Index: lldb/include/lldb/Utility/StringExtractor.h
===================================================================
--- lldb/include/lldb/Utility/StringExtractor.h
+++ lldb/include/lldb/Utility/StringExtractor.h
@@ -10,8 +10,11 @@
 #define LLDB_UTILITY_STRINGEXTRACTOR_H
 
 #include "llvm/ADT/ArrayRef.h"
+#include "llvm/ADT/Optional.h"
 #include "llvm/ADT/StringRef.h"
 
+#include "lldb/lldb-types.h"
+
 #include <stddef.h>
 #include <stdint.h>
 #include <string>
@@ -95,6 +98,13 @@
 
   size_t GetHexByteStringTerminatedBy(std::string &str, char terminator);
 
+  // Read thread-id in the <tid> | "p" <pid> ["." <tid>] format, where <pid>
+  // and <tid> can be either "-1", "0" or a hex-encoded number.  Note that
+  // the function does not check for incorrect values such as -1.<tid != -1>.
+  // A pair of (llvm::None, llvm::None) is returned for malformed input.
+  std::pair<llvm::Optional<lldb::pid_t>, llvm::Optional<lldb::tid_t>>
+  GetPidTid();
+
   bool ConsumeFront(const llvm::StringRef &str);
 
   const char *Peek() {
Index: lldb/source/Utility/StringExtractor.cpp
===================================================================
--- lldb/source/Utility/StringExtractor.cpp
+++ lldb/source/Utility/StringExtractor.cpp
@@ -7,6 +7,7 @@
 //===----------------------------------------------------------------------===//
 
 #include "lldb/Utility/StringExtractor.h"
+#include "lldb/lldb-defines.h"
 #include "llvm/ADT/StringExtras.h"
 
 #include <tuple>
@@ -369,3 +370,56 @@
   while (m_index < n && llvm::isSpace(m_packet[m_index]))
     ++m_index;
 }
+
+std::pair<llvm::Optional<lldb::pid_t>, llvm::Optional<lldb::tid_t>>
+StringExtractor::GetPidTid() {
+  llvm::Optional<lldb::pid_t> pid = llvm::None;
+  llvm::Optional<lldb::tid_t> tid = llvm::None;
+
+  SkipSpaces();
+  if (m_index < m_packet.size() && m_packet[m_index] == 'p') {
+    // process identifier
+    ++m_index;
+    SkipSpaces();
+    if (m_index + 1 < m_packet.size() && m_packet[m_index] == '-' &&
+        m_packet[m_index + 1] == '1') {
+      // -1 is a special case
+      m_index += 2;
+      pid = LLDB_INVALID_PROCESS_ID;
+    } else {
+      uint64_t prev_index = m_index;
+      pid = GetHexMaxU64(false, 0);
+      if (m_index == prev_index || m_index == UINT64_MAX) {
+        // if index was not incremented or we overflowed, it failed
+        pid = llvm::None;
+        return {pid, tid};
+      }
+    }
+
+    // "." must follow if we expect TID too
+    SkipSpaces();
+    if (!(m_index < m_packet.size() && m_packet[m_index] == '.'))
+      return {pid, tid};
+    ++m_index;
+    SkipSpaces();
+  }
+
+  // thread identifier
+  if (m_index + 1 < m_packet.size() && m_packet[m_index] == '-' &&
+      m_packet[m_index + 1] == '1') {
+    // -1 is a special case
+    m_index += 2;
+    tid = LLDB_INVALID_PROCESS_ID;
+  } else {
+    uint64_t prev_index = m_index;
+    tid = GetHexMaxU64(false, 0);
+    if (m_index == prev_index || m_index == UINT64_MAX) {
+      // if index was not incremented or we overflowed, it failed
+      // (also reset pid since the value is incorrect)
+      pid = llvm::None;
+      tid = llvm::None;
+    }
+  }
+
+  return {pid, tid};
+}
Index: lldb/unittests/Utility/StringExtractorTest.cpp
===================================================================
--- lldb/unittests/Utility/StringExtractorTest.cpp
+++ lldb/unittests/Utility/StringExtractorTest.cpp
@@ -1,7 +1,9 @@
 #include "gtest/gtest.h"
+#include "gmock/gmock.h"
 #include <limits.h>
 
 #include "lldb/Utility/StringExtractor.h"
+#include "lldb/lldb-defines.h"
 
 namespace {
 class StringExtractorTest : public ::testing::Test {};
@@ -695,3 +697,193 @@
   ex.Reset("123456789ABCDEF000");
   EXPECT_EQ(0ull, ex.GetHexMaxU64(false, 0));
 }
+
+TEST_F(StringExtractorTest, GetPidTid) {
+  StringExtractor ex("");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  // invalid/short values
+
+  ex.Reset("narf");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset(";1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset(".1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("pnarf");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p;1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p.1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p1234.");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p1234.;1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("-2");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p1234.-2");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p-2");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p-2.1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  // overflow
+
+  ex.Reset("p10000000000000000");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p10000000000000000.0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("10000000000000000");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p0.10000000000000000");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  ex.Reset("p10000000000000000.10000000000000000");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, llvm::None));
+
+  // pure thread id
+
+  ex.Reset("0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, 0));
+
+  ex.Reset("-1");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, LLDB_INVALID_THREAD_ID));
+
+  ex.Reset("1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, 0x1234ULL));
+
+  ex.Reset("123456789ABCDEF0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(llvm::None, 0x123456789ABCDEF0ULL));
+
+  // pure process id
+
+  ex.Reset("p0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0, llvm::None));
+
+  ex.Reset("p-1");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(LLDB_INVALID_PROCESS_ID, llvm::None));
+
+  ex.Reset("p1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x1234ULL, llvm::None));
+
+  ex.Reset("p123456789ABCDEF0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x123456789ABCDEF0ULL, llvm::None));
+
+  // combined thread id + process id
+
+  ex.Reset("p0.0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0, 0));
+
+  ex.Reset("p0.-1");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0, LLDB_INVALID_THREAD_ID));
+
+  // NB: technically, specific thread with unspecified process is invalid
+  // but we do not filter that in StringExtractor
+
+  ex.Reset("p0.1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0, 0x1234ULL));
+
+  ex.Reset("p0.123456789ABCDEF0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0, 0x123456789ABCDEF0ULL));
+
+  ex.Reset("p-1.0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(LLDB_INVALID_PROCESS_ID, 0));
+
+  ex.Reset("p-1.-1");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(LLDB_INVALID_PROCESS_ID, LLDB_INVALID_THREAD_ID));
+
+  ex.Reset("p-1.1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(LLDB_INVALID_PROCESS_ID, 0x1234ULL));
+
+  ex.Reset("p-1.123456789ABCDEF0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(LLDB_INVALID_PROCESS_ID, 0x123456789ABCDEF0ULL));
+
+  ex.Reset("p1234.0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x1234ULL, 0));
+
+  ex.Reset("p1234.-1");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x1234ULL, LLDB_INVALID_THREAD_ID));
+
+  ex.Reset("p1234.123456789ABCDEF0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x1234ULL, 0x123456789ABCDEF0ULL));
+
+  ex.Reset("p123456789ABCDEF0.0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x123456789ABCDEF0ULL, 0));
+
+  ex.Reset("p123456789ABCDEF0.-1");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x123456789ABCDEF0ULL, LLDB_INVALID_THREAD_ID));
+
+  ex.Reset("p123456789ABCDEF0.1234");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x123456789ABCDEF0ULL, 0x1234ULL));
+
+  ex.Reset("p123456789ABCDEF0.123456789ABCDEF0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x123456789ABCDEF0ULL, 0x123456789ABCDEF0ULL));
+
+  ex.Reset("p123456789ABCDEF0.123456789ABCDEF0");
+  EXPECT_THAT(ex.GetPidTid(),
+              ::testing::Pair(0x123456789ABCDEF0ULL, 0x123456789ABCDEF0ULL));
+}