diff --git a/clang-tools-extra/clangd/JSONTransport.cpp b/clang-tools-extra/clangd/JSONTransport.cpp
--- a/clang-tools-extra/clangd/JSONTransport.cpp
+++ b/clang-tools-extra/clangd/JSONTransport.cpp
@@ -10,9 +10,11 @@
 #include "support/Cancellation.h"
 #include "support/Logger.h"
 #include "support/Shutdown.h"
+#include "support/ThreadSignalHandler.h"
 #include "llvm/ADT/SmallString.h"
 #include "llvm/Support/Errno.h"
 #include "llvm/Support/Error.h"
+#include "llvm/Support/Threading.h"
 #include <system_error>
 
 namespace clang {
@@ -109,6 +111,11 @@
         return llvm::errorCodeToError(
             std::error_code(errno, std::system_category()));
       if (readRawMessage(JSON)) {
+        ThreadSignalHandler ScopedHandler([JSON]() {
+          auto &OS = llvm::errs();
+          OS << "Signalled while processing message:\n";
+          OS << JSON << "\r\n";
+        });
         if (auto Doc = llvm::json::parse(JSON)) {
           vlog(Pretty ? "<<< {0:2}\n" : "<<< {0}\n", *Doc);
           if (!handleMessage(std::move(*Doc), Handler))
diff --git a/clang-tools-extra/clangd/TUScheduler.cpp b/clang-tools-extra/clangd/TUScheduler.cpp
--- a/clang-tools-extra/clangd/TUScheduler.cpp
+++ b/clang-tools-extra/clangd/TUScheduler.cpp
@@ -58,6 +58,7 @@
 #include "support/Logger.h"
 #include "support/MemoryTree.h"
 #include "support/Path.h"
+#include "support/ThreadSignalHandler.h"
 #include "support/Threading.h"
 #include "support/Trace.h"
 #include "clang/Frontend/CompilerInvocation.h"
@@ -591,6 +592,8 @@
   Deadline scheduleLocked();
   /// Should the first task in the queue be skipped instead of run?
   bool shouldSkipHeadLocked() const;
+  /// Called by thread local signal handler.
+  void printRequestContextOnSignal() const;
 
   struct Request {
     llvm::unique_function<void()> Action;
@@ -1281,6 +1284,8 @@
         Status.ASTActivity.Name = CurrentRequest->Name;
       });
       WithContext WithProvidedContext(ContextProvider(FileName));
+      ThreadSignalHandler ScopedHandler(
+          [this]() { printRequestContextOnSignal(); });
       CurrentRequest->Action();
     }
 
@@ -1371,6 +1376,22 @@
   llvm_unreachable("Unknown WantDiagnostics");
 }
 
+void ASTWorker::printRequestContextOnSignal() const {
+  auto &OS = llvm::errs();
+  OS << "Signalled during AST action:\n";
+  auto &Command = FileInputs.CompileCommand;
+  OS << "Filename: " << Command.Filename << "\n";
+  OS << "Directory: " << Command.Directory << "\n";
+  OS << "Command Line:";
+  for (auto &Arg : Command.CommandLine) {
+    OS << " " << Arg;
+  }
+  OS << "\n";
+  OS << "Version: " << FileInputs.Version << "\n";
+  OS << "Contents:\n";
+  OS << FileInputs.Contents << "\n";
+}
+
 bool ASTWorker::blockUntilIdle(Deadline Timeout) const {
   auto WaitUntilASTWorkerIsIdle = [&] {
     std::unique_lock<std::mutex> Lock(Mutex);
diff --git a/clang-tools-extra/clangd/support/CMakeLists.txt b/clang-tools-extra/clangd/support/CMakeLists.txt
--- a/clang-tools-extra/clangd/support/CMakeLists.txt
+++ b/clang-tools-extra/clangd/support/CMakeLists.txt
@@ -24,6 +24,7 @@
   MemoryTree.cpp
   Path.cpp
   Shutdown.cpp
+  ThreadSignalHandler.cpp
   Threading.cpp
   ThreadsafeFS.cpp
   Trace.cpp
diff --git a/clang-tools-extra/clangd/support/ThreadSignalHandler.h b/clang-tools-extra/clangd/support/ThreadSignalHandler.h
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/clangd/support/ThreadSignalHandler.h
@@ -0,0 +1,31 @@
+//===--- ThreadSignalHandler.h - Thread local signal handling ----*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include <functional>
+
+namespace clang {
+namespace clangd {
+
+using ThreadSignalHandlerCallback = std::function<void(void)>;
+
+class ThreadSignalHandler {
+public:
+  ThreadSignalHandler(const ThreadSignalHandlerCallback &ThreadLocalCallback);
+  ~ThreadSignalHandler();
+
+  ThreadSignalHandler(ThreadSignalHandler &&);
+  ThreadSignalHandler(const ThreadSignalHandler &) = delete;
+  ThreadSignalHandler &operator=(ThreadSignalHandler &&) = delete;
+  ThreadSignalHandler &operator=(const ThreadSignalHandler &) = delete;
+
+private:
+  ThreadSignalHandlerCallback Callback;
+};
+
+} // namespace clangd
+} // namespace clang
diff --git a/clang-tools-extra/clangd/support/ThreadSignalHandler.cpp b/clang-tools-extra/clangd/support/ThreadSignalHandler.cpp
new file mode 100644
--- /dev/null
+++ b/clang-tools-extra/clangd/support/ThreadSignalHandler.cpp
@@ -0,0 +1,50 @@
+//===--- ThreadSignalHandler.cpp - Thread local signal handling --*- C++-*-===//
+//
+// Part of the LLVM Project, under the Apache License v2.0 with LLVM Exceptions.
+// See https://llvm.org/LICENSE.txt for license information.
+// SPDX-License-Identifier: Apache-2.0 WITH LLVM-exception
+//
+//===----------------------------------------------------------------------===//
+
+#include "support/ThreadSignalHandler.h"
+#include "llvm/Support/Signals.h"
+#include "llvm/Support/ThreadLocal.h"
+
+using namespace clang::clangd;
+
+static llvm::sys::ThreadLocal<ThreadSignalHandlerCallback> CurrentCallback;
+
+static void registerSignalHandlerIfNeeded() {
+  static llvm::once_flag RegisterOnceFlag;
+  llvm::call_once(RegisterOnceFlag, []() {
+    auto PrintInputs = [](void *Cookie) {
+      ThreadSignalHandlerCallback *Callback = CurrentCallback.get();
+      // TODO: ignore non thread local signals like SIGTERM
+      if (Callback) {
+        (*Callback)();
+      }
+    };
+    llvm::sys::AddSignalHandler(PrintInputs, nullptr);
+  });
+}
+
+ThreadSignalHandler::ThreadSignalHandler(
+    const ThreadSignalHandlerCallback &ThreadLocalCallback)
+    : Callback(ThreadLocalCallback) {
+  assert(CurrentCallback.get() == nullptr);
+  registerSignalHandlerIfNeeded();
+  CurrentCallback.set(&Callback);
+}
+
+ThreadSignalHandler::ThreadSignalHandler(ThreadSignalHandler &&RHS)
+    : Callback(RHS.Callback) {
+  assert(CurrentCallback.get() == &RHS.Callback);
+  RHS.Callback = nullptr;
+  CurrentCallback.set(&Callback);
+}
+
+ThreadSignalHandler::~ThreadSignalHandler() {
+  if (Callback != nullptr) { // haven't been moved
+    CurrentCallback.set(nullptr);
+  }
+}