAGE_COUNT + 1; ++i) {
+        package_too_many.emplace_back(create_placeholder_tx(1, 1));
+    }
+    auto result_too_many = ProcessNewPackage(
+        GetConfig(), m_node.chainman->ActiveChainstate(), *m_node.mempool,
+        package_too_many, /* test_accept */ true);
+    BOOST_CHECK(result_too_many.m_state.IsInvalid());
+    BOOST_CHECK_EQUAL(result_too_many.m_state.GetResult(),
+                      PackageValidationResult::PCKG_POLICY);
+    BOOST_CHECK_EQUAL(result_too_many.m_state.GetRejectReason(),
+                      "package-too-many-transactions");
+
+    // Packages can't have a total size of more than 101KvB.
+    CTransactionRef large_ptx = create_placeholder_tx(150, 150);
+    Package package_too_large;
+    auto size_large = GetVirtualTransactionSize(*large_ptx);
+    size_t total_size{0};
+    while (total_size <= MAX_PACKAGE_SIZE * 1000) {
+        package_too_large.push_back(large_ptx);
+        total_size += size_large;
+    }
+    BOOST_CHECK(package_too_large.size() <= MAX_PACKAGE_COUNT);
+    auto result_too_large = ProcessNewPackage(
+        GetConfig(), m_node.chainman->ActiveChainstate(), *m_node.mempool,
+        package_too_large, /* test_accept */ true);
+    BOOST_CHECK(result_too_large.m_state.IsInvalid());
+    BOOST_CHECK_EQUAL(result_too_large.m_state.GetResult(),
+                      PackageValidationResult::PCKG_POLICY);
+    BOOST_CHECK_EQUAL(result_too_large.m_state.GetRejectReason(),
+                      "package-too-large");
+
+    // A single, giant transaction submitted through ProcessNewPackage fails on
+    // single tx policy.
+    CTransactionRef giant_ptx = create_placeholder_tx(999, 999);
+    BOOST_CHECK(GetVirtualTransactionSize(*giant_ptx) >
+                MAX_PACKAGE_SIZE * 1000);
+    auto result_single_large =
+        ProcessNewPackage(GetConfig(), m_node.chainman->ActiveChainstate(),
+                          *m_node.mempool, {giant_ptx}, /* test_accept */ true);
+    BOOST_CHECK(result_single_large.m_state.IsInvalid());
+    BOOST_CHECK_EQUAL(result_single_large.m_state.GetResult(),
+                      PackageValidationResult::PCKG_TX);
+    BOOST_CHECK_EQUAL(result_single_large.m_state.GetRejectReason(),
+                      "transaction failed");
+    auto it_giant_tx =
+        result_single_large.m_tx_results.find(giant_ptx->GetId());
+    BOOST_CHECK(it_giant_tx != result_single_large.m_tx_results.end());
+    BOOST_CHECK_EQUAL(it_giant_tx->second.m_state.GetRejectReason(), "tx-size");
+
     // Check that mempool size hasn't changed.
     BOOST_CHECK_EQUAL(m_node.mempool->size(), initialPoolSize);
 }
diff --git a/src/validation.cpp b/src/validation.cpp
--- a/src/validation.cpp
+++ b/src/validation.cpp
@@ -737,6 +737,26 @@
     PackageValidationState package_state;
     const size_t package_count = txns.size();
 
+    // These context-free package limits can be checked before taking the
+    // mempool lock.
+    if (package_count > MAX_PACKAGE_COUNT) {
+        package_state.Invalid(PackageValidationResult::PCKG_POLICY,
+                              "package-too-many-transactions");
+        return PackageMempoolAcceptResult(package_state, {});
+    }
+
+    const int64_t total_size = std::accumulate(
+        txns.cbegin(), txns.cend(), 0, [](int64_t sum, const auto &tx) {
+            return sum + GetVirtualTransactionSize(*tx);
+        });
+    // If the package only contains 1 tx, it's better to report the policy
+    // violation on individual tx size.
+    if (package_count > 1 && total_size > MAX_PACKAGE_SIZE * 1000) {
+        package_state.Invalid(PackageValidationResult::PCKG_POLICY,
+                              "package-too-large");
+        return PackageMempoolAcceptResult(package_state, {});
+    }
+
     std::vector<Workspace> workspaces{};
     workspaces.reserve(package_count);
     std::transform(txns.cbegin(), txns.cend(), std::back_inserter(workspaces),