diff --git a/src/crypto/pem/pem_info.cc b/src/crypto/pem/pem_info.cc
index 27d4edc50..873c21ba1 100644
--- a/src/crypto/pem/pem_info.cc
+++ b/src/crypto/pem/pem_info.cc
@@ -168,7 +168,8 @@ STACK_OF(X509_INFO) *PEM_X509_INFO_read_bio(BIO *bp, STACK_OF(X509_INFO) *sk,
       key_type = EVP_PKEY_EC;
     }
 
-    // If a private key has a header, assume it is encrypted.
+    // If a private key has a header, assume it is encrypted. This function does
+    // not decrypt private keys.
     if (key_type != EVP_PKEY_NONE && strlen(header) > 10) {
       if (info->x_pkey != NULL) {
         if (!sk_X509_INFO_push(ret, info)) {
@@ -179,7 +180,7 @@ STACK_OF(X509_INFO) *PEM_X509_INFO_read_bio(BIO *bp, STACK_OF(X509_INFO) *sk,
           goto err;
         }
       }
-      // Historically, raw entries pushed an empty key.
+      // Use an empty key as a placeholder.
       info->x_pkey = X509_PKEY_new();
       if (info->x_pkey == NULL ||
           !PEM_get_EVP_CIPHER_INFO(header, &info->enc_cipher)) {
diff --git a/src/crypto/x509/x509_test.cc b/src/crypto/x509/x509_test.cc
index ad1297af4..27facf032 100644
--- a/src/crypto/x509/x509_test.cc
+++ b/src/crypto/x509/x509_test.cc
@@ -2974,6 +2974,8 @@ TEST(X509Test, MismatchAlgorithms) {
                           X509_R_SIGNATURE_ALGORITHM_MISMATCH));
 }
 
+// TODO(crbug.com/387737061): Test that this function can decrypt certificates
+// and CRLs, even though it leaves encrypted private keys alone.
 TEST(X509Test, PEMX509Info) {
   std::string cert = kRootCAPEM;
   auto cert_obj = CertFromPEM(kRootCAPEM);
@@ -2987,6 +2989,9 @@ TEST(X509Test, PEMX509Info) {
   auto crl_obj = CRLFromPEM(kBasicCRL);
   ASSERT_TRUE(crl_obj);
 
+  bssl::UniquePtr<EVP_PKEY> placeholder_key(EVP_PKEY_new());
+  ASSERT_TRUE(placeholder_key);
+
   std::string unknown =
       "-----BEGIN UNKNOWN-----\n"
       "AAAA\n"
@@ -2997,6 +3002,16 @@ TEST(X509Test, PEMX509Info) {
       "AAAA\n"
       "-----END CERTIFICATE-----\n";
 
+  std::string encrypted_key = R"(-----BEGIN EC PRIVATE KEY-----
+Proc-Type: 4,ENCRYPTED
+DEK-Info: AES-128-CBC,B3B2988AECAE6EAB0D043105994C1123
+
+RK7DUIGDHWTFh2rpTX+dR88hUyC1PyDlIULiNCkuWFwHrJbc1gM6hMVOKmU196XC
+iITrIKmilFm9CPD6Tpfk/NhI/QPxyJlk1geIkxpvUZ2FCeMuYI1To14oYOUKv14q
+wr6JtaX2G+pOmwcSPymZC4u2TncAP7KHgS8UGcMw8CE=
+-----END EC PRIVATE KEY-----
+)";
+
   // Each X509_INFO contains at most one certificate, CRL, etc. The format
   // creates a new X509_INFO when a repeated type is seen.
   std::string pem =
@@ -3012,7 +3027,12 @@ TEST(X509Test, PEMX509Info) {
       // Doubled keys also start new entries.
       rsa + rsa + rsa + rsa + crl +
       // As do CRLs.
-      crl + crl;
+      crl + crl +
+      // Encrypted private keys are not decrypted (decryption failures would be
+      // fatal) and just returned as placeholder.
+      crl + cert + encrypted_key +
+      // Placeholder keys are still keys, so a new key starts a new entry.
+      rsa;
 
   const struct ExpectedInfo {
     const X509 *cert;
@@ -3032,6 +3052,8 @@ TEST(X509Test, PEMX509Info) {
       {nullptr, rsa_obj.get(), crl_obj.get()},
       {nullptr, nullptr, crl_obj.get()},
       {nullptr, nullptr, crl_obj.get()},
+      {cert_obj.get(), placeholder_key.get(), crl_obj.get()},
+      {nullptr, rsa_obj.get(), nullptr},
   };
 
   auto check_info = [](const ExpectedInfo *expected, const X509_INFO *info) {
@@ -3047,8 +3069,14 @@ TEST(X509Test, PEMX509Info) {
     }
     if (expected->key != nullptr) {
       ASSERT_NE(nullptr, info->x_pkey);
-      // EVP_PKEY_cmp returns one if the keys are equal.
-      EXPECT_EQ(1, EVP_PKEY_cmp(expected->key, info->x_pkey->dec_pkey));
+      if (EVP_PKEY_id(expected->key) == EVP_PKEY_NONE) {
+        // Expect a placeholder key.
+        EXPECT_FALSE(info->x_pkey->dec_pkey);
+      } else {
+        // EVP_PKEY_cmp returns one if the keys are equal.
+        ASSERT_TRUE(info->x_pkey->dec_pkey);
+        EXPECT_EQ(1, EVP_PKEY_cmp(expected->key, info->x_pkey->dec_pkey));
+      }
     } else {
       EXPECT_EQ(nullptr, info->x_pkey);
     }
diff --git a/src/include/openssl/pem.h b/src/include/openssl/pem.h
index 28bf3f286..3711d8a0e 100644
--- a/src/include/openssl/pem.h
+++ b/src/include/openssl/pem.h
@@ -307,6 +307,14 @@ OPENSSL_EXPORT int PEM_ASN1_write_bio(i2d_of_void *i2d, const char *name,
 // on success. In this case, the caller retains ownership of |sk| in both
 // success and failure.
 //
+// This function will decrypt any encrypted certificates in |bp|, using |cb|,
+// but it will not decrypt encrypted private keys. Encrypted private keys are
+// instead represented as placeholder |X509_INFO| objects with an empty |x_pkey|
+// field. This allows this function to be used with inputs with unencrypted
+// certificates, but encrypted passwords, without knowing the password. However,
+// it also means that this function cannot be used to decrypt the private key
+// when the password is known.
+//
 // WARNING: If the input contains "TRUSTED CERTIFICATE" PEM blocks, this
 // function parses auxiliary properties as in |d2i_X509_AUX|. Passing untrusted
 // input to this function allows an attacker to influence those properties. See
diff --git a/src/rust/bssl-crypto/src/lib.rs b/src/rust/bssl-crypto/src/lib.rs
index d1abb93da..db03b5599 100644
--- a/src/rust/bssl-crypto/src/lib.rs
+++ b/src/rust/bssl-crypto/src/lib.rs
@@ -476,8 +476,7 @@ fn cbb_to_vec<F: FnOnce(*mut bssl_sys::CBB)>(len: usize, func: F) -> Vec<u8> {
             bssl_sys::CBB_init_fixed(cbb, boxed.as_mut_ptr() as *mut u8, len) == 1
         })
     }
-    // `CBB_init` only fails if out of memory, which isn't something that this
-    // crate handles.
+    // `CBB_init_fixed` never fails and does not allocate.
     .unwrap();
 
     func(&mut cbb);