diff --git a/common.gypi b/common.gypi
index 71712d308472..7eaad1e5ea1e 100644
--- a/common.gypi
+++ b/common.gypi
@@ -43,7 +43,7 @@
 
     # Reset this number to 0 on major V8 upgrades.
     # Increment by one for each non-official patch applied to deps/v8.
-    'v8_embedder_string': '-node.34',
+    'v8_embedder_string': '-node.35',
 
     ##### V8 defaults for Node.js #####
 
diff --git a/configure.py b/configure.py
index 8b3332a461f4..4bf8e2e39ee0 100755
--- a/configure.py
+++ b/configure.py
@@ -2261,9 +2261,6 @@ def configure_v8(o, configs):
       case 'none':
         warn('Temporal support disabled when compiling without ICU')
         options.v8_disable_temporal_support = True
-      case 'system-icu':
-        warn('Temporal support disabled when compiling with a shared ICU library')
-        options.v8_disable_temporal_support = True
   o['variables']['v8_enable_temporal_support'] = 0 if options.v8_disable_temporal_support else 1
   o['variables']['v8_trace_maps'] = 1 if options.trace_maps else 0
   o['variables']['v8_use_perfetto'] = 1 if options.with_perfetto else 0
@@ -2544,6 +2541,8 @@ def icu_download(path):
   # always set icu_small, node.gyp depends on it being defined.
   o['variables']['icu_small'] = b(False)
   o['variables']['icu_system'] = b(False)
+  # always set this
+  o['variables']['v8_enable_temporal_systemicu'] = 1
 
   # prevent data override
   o['defines'] += ['ICU_NO_USER_DATA_OVERRIDE']
diff --git a/deps/v8/BUILD.gn b/deps/v8/BUILD.gn
index 276641b09aa3..560d4d42a94f 100644
--- a/deps/v8/BUILD.gn
+++ b/deps/v8/BUILD.gn
@@ -1307,6 +1307,9 @@ config("features") {
   if (v8_enable_temporal_support) {
     defines += [ "V8_TEMPORAL_SUPPORT" ]
   }
+  if (v8_enable_temporal_systemicu) {
+    defines += [ "V8_ENABLE_TEMPORAL_SYSTEMICU" ]
+  }
   if (v8_enable_local_handle_zapping) {
     defines += [ "ENABLE_LOCAL_HANDLE_ZAPPING" ]
   }
@@ -3110,6 +3113,7 @@ generated_file("v8_generate_features_json") {
     v8_enable_hugepage = v8_enable_hugepage
     v8_enable_i18n_support = v8_enable_i18n_support
     v8_enable_temporal_support = v8_enable_temporal_support
+    v8_enable_temporal_systemicu = v8_enable_temporal_systemicu
     v8_enable_javascript_promise_hooks = v8_enable_javascript_promise_hooks
     v8_enable_lite_mode = v8_enable_lite_mode
     v8_enable_map_packing = v8_enable_map_packing
diff --git a/deps/v8/gni/v8.gni b/deps/v8/gni/v8.gni
index e29a7c5de3c4..ea430b3a0a93 100644
--- a/deps/v8/gni/v8.gni
+++ b/deps/v8/gni/v8.gni
@@ -63,6 +63,10 @@ declare_args() {
   # Furthermore, some architectures don't have Rust toolchains in Chromium
   v8_enable_temporal_support = !(defined(build_with_node) && build_with_node)
 
+  # by default, don't enable compiling Temporal with a system ICU4C
+  # (assume private headers are available)
+  v8_enable_temporal_systemicu = false
+
   # Use static libraries instead of source_sets.
   v8_static_library = false
 
diff --git a/deps/v8/src/objects/js-temporal-zoneinfo64.cc b/deps/v8/src/objects/js-temporal-zoneinfo64.cc
index 99dd3a84c1e5..007d63589c50 100644
--- a/deps/v8/src/objects/js-temporal-zoneinfo64.cc
+++ b/deps/v8/src/objects/js-temporal-zoneinfo64.cc
@@ -11,8 +11,36 @@
 #include "temporal_rs/TimeZone.hpp"
 
 #ifdef V8_INTL_SUPPORT
+#ifndef V8_ENABLE_TEMPORAL_SYSTEMICU
+// ICU internal header file
 #include "udatamem.h"
 #else
+/**
+ * Shadow definition of UDataMemory
+ * This is functionally identical to the definition in udatamem.h
+ * Irrelevant fields are marked 'ignored' and should not be used.
+ *
+ * This definition is copied here so that the result of udata_open()
+ * can be used and length-checked without needing to resort to
+ * calling internal ICU functions.
+ *
+ * Note, there is an ICU ticket,
+ * https://unicode-org.atlassian.net/browse/ICU-23400
+ * to consider whether the API surface should be changed
+ * here. If and when this is done, such an API could be used.
+ */
+struct UDataMemoryShadow {
+  const void* ignored1;
+  const void* data;  //< pointer to header of data object
+  const void* ignored2;
+  UBool ignored3;
+  void* ignored4;
+  void* ignored5;
+  int32_t
+      length;  //< length of entire region pointed to by data if known, else -1
+};
+#endif
+#else
 // Defined in builtins-temporal-zoneinfo64-data.cc, generated by
 // include-file-as-bytes.py
 extern "C" uint32_t zoneinfo64_static_data[];
@@ -30,17 +58,29 @@ ZoneInfo64Provider::ZoneInfo64Provider() {
     provider = temporal_rs::Provider::empty();
     return;
   }
+#ifndef V8_ENABLE_TEMPORAL_SYSTEMICU
   // NOT udata_getLength: this ignores the header,
   // and we're parsing resb files with the header
   auto length = memory->length;
   const void* data = udata_getRawMemory(memory);
-  DCHECK_WITH_MSG(length % 4 == 0, "ICU4C should align udata to uint32_t");
-  if (length % 4 != 0) {
-    // This really shouldn't happen: ICU4C aligns these files
-    // to 4 when baking them in
+#else
+  // reinterpret with a local struct
+  const UDataMemoryShadow* shadowMemory =
+      reinterpret_cast<const UDataMemoryShadow*>(memory);
+  // just need the length and data
+  auto length = shadowMemory->length;
+  auto data = shadowMemory->data;
+#endif
+  // This really shouldn't happen: ICU4C pads these files
+  // to 4 when baking them in
+  DCHECK_WITH_MSG(length % 4 == 0, "ICU4C should pad udata to uint32_t");
+  // Length may not be known. If we're not OK with that, don't proceed.
+  DCHECK_WITH_MSG(length != -1, "ICU4C usually knows the length");
+  if (length % 4 != 0 || length == -1) {
     provider = temporal_rs::Provider::empty();
     return;
   }
+  DCHECK_WITH_MSG(data != nullptr, "ICU4C returned nullptr");
 
   const uint32_t* data_32 = static_cast<const uint32_t*>(data);
   std::span<const uint32_t> data_span(data_32, length / 4);
diff --git a/tools/v8_gypfiles/features.gypi b/tools/v8_gypfiles/features.gypi
index 3f51d3da0044..95717992bcab 100644
--- a/tools/v8_gypfiles/features.gypi
+++ b/tools/v8_gypfiles/features.gypi
@@ -303,6 +303,11 @@
     # Enable Temporal API. Enabling this feature will
     # add a dependency on the temporal_rs library.
     'v8_enable_temporal_support%': 0,
+    # Enable Temporal even with system-icu.
+    # This will use an improved codepath which does not
+    # depend on internal ICU headers.
+    # This option can be on unconditionally.
+    'v8_enable_temporal_systemicu%': 1,
 
     # Lite mode disables a number of performance optimizations to reduce memory
     # at the cost of performance.
@@ -425,6 +430,9 @@
       }],
       ['v8_enable_temporal_support==1', {
         'defines': ['V8_TEMPORAL_SUPPORT',],
+      }],
+       ['v8_enable_temporal_systemicu==1', {
+        'defines': ['V8_ENABLE_TEMPORAL_SYSTEMICU',],
       }],
       # Refs: https://github.com/nodejs/node/pull/23801
       # ['v8_enable_handle_zapping==1', {