diff --git a/patches/abseil_windows_gnullvm_thread_identity.patch b/patches/abseil_windows_gnullvm_thread_identity.patch
new file mode 100644
index 0000000000..27c4ecf71f
--- /dev/null
+++ b/patches/abseil_windows_gnullvm_thread_identity.patch
@@ -0,0 +1,16 @@
+# What: avoid MinGW pthread TLS linkage in Abseil thread identity selection.
+# Scope: one MinGW-specific preprocessor branch in Abseil's internal
+# thread-identity mode selection; no other Abseil behavior changes.
+
+diff --git a/absl/base/internal/thread_identity.h b/absl/base/internal/thread_identity.h
+--- a/absl/base/internal/thread_identity.h
++++ b/absl/base/internal/thread_identity.h
+@@ -217,6 +217,8 @@
+ #error ABSL_THREAD_IDENTITY_MODE cannot be directly set
+ #elif defined(ABSL_FORCE_THREAD_IDENTITY_MODE)
+ #define ABSL_THREAD_IDENTITY_MODE ABSL_FORCE_THREAD_IDENTITY_MODE
++#elif defined(__MINGW32__)
++#define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_CPP11
+ #elif defined(_WIN32) && !defined(__MINGW32__)
+ #define ABSL_THREAD_IDENTITY_MODE ABSL_THREAD_IDENTITY_MODE_USE_CPP11
+ #elif defined(__APPLE__) && defined(ABSL_HAVE_THREAD_LOCAL)
diff --git a/patches/llvm_windows_symlink_extract.patch b/patches/llvm_windows_symlink_extract.patch
new file mode 100644
index 0000000000..9f548636b2
--- /dev/null
+++ b/patches/llvm_windows_symlink_extract.patch
@@ -0,0 +1,64 @@
+diff --git a/extensions/llvm_source.bzl b/extensions/llvm_source.bzl
+index 89dcf81..cf27c92 100644
+--- a/extensions/llvm_source.bzl
++++ b/extensions/llvm_source.bzl
+@@ -83,6 +83,13 @@ def _llvm_source_archive_excludes():
+         "offload",
+         "libc/docs",
+         "libc/utils/gn",
++        # These entries are unix symlinks in the upstream source tarball.
++        # Windows tar.exe cannot materialize them during repository extraction,
++        # but nothing in our Bazel usage needs the symlink entrypoints.
++        "llvm/utils/mlgo-utils/extract_ir.py",
++        "llvm/utils/mlgo-utils/make_corpus.py",
++        "llvm/utils/mlgo-utils/combine_training_corpus.py",
++        "llvm/docs/_themes/llvm-theme",
+     ]
+ 
+     test_docs_subprojects = [
+diff --git a/runtimes/mingw/BUILD.bazel b/runtimes/mingw/BUILD.bazel
+index ebd99db..9eb5d5b 100644
+--- a/runtimes/mingw/BUILD.bazel
++++ b/runtimes/mingw/BUILD.bazel
+@@ -334,6 +334,30 @@ stub_library(
+     name = "stdc++",
+ )
+ 
++# Clang may inject -lssp and -lssp_nonshared for windows-gnu links.
++# Provide compatibility archives in the MinGW runtime search directory.
++stub_library(
++    name = "ssp",
++)
++
++stub_library(
++    name = "ssp_nonshared",
++)
++
++# Prebuilt MSVC archives can carry /DEFAULTLIB:libcmt.lib and
++# /DEFAULTLIB:oldnames.lib directives. Provide MinGW-compatible stand-ins so
++# lld can satisfy the lookup under windows-gnullvm.
++stub_library(
++    name = "libcmt",
++)
++
++copy_file(
++    name = "oldnames",
++    src = ":moldname",
++    out = "liboldnames.a",
++    visibility = ["//visibility:public"],
++)
++
+ copy_to_directory(
+     name = "mingw_crt_library_search_directory",
+     srcs = [
+@@ -344,6 +364,10 @@ copy_to_directory(
+         ":moldname",
++        ":oldnames",
+         ":pthread",
+         ":stdc++",
++        ":ssp",
++        ":ssp_nonshared",
++        ":libcmt",
+         ":ucrt",
+         ":ucrtbase",
+         ":ucrtbased",