commit 7ecd60bb7022bb681b9dc01a9c232fd93b4b169c
Author: Evgenii Stepanov <eugenis@google.com>
Date:   Mon Oct 19 15:53:34 2020 -0700

    Revert "[Sanitizers] Remove OpenBSD support" + 1
    
    Revert "Fix compiler-rt build on Windows after D89640"
    
    This reverts commit a7acee89d68473183cc5021d952a56cdf0ae27d3.
    This reverts commit d09b08919ca6e206cd981fdea8b19b1d1188e325.
    
    Reason: breaks Linux / x86_64 build.

diff --git a/compiler-rt/cmake/base-config-ix.cmake b/compiler-rt/cmake/base-config-ix.cmake
index b273acd1816..a4c29d2943c 100644
--- a/compiler-rt/cmake/base-config-ix.cmake
+++ b/compiler-rt/cmake/base-config-ix.cmake
@@ -169,7 +169,18 @@ macro(test_targets)
     if(COMPILER_RT_DEFAULT_TARGET_ONLY)
       add_default_target_arch(${COMPILER_RT_DEFAULT_TARGET_ARCH})
     elseif("${COMPILER_RT_DEFAULT_TARGET_ARCH}" MATCHES "i[2-6]86|x86|amd64")
-      if(MSVC)
+      if(NOT MSVC)
+        if(CMAKE_SYSTEM_NAME MATCHES "OpenBSD")
+          if (CMAKE_SIZEOF_VOID_P EQUAL 4)
+            test_target_arch(i386 __i386__ "-m32")
+          else()
+            test_target_arch(x86_64 "" "-m64")
+          endif()
+        else()
+          test_target_arch(x86_64 "" "-m64")
+          test_target_arch(i386 __i386__ "-m32")
+        endif()
+      else()
         if (CMAKE_SIZEOF_VOID_P EQUAL 4)
           test_target_arch(i386 "" "")
         else()
diff --git a/compiler-rt/cmake/config-ix.cmake b/compiler-rt/cmake/config-ix.cmake
index 38a1a2bdfac..dd49544a476 100644
--- a/compiler-rt/cmake/config-ix.cmake
+++ b/compiler-rt/cmake/config-ix.cmake
@@ -644,7 +644,7 @@ set(COMPILER_RT_SANITIZERS_TO_BUILD all CACHE STRING
 list_replace(COMPILER_RT_SANITIZERS_TO_BUILD all "${ALL_SANITIZERS}")
 
 if (SANITIZER_COMMON_SUPPORTED_ARCH AND NOT LLVM_USE_SANITIZER AND
-    (OS_NAME MATCHES "Android|Darwin|Linux|FreeBSD|NetBSD|Fuchsia|SunOS" OR
+    (OS_NAME MATCHES "Android|Darwin|Linux|FreeBSD|NetBSD|OpenBSD|Fuchsia|SunOS" OR
     (OS_NAME MATCHES "Windows" AND NOT CYGWIN AND
         (NOT MINGW OR CMAKE_CXX_COMPILER_ID MATCHES "Clang"))))
   set(COMPILER_RT_HAS_SANITIZER_COMMON TRUE)
@@ -658,7 +658,8 @@ else()
   set(COMPILER_RT_HAS_INTERCEPTION FALSE)
 endif()
 
-if (COMPILER_RT_HAS_SANITIZER_COMMON AND ASAN_SUPPORTED_ARCH)
+if (COMPILER_RT_HAS_SANITIZER_COMMON AND ASAN_SUPPORTED_ARCH AND
+    NOT OS_NAME MATCHES "OpenBSD")
   set(COMPILER_RT_HAS_ASAN TRUE)
 else()
   set(COMPILER_RT_HAS_ASAN FALSE)
@@ -728,14 +729,14 @@ else()
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND UBSAN_SUPPORTED_ARCH AND
-    OS_NAME MATCHES "Darwin|Linux|FreeBSD|NetBSD|Windows|Android|Fuchsia|SunOS")
+    OS_NAME MATCHES "Darwin|Linux|FreeBSD|NetBSD|OpenBSD|Windows|Android|Fuchsia|SunOS")
   set(COMPILER_RT_HAS_UBSAN TRUE)
 else()
   set(COMPILER_RT_HAS_UBSAN FALSE)
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND UBSAN_SUPPORTED_ARCH AND
-    OS_NAME MATCHES "Linux|FreeBSD|NetBSD|Android|Darwin")
+    OS_NAME MATCHES "Linux|FreeBSD|NetBSD|OpenBSD|Android|Darwin")
   set(COMPILER_RT_HAS_UBSAN_MINIMAL TRUE)
 else()
   set(COMPILER_RT_HAS_UBSAN_MINIMAL FALSE)
@@ -770,14 +771,14 @@ else()
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND XRAY_SUPPORTED_ARCH AND
-    OS_NAME MATCHES "Darwin|Linux|FreeBSD|NetBSD|Fuchsia")
+    OS_NAME MATCHES "Darwin|Linux|FreeBSD|NetBSD|OpenBSD|Fuchsia")
   set(COMPILER_RT_HAS_XRAY TRUE)
 else()
   set(COMPILER_RT_HAS_XRAY FALSE)
 endif()
 
 if (COMPILER_RT_HAS_SANITIZER_COMMON AND FUZZER_SUPPORTED_ARCH AND
-    OS_NAME MATCHES "Android|Darwin|Linux|NetBSD|FreeBSD|Fuchsia|Windows")
+    OS_NAME MATCHES "Android|Darwin|Linux|NetBSD|FreeBSD|OpenBSD|Fuchsia|Windows")
   set(COMPILER_RT_HAS_FUZZER TRUE)
 else()
   set(COMPILER_RT_HAS_FUZZER FALSE)
diff --git a/compiler-rt/lib/asan/tests/asan_mem_test.cpp b/compiler-rt/lib/asan/tests/asan_mem_test.cpp
index e2af1b8d79a..5007d552bff 100644
--- a/compiler-rt/lib/asan/tests/asan_mem_test.cpp
+++ b/compiler-rt/lib/asan/tests/asan_mem_test.cpp
@@ -245,7 +245,7 @@ TEST(AddressSanitizer, MemCmpOOBTest) { CmpOOBTestCommon<memcmp>(); }
 
 TEST(AddressSanitizer, BCmpOOBTest) {
 #if (defined(__linux__) && !defined(__ANDROID__) && defined(_GNU_SOURCE)) || \
-    defined(__NetBSD__) || defined(__FreeBSD__)
+    defined(__NetBSD__) || defined(__FreeBSD__) || defined(__OpenBSD__)
   CmpOOBTestCommon<bcmp>();
 #endif
 }
diff --git a/compiler-rt/lib/fuzzer/FuzzerExtFunctionsWeak.cpp b/compiler-rt/lib/fuzzer/FuzzerExtFunctionsWeak.cpp
index 3ef758daa7b..24ddc57d47d 100644
--- a/compiler-rt/lib/fuzzer/FuzzerExtFunctionsWeak.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerExtFunctionsWeak.cpp
@@ -13,7 +13,7 @@
 //===----------------------------------------------------------------------===//
 #include "FuzzerPlatform.h"
 #if LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FUCHSIA ||                \
-    LIBFUZZER_FREEBSD || LIBFUZZER_EMSCRIPTEN
+    LIBFUZZER_FREEBSD || LIBFUZZER_OPENBSD || LIBFUZZER_EMSCRIPTEN
 
 #include "FuzzerExtFunctions.h"
 #include "FuzzerIO.h"
diff --git a/compiler-rt/lib/fuzzer/FuzzerExtraCounters.cpp b/compiler-rt/lib/fuzzer/FuzzerExtraCounters.cpp
index 04f569a1a87..d36beba1b1b 100644
--- a/compiler-rt/lib/fuzzer/FuzzerExtraCounters.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerExtraCounters.cpp
@@ -12,7 +12,7 @@
 #include <cstdint>
 
 #if LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FREEBSD ||                \
-    LIBFUZZER_FUCHSIA || LIBFUZZER_EMSCRIPTEN
+    LIBFUZZER_OPENBSD || LIBFUZZER_FUCHSIA || LIBFUZZER_EMSCRIPTEN
 __attribute__((weak)) extern uint8_t __start___libfuzzer_extra_counters;
 __attribute__((weak)) extern uint8_t __stop___libfuzzer_extra_counters;
 
diff --git a/compiler-rt/lib/fuzzer/FuzzerPlatform.h b/compiler-rt/lib/fuzzer/FuzzerPlatform.h
index 1602e678950..8befdb882cc 100644
--- a/compiler-rt/lib/fuzzer/FuzzerPlatform.h
+++ b/compiler-rt/lib/fuzzer/FuzzerPlatform.h
@@ -18,6 +18,7 @@
 #define LIBFUZZER_LINUX 1
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #define LIBFUZZER_WINDOWS 0
 #define LIBFUZZER_EMSCRIPTEN 0
 #elif __APPLE__
@@ -26,6 +27,7 @@
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #define LIBFUZZER_WINDOWS 0
 #define LIBFUZZER_EMSCRIPTEN 0
 #elif __NetBSD__
@@ -34,6 +36,7 @@
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_NETBSD 1
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #define LIBFUZZER_WINDOWS 0
 #define LIBFUZZER_EMSCRIPTEN 0
 #elif __FreeBSD__
@@ -42,6 +45,16 @@
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 1
+#define LIBFUZZER_OPENBSD 0
+#define LIBFUZZER_WINDOWS 0
+#define LIBFUZZER_EMSCRIPTEN 0
+#elif __OpenBSD__
+#define LIBFUZZER_APPLE 0
+#define LIBFUZZER_FUCHSIA 0
+#define LIBFUZZER_LINUX 0
+#define LIBFUZZER_NETBSD 0
+#define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 1
 #define LIBFUZZER_WINDOWS 0
 #define LIBFUZZER_EMSCRIPTEN 0
 #elif _WIN32
@@ -50,6 +63,7 @@
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #define LIBFUZZER_WINDOWS 1
 #define LIBFUZZER_EMSCRIPTEN 0
 #elif __Fuchsia__
@@ -58,6 +72,7 @@
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #define LIBFUZZER_WINDOWS 0
 #define LIBFUZZER_EMSCRIPTEN 0
 #elif __EMSCRIPTEN__
@@ -66,6 +81,7 @@
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #define LIBFUZZER_WINDOWS 0
 #define LIBFUZZER_EMSCRIPTEN 1
 #else
@@ -85,7 +101,7 @@
 
 #define LIBFUZZER_POSIX                                                        \
   (LIBFUZZER_APPLE || LIBFUZZER_LINUX || LIBFUZZER_NETBSD ||                   \
-   LIBFUZZER_FREEBSD || LIBFUZZER_EMSCRIPTEN)
+   LIBFUZZER_FREEBSD || LIBFUZZER_OPENBSD || LIBFUZZER_EMSCRIPTEN)
 
 #ifdef __x86_64
 #if __has_attribute(target)
diff --git a/compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp b/compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp
index 981f9a8b429..95490b992e0 100644
--- a/compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerUtilLinux.cpp
@@ -9,7 +9,7 @@
 //===----------------------------------------------------------------------===//
 #include "FuzzerPlatform.h"
 #if LIBFUZZER_LINUX || LIBFUZZER_NETBSD || LIBFUZZER_FREEBSD ||                \
-    LIBFUZZER_EMSCRIPTEN
+    LIBFUZZER_OPENBSD || LIBFUZZER_EMSCRIPTEN
 #include "FuzzerCommand.h"
 
 #include <stdlib.h>
diff --git a/compiler-rt/lib/fuzzer/FuzzerUtilPosix.cpp b/compiler-rt/lib/fuzzer/FuzzerUtilPosix.cpp
index afb733409ab..27ce69acb51 100644
--- a/compiler-rt/lib/fuzzer/FuzzerUtilPosix.cpp
+++ b/compiler-rt/lib/fuzzer/FuzzerUtilPosix.cpp
@@ -148,7 +148,7 @@ size_t GetPeakRSSMb() {
   if (getrusage(RUSAGE_SELF, &usage))
     return 0;
   if (LIBFUZZER_LINUX || LIBFUZZER_FREEBSD || LIBFUZZER_NETBSD ||
-      LIBFUZZER_EMSCRIPTEN) {
+      LIBFUZZER_OPENBSD || LIBFUZZER_EMSCRIPTEN) {
     // ru_maxrss is in KiB
     return usage.ru_maxrss >> 10;
   } else if (LIBFUZZER_APPLE) {
diff --git a/compiler-rt/lib/fuzzer/afl/afl_driver.cpp b/compiler-rt/lib/fuzzer/afl/afl_driver.cpp
index 52aede7e078..457f180ecc8 100644
--- a/compiler-rt/lib/fuzzer/afl/afl_driver.cpp
+++ b/compiler-rt/lib/fuzzer/afl/afl_driver.cpp
@@ -60,21 +60,31 @@ If 1, close stdout at startup. If 2 close stderr; if 3 close both.
 #define LIBFUZZER_APPLE 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #elif __APPLE__
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_APPLE 1
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #elif __NetBSD__
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_APPLE 0
 #define LIBFUZZER_NETBSD 1
 #define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 0
 #elif __FreeBSD__
 #define LIBFUZZER_LINUX 0
 #define LIBFUZZER_APPLE 0
 #define LIBFUZZER_NETBSD 0
 #define LIBFUZZER_FREEBSD 1
+#define LIBFUZZER_OPENBSD 0
+#elif __OpenBSD__
+#define LIBFUZZER_LINUX 0
+#define LIBFUZZER_APPLE 0
+#define LIBFUZZER_NETBSD 0
+#define LIBFUZZER_FREEBSD 0
+#define LIBFUZZER_OPENBSD 1
 #else
 #error "Support for your platform has not been implemented"
 #endif
diff --git a/compiler-rt/lib/interception/interception.h b/compiler-rt/lib/interception/interception.h
index cb0b5284ed2..d27a8ccf92a 100644
--- a/compiler-rt/lib/interception/interception.h
+++ b/compiler-rt/lib/interception/interception.h
@@ -17,7 +17,7 @@
 #include "sanitizer_common/sanitizer_internal_defs.h"
 
 #if !SANITIZER_LINUX && !SANITIZER_FREEBSD && !SANITIZER_MAC && \
-    !SANITIZER_NETBSD && !SANITIZER_WINDOWS && \
+    !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_WINDOWS && \
     !SANITIZER_FUCHSIA && !SANITIZER_RTEMS && !SANITIZER_SOLARIS
 # error "Interception doesn't work on this operating system."
 #endif
@@ -281,7 +281,7 @@ typedef unsigned long uptr;
 #define INCLUDED_FROM_INTERCEPTION_LIB
 
 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
 
 # include "interception_linux.h"
 # define INTERCEPT_FUNCTION(func) INTERCEPT_FUNCTION_LINUX_OR_FREEBSD(func)
diff --git a/compiler-rt/lib/interception/interception_linux.cpp b/compiler-rt/lib/interception/interception_linux.cpp
index 6883608d44f..950cd512653 100644
--- a/compiler-rt/lib/interception/interception_linux.cpp
+++ b/compiler-rt/lib/interception/interception_linux.cpp
@@ -14,7 +14,7 @@
 #include "interception.h"
 
 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
 
 #include <dlfcn.h>   // for dlsym() and dlvsym()
 
@@ -64,7 +64,7 @@ bool InterceptFunction(const char *name, uptr *ptr_to_real, uptr func,
 }
 
 // Android and Solaris do not have dlvsym
-#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS
+#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD
 static void *GetFuncAddr(const char *name, const char *ver) {
   return dlvsym(RTLD_NEXT, name, ver);
 }
@@ -80,4 +80,4 @@ bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
 }  // namespace __interception
 
 #endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
-        // SANITIZER_SOLARIS
+        // SANITIZER_OPENBSD || SANITIZER_SOLARIS
diff --git a/compiler-rt/lib/interception/interception_linux.h b/compiler-rt/lib/interception/interception_linux.h
index 097375fd1c1..e578da0cf64 100644
--- a/compiler-rt/lib/interception/interception_linux.h
+++ b/compiler-rt/lib/interception/interception_linux.h
@@ -12,7 +12,7 @@
 //===----------------------------------------------------------------------===//
 
 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
 
 #if !defined(INCLUDED_FROM_INTERCEPTION_LIB)
 # error "interception_linux.h should be included from interception library only"
@@ -35,8 +35,8 @@ bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
       (::__interception::uptr) & (func),          \
       (::__interception::uptr) & WRAP(func))
 
-// Android and Solaris do not have dlvsym
-#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS
+// Android,  Solaris and OpenBSD do not have dlvsym
+#if !SANITIZER_ANDROID && !SANITIZER_SOLARIS && !SANITIZER_OPENBSD
 #define INTERCEPT_FUNCTION_VER_LINUX_OR_FREEBSD(func, symver) \
   ::__interception::InterceptFunction(                        \
       #func, symver,                                          \
@@ -50,4 +50,4 @@ bool InterceptFunction(const char *name, const char *ver, uptr *ptr_to_real,
 
 #endif  // INTERCEPTION_LINUX_H
 #endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
-        // SANITIZER_SOLARIS
+        // SANITIZER_OPENBSD || SANITIZER_SOLARIS
diff --git a/compiler-rt/lib/sanitizer_common/CMakeLists.txt b/compiler-rt/lib/sanitizer_common/CMakeLists.txt
index 674835aba12..3ac13f6a64d 100644
--- a/compiler-rt/lib/sanitizer_common/CMakeLists.txt
+++ b/compiler-rt/lib/sanitizer_common/CMakeLists.txt
@@ -17,10 +17,12 @@ set(SANITIZER_SOURCES_NOTERMINATION
   sanitizer_linux_s390.cpp
   sanitizer_mac.cpp
   sanitizer_netbsd.cpp
+  sanitizer_openbsd.cpp
   sanitizer_persistent_allocator.cpp
   sanitizer_platform_limits_freebsd.cpp
   sanitizer_platform_limits_linux.cpp
   sanitizer_platform_limits_netbsd.cpp
+  sanitizer_platform_limits_openbsd.cpp
   sanitizer_platform_limits_posix.cpp
   sanitizer_platform_limits_solaris.cpp
   sanitizer_posix.cpp
@@ -157,6 +159,7 @@ set(SANITIZER_IMPL_HEADERS
   sanitizer_platform.h
   sanitizer_platform_interceptors.h
   sanitizer_platform_limits_netbsd.h
+  sanitizer_platform_limits_openbsd.h
   sanitizer_platform_limits_posix.h
   sanitizer_platform_limits_solaris.h
   sanitizer_posix.h
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
index 729eead43c0..5b510781d40 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_common_interceptors.inc
@@ -1864,7 +1864,7 @@ UNUSED static void unpoison_passwd(void *ctx, __sanitizer_passwd *pwd) {
       COMMON_INTERCEPTOR_WRITE_RANGE(ctx, pwd->pw_gecos,
                                      REAL(strlen)(pwd->pw_gecos) + 1);
 #endif
-#if SANITIZER_MAC || SANITIZER_FREEBSD || SANITIZER_NETBSD
+#if SANITIZER_MAC || SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD
     if (pwd->pw_class)
       COMMON_INTERCEPTOR_WRITE_RANGE(ctx, pwd->pw_class,
                                      REAL(strlen)(pwd->pw_class) + 1);
@@ -3750,7 +3750,7 @@ INTERCEPTOR(char *, strerror, int errnum) {
 //    static storage.
 #if ((_POSIX_C_SOURCE >= 200112L || _XOPEN_SOURCE >= 600) && !_GNU_SOURCE) || \
     SANITIZER_MAC || SANITIZER_ANDROID || SANITIZER_NETBSD ||                 \
-    SANITIZER_FREEBSD
+    SANITIZER_FREEBSD || SANITIZER_OPENBSD
 // POSIX version. Spec is not clear on whether buf is NULL-terminated.
 // At least on OSX, buf contents are valid even when the call fails.
 INTERCEPTOR(int, strerror_r, int errnum, char *buf, SIZE_T buflen) {
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_errno.h b/compiler-rt/lib/sanitizer_common/sanitizer_errno.h
index 94f16b6e873..584e66e4a86 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_errno.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_errno.h
@@ -23,7 +23,7 @@
 
 #if SANITIZER_FREEBSD || SANITIZER_MAC
 #  define __errno_location __error
-#elif SANITIZER_ANDROID || SANITIZER_NETBSD || \
+#elif SANITIZER_ANDROID || SANITIZER_NETBSD || SANITIZER_OPENBSD || \
   SANITIZER_RTEMS
 #  define __errno_location __errno
 #elif SANITIZER_SOLARIS
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
index 26a7d615d8b..8b34e54137d 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_internal_defs.h
@@ -39,7 +39,7 @@
 
 // TLS is handled differently on different platforms
 #if SANITIZER_LINUX || SANITIZER_NETBSD || \
-  SANITIZER_FREEBSD
+  SANITIZER_FREEBSD || SANITIZER_OPENBSD
 # define SANITIZER_TLS_INITIAL_EXEC_ATTRIBUTE \
     __attribute__((tls_model("initial-exec"))) thread_local
 #else
@@ -104,7 +104,7 @@
 //
 // FIXME: do we have anything like this on Mac?
 #ifndef SANITIZER_CAN_USE_PREINIT_ARRAY
-#if ((SANITIZER_LINUX && !SANITIZER_ANDROID) || \
+#if ((SANITIZER_LINUX && !SANITIZER_ANDROID) || SANITIZER_OPENBSD || \
      SANITIZER_FUCHSIA || SANITIZER_NETBSD) && !defined(PIC)
 #define SANITIZER_CAN_USE_PREINIT_ARRAY 1
 // Before Solaris 11.4, .preinit_array is fully supported only with GNU ld.
@@ -170,7 +170,7 @@ typedef int pid_t;
 #endif
 
 #if SANITIZER_FREEBSD || SANITIZER_NETBSD || \
-    SANITIZER_MAC || \
+    SANITIZER_OPENBSD || SANITIZER_MAC || \
     (SANITIZER_SOLARIS && (defined(_LP64) || _FILE_OFFSET_BITS == 64)) || \
     (SANITIZER_LINUX && defined(__x86_64__))
 typedef u64 OFF_T;
@@ -182,7 +182,7 @@ typedef u64  OFF64_T;
 #if (SANITIZER_WORDSIZE == 64) || SANITIZER_MAC
 typedef uptr operator_new_size_type;
 #else
-# if defined(__s390__) && !defined(__s390x__)
+# if SANITIZER_OPENBSD || defined(__s390__) && !defined(__s390x__)
 // Special case: 31-bit s390 has unsigned long as size_t.
 typedef unsigned long operator_new_size_type;
 # else
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp
index 9ea19bc21fa..eb9bb765013 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_libignore.cpp
@@ -9,7 +9,7 @@
 #include "sanitizer_platform.h"
 
 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_MAC || \
-    SANITIZER_NETBSD
+    SANITIZER_NETBSD || SANITIZER_OPENBSD
 
 #include "sanitizer_libignore.h"
 #include "sanitizer_flags.h"
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
index 024bef3c058..c84946ca9bf 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux.cpp
@@ -14,7 +14,7 @@
 #include "sanitizer_platform.h"
 
 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
 
 #include "sanitizer_common.h"
 #include "sanitizer_flags.h"
@@ -59,7 +59,13 @@
 #include <sys/syscall.h>
 #include <sys/time.h>
 #include <sys/types.h>
+#if !SANITIZER_OPENBSD
 #include <ucontext.h>
+#endif
+#if SANITIZER_OPENBSD
+#include <sys/futex.h>
+#include <sys/sysctl.h>
+#endif
 #include <unistd.h>
 
 #if SANITIZER_LINUX
@@ -123,7 +129,7 @@ const int FUTEX_WAKE_PRIVATE = FUTEX_WAKE | FUTEX_PRIVATE_FLAG;
 #endif
 
 // Note : FreeBSD had implemented both
-// Linux apis, available from
+// Linux and OpenBSD apis, available from
 // future 12.x version most likely
 #if SANITIZER_LINUX && defined(__NR_getrandom)
 # if !defined(GRND_NONBLOCK)
@@ -134,11 +140,15 @@ const int FUTEX_WAKE_PRIVATE = FUTEX_WAKE | FUTEX_PRIVATE_FLAG;
 # define SANITIZER_USE_GETRANDOM 0
 #endif  // SANITIZER_LINUX && defined(__NR_getrandom)
 
-#if SANITIZER_FREEBSD && __FreeBSD_version >= 1200000
-#  define SANITIZER_USE_GETENTROPY 1
+#if SANITIZER_OPENBSD
+# define SANITIZER_USE_GETENTROPY 1
 #else
-#  define SANITIZER_USE_GETENTROPY 0
-#endif
+# if SANITIZER_FREEBSD && __FreeBSD_version >= 1200000
+#   define SANITIZER_USE_GETENTROPY 1
+# else
+#   define SANITIZER_USE_GETENTROPY 0
+# endif
+#endif // SANITIZER_USE_GETENTROPY
 
 namespace __sanitizer {
 
@@ -156,7 +166,7 @@ namespace __sanitizer {
 
 // --------------- sanitizer_libc.h
 #if !SANITIZER_SOLARIS && !SANITIZER_NETBSD
-#if !SANITIZER_S390
+#if !SANITIZER_S390 && !SANITIZER_OPENBSD
 uptr internal_mmap(void *addr, uptr length, int prot, int flags, int fd,
                    u64 offset) {
 #if SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
@@ -169,8 +179,9 @@ uptr internal_mmap(void *addr, uptr length, int prot, int flags, int fd,
                           offset / 4096);
 #endif
 }
-#endif // !SANITIZER_S390
+#endif // !SANITIZER_S390 && !SANITIZER_OPENBSD
 
+#if !SANITIZER_OPENBSD
 uptr internal_munmap(void *addr, uptr length) {
   return internal_syscall(SYSCALL(munmap), (uptr)addr, length);
 }
@@ -182,6 +193,7 @@ int internal_mprotect(void *addr, uptr length, int prot) {
 int internal_madvise(uptr addr, uptr length, int advice) {
   return internal_syscall(SYSCALL(madvise), addr, length, advice);
 }
+#endif
 
 uptr internal_close(fd_t fd) {
   return internal_syscall(SYSCALL(close), fd);
@@ -293,7 +305,7 @@ static void kernel_stat_to_stat(struct kernel_stat *in, struct stat *out) {
 #endif
 
 uptr internal_stat(const char *path, void *buf) {
-#if SANITIZER_FREEBSD
+#if SANITIZER_FREEBSD || SANITIZER_OPENBSD
   return internal_syscall(SYSCALL(fstatat), AT_FDCWD, (uptr)path, (uptr)buf, 0);
 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
   return internal_syscall(SYSCALL(newfstatat), AT_FDCWD, (uptr)path, (uptr)buf,
@@ -317,7 +329,7 @@ uptr internal_stat(const char *path, void *buf) {
 }
 
 uptr internal_lstat(const char *path, void *buf) {
-#if SANITIZER_FREEBSD
+#if SANITIZER_FREEBSD || SANITIZER_OPENBSD
   return internal_syscall(SYSCALL(fstatat), AT_FDCWD, (uptr)path, (uptr)buf,
                           AT_SYMLINK_NOFOLLOW);
 #elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
@@ -342,8 +354,9 @@ uptr internal_lstat(const char *path, void *buf) {
 }
 
 uptr internal_fstat(fd_t fd, void *buf) {
-#if SANITIZER_FREEBSD || SANITIZER_LINUX_USES_64BIT_SYSCALLS
-#if SANITIZER_MIPS64
+#if SANITIZER_FREEBSD || SANITIZER_OPENBSD || \
+    SANITIZER_LINUX_USES_64BIT_SYSCALLS
+#if SANITIZER_MIPS64 && !SANITIZER_OPENBSD
   // For mips64, fstat syscall fills buffer in the format of kernel_stat
   struct kernel_stat kbuf;
   int res = internal_syscall(SYSCALL(fstat), fd, &kbuf);
@@ -383,13 +396,16 @@ uptr internal_readlink(const char *path, char *buf, uptr bufsize) {
 #if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
   return internal_syscall(SYSCALL(readlinkat), AT_FDCWD, (uptr)path, (uptr)buf,
                           bufsize);
+#elif SANITIZER_OPENBSD
+  return internal_syscall(SYSCALL(readlinkat), AT_FDCWD, (uptr)path, (uptr)buf,
+                          bufsize);
 #else
   return internal_syscall(SYSCALL(readlink), (uptr)path, (uptr)buf, bufsize);
 #endif
 }
 
 uptr internal_unlink(const char *path) {
-#if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
+#if SANITIZER_USES_CANONICAL_LINUX_SYSCALLS || SANITIZER_OPENBSD
   return internal_syscall(SYSCALL(unlinkat), AT_FDCWD, (uptr)path, 0);
 #else
   return internal_syscall(SYSCALL(unlink), (uptr)path);
@@ -400,7 +416,7 @@ uptr internal_rename(const char *oldpath, const char *newpath) {
 #if defined(__riscv)
   return internal_syscall(SYSCALL(renameat2), AT_FDCWD, (uptr)oldpath, AT_FDCWD,
                           (uptr)newpath, 0);
-#elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS
+#elif SANITIZER_USES_CANONICAL_LINUX_SYSCALLS || SANITIZER_OPENBSD
   return internal_syscall(SYSCALL(renameat), AT_FDCWD, (uptr)oldpath, AT_FDCWD,
                           (uptr)newpath);
 #else
@@ -430,7 +446,7 @@ uptr internal_execve(const char *filename, char *const argv[],
 
 #if !SANITIZER_NETBSD
 void internal__exit(int exitcode) {
-#if SANITIZER_FREEBSD || SANITIZER_SOLARIS
+#if SANITIZER_FREEBSD || SANITIZER_OPENBSD || SANITIZER_SOLARIS
   internal_syscall(SYSCALL(exit), exitcode);
 #else
   internal_syscall(SYSCALL(exit_group), exitcode);
@@ -460,6 +476,8 @@ tid_t GetTid() {
   long Tid;
   thr_self(&Tid);
   return Tid;
+#elif SANITIZER_OPENBSD
+  return internal_syscall(SYSCALL(getthrid));
 #elif SANITIZER_SOLARIS
   return thr_self();
 #else
@@ -472,6 +490,9 @@ int TgKill(pid_t pid, tid_t tid, int sig) {
   return internal_syscall(SYSCALL(tgkill), pid, tid, sig);
 #elif SANITIZER_FREEBSD
   return internal_syscall(SYSCALL(thr_kill2), pid, tid, sig);
+#elif SANITIZER_OPENBSD
+  (void)pid;
+  return internal_syscall(SYSCALL(thrkill), tid, sig, nullptr);
 #elif SANITIZER_SOLARIS
   (void)pid;
   return thr_kill(tid, sig);
@@ -481,7 +502,7 @@ int TgKill(pid_t pid, tid_t tid, int sig) {
 
 #if !SANITIZER_SOLARIS && !SANITIZER_NETBSD
 u64 NanoTime() {
-#if SANITIZER_FREEBSD
+#if SANITIZER_FREEBSD || SANITIZER_OPENBSD
   timeval tv;
 #else
   kernel_timeval tv;
@@ -500,7 +521,8 @@ uptr internal_clock_gettime(__sanitizer_clockid_t clk_id, void *tp) {
 // 'environ' array (on some others) and does not use libc. This function
 // should be called first inside __asan_init.
 const char *GetEnv(const char *name) {
-#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_SOLARIS
+#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD || \
+    SANITIZER_SOLARIS
   if (::environ != 0) {
     uptr NameLen = internal_strlen(name);
     for (char **Env = ::environ; *Env != 0; Env++) {
@@ -538,13 +560,15 @@ const char *GetEnv(const char *name) {
 #endif
 }
 
-#if !SANITIZER_FREEBSD && !SANITIZER_NETBSD && !SANITIZER_GO
+#if !SANITIZER_FREEBSD && !SANITIZER_NETBSD && !SANITIZER_OPENBSD && \
+    !SANITIZER_GO
 extern "C" {
 SANITIZER_WEAK_ATTRIBUTE extern void *__libc_stack_end;
 }
 #endif
 
-#if !SANITIZER_FREEBSD && !SANITIZER_NETBSD
+#if !SANITIZER_FREEBSD && !SANITIZER_NETBSD &&                \
+    !SANITIZER_OPENBSD
 static void ReadNullSepFileToArray(const char *path, char ***arr,
                                    int arr_size) {
   char *buff;
@@ -569,6 +593,7 @@ static void ReadNullSepFileToArray(const char *path, char ***arr,
 }
 #endif
 
+#if !SANITIZER_OPENBSD
 static void GetArgsAndEnv(char ***argv, char ***envp) {
 #if SANITIZER_FREEBSD
   // On FreeBSD, retrieving the argument and environment arrays is done via the
@@ -620,6 +645,8 @@ char **GetEnviron() {
   return envp;
 }
 
+#endif  // !SANITIZER_OPENBSD
+
 #if !SANITIZER_SOLARIS
 enum MutexState {
   MtxUnlocked = 0,
@@ -675,6 +702,16 @@ void BlockingMutex::CheckLocked() {
 // 32-bit syscall here.
 #if SANITIZER_NETBSD
 // Not used
+#elif SANITIZER_OPENBSD
+// struct dirent is different for Linux and us. At this moment, we use only
+// d_fileno (Linux call this d_ino), d_reclen, and d_name.
+struct linux_dirent {
+  u64 d_ino;  // d_fileno
+  u16 d_reclen;
+  u16 d_namlen;  // not used
+  u8 d_type;     // not used
+  char d_name[NAME_MAX + 1];
+};
 #else
 struct linux_dirent {
 #if SANITIZER_X32 || defined(__aarch64__) || SANITIZER_RISCV64
@@ -752,13 +789,19 @@ int internal_fork() {
 #endif
 }
 
-#if SANITIZER_FREEBSD
+#if SANITIZER_FREEBSD || SANITIZER_OPENBSD
 int internal_sysctl(const int *name, unsigned int namelen, void *oldp,
                     uptr *oldlenp, const void *newp, uptr newlen) {
+#if SANITIZER_OPENBSD
+  return sysctl(name, namelen, oldp, (size_t *)oldlenp, (void *)newp,
+                (size_t)newlen);
+#else
   return internal_syscall(SYSCALL(__sysctl), name, namelen, oldp,
                           (size_t *)oldlenp, newp, (size_t)newlen);
+#endif
 }
 
+#if SANITIZER_FREEBSD
 int internal_sysctlbyname(const char *sname, void *oldp, uptr *oldlenp,
                           const void *newp, uptr newlen) {
   // Note: this function can be called during startup, so we need to avoid
@@ -786,6 +829,7 @@ int internal_sysctlbyname(const char *sname, void *oldp, uptr *oldlenp,
 #endif
 }
 #endif
+#endif
 
 #if SANITIZER_LINUX
 #define SA_RESTORER 0x04000000
@@ -838,7 +882,7 @@ int internal_sigaction_norestorer(int signum, const void *act, void *oldact) {
 
 uptr internal_sigprocmask(int how, __sanitizer_sigset_t *set,
                           __sanitizer_sigset_t *oldset) {
-#if SANITIZER_FREEBSD
+#if SANITIZER_FREEBSD || SANITIZER_OPENBSD
   return internal_syscall(SYSCALL(sigprocmask), how, set, oldset);
 #else
   __sanitizer_kernel_sigset_t *k_set = (__sanitizer_kernel_sigset_t *)set;
@@ -1015,7 +1059,7 @@ static uptr GetKernelAreaSize() {
 #endif  // SANITIZER_WORDSIZE == 32
 
 uptr GetMaxVirtualAddress() {
-#if SANITIZER_NETBSD && defined(__x86_64__)
+#if (SANITIZER_NETBSD || SANITIZER_OPENBSD) && defined(__x86_64__)
   return 0x7f7ffffff000ULL;  // (0x00007f8000000000 - PAGE_SIZE)
 #elif SANITIZER_WORDSIZE == 64
 # if defined(__powerpc64__) || defined(__aarch64__)
@@ -1078,6 +1122,7 @@ uptr GetPageSize() {
 }
 #endif // !SANITIZER_ANDROID
 
+#if !SANITIZER_OPENBSD
 uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
 #if SANITIZER_SOLARIS
   const char *default_module_name = getexecname();
@@ -1114,6 +1159,7 @@ uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
   return module_name_len;
 #endif
 }
+#endif // !SANITIZER_OPENBSD
 
 uptr ReadLongProcessName(/*out*/ char *buf, uptr buf_len) {
 #if SANITIZER_LINUX
@@ -1146,10 +1192,10 @@ bool LibraryNameIs(const char *full_name, const char *base_name) {
 // Call cb for each region mapped by map.
 void ForEachMappedRegion(link_map *map, void (*cb)(const void *, uptr)) {
   CHECK_NE(map, nullptr);
-#if !SANITIZER_FREEBSD
+#if !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
   typedef ElfW(Phdr) Elf_Phdr;
   typedef ElfW(Ehdr) Elf_Ehdr;
-#endif // !SANITIZER_FREEBSD
+#endif // !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
   char *base = (char *)map->l_addr;
   Elf_Ehdr *ehdr = (Elf_Ehdr *)base;
   char *phdrs = base + ehdr->e_phoff;
@@ -1799,7 +1845,11 @@ static bool Aarch64GetESR(ucontext_t *ucontext, u64 *esr) {
 }
 #endif
 
+#if SANITIZER_OPENBSD
+using Context = sigcontext;
+#else
 using Context = ucontext_t;
+#endif
 
 SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
   Context *ucontext = (Context *)context;
@@ -1809,6 +1859,8 @@ SignalContext::WriteFlag SignalContext::GetWriteFlag() const {
   uptr err = ucontext->uc_mcontext.mc_err;
 #elif SANITIZER_NETBSD
   uptr err = ucontext->uc_mcontext.__gregs[_REG_ERR];
+#elif SANITIZER_OPENBSD
+  uptr err = ucontext->sc_err;
 #elif SANITIZER_SOLARIS && defined(__i386__)
   const int Err = 13;
   uptr err = ucontext->uc_mcontext.gregs[Err];
@@ -2034,6 +2086,11 @@ static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   *pc = ucontext->uc_mcontext.mc_rip;
   *bp = ucontext->uc_mcontext.mc_rbp;
   *sp = ucontext->uc_mcontext.mc_rsp;
+#elif SANITIZER_OPENBSD
+  sigcontext *ucontext = (sigcontext *)context;
+  *pc = ucontext->sc_rip;
+  *bp = ucontext->sc_rbp;
+  *sp = ucontext->sc_rsp;
 # else
   ucontext_t *ucontext = (ucontext_t*)context;
   *pc = ucontext->uc_mcontext.gregs[REG_RIP];
@@ -2046,6 +2103,11 @@ static void GetPcSpBp(void *context, uptr *pc, uptr *sp, uptr *bp) {
   *pc = ucontext->uc_mcontext.mc_eip;
   *bp = ucontext->uc_mcontext.mc_ebp;
   *sp = ucontext->uc_mcontext.mc_esp;
+#elif SANITIZER_OPENBSD
+  sigcontext *ucontext = (sigcontext *)context;
+  *pc = ucontext->sc_eip;
+  *bp = ucontext->sc_ebp;
+  *sp = ucontext->sc_esp;
 # else
   ucontext_t *ucontext = (ucontext_t*)context;
 # if SANITIZER_SOLARIS
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux.h b/compiler-rt/lib/sanitizer_common/sanitizer_linux.h
index 24902d1b6bc..a8625ca86e8 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux.h
@@ -14,11 +14,12 @@
 
 #include "sanitizer_platform.h"
 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||                \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
 #include "sanitizer_common.h"
 #include "sanitizer_internal_defs.h"
 #include "sanitizer_platform_limits_freebsd.h"
 #include "sanitizer_platform_limits_netbsd.h"
+#include "sanitizer_platform_limits_openbsd.h"
 #include "sanitizer_platform_limits_posix.h"
 #include "sanitizer_platform_limits_solaris.h"
 #include "sanitizer_posix.h"
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
index 10627549704..ecfa38b951c 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_linux_libcdep.cpp
@@ -14,7 +14,7 @@
 #include "sanitizer_platform.h"
 
 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD || \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
 
 #include "sanitizer_allocator_internal.h"
 #include "sanitizer_atomic.h"
@@ -50,6 +50,11 @@
 #define pthread_getattr_np pthread_attr_get_np
 #endif
 
+#if SANITIZER_OPENBSD
+#include <pthread_np.h>
+#include <sys/sysctl.h>
+#endif
+
 #if SANITIZER_NETBSD
 #include <sys/sysctl.h>
 #include <sys/tls.h>
@@ -137,6 +142,11 @@ void GetThreadStackTopAndBottom(bool at_initialization, uptr *stack_top,
   CHECK_EQ(thr_stksegment(&ss), 0);
   stacksize = ss.ss_size;
   stackaddr = (char *)ss.ss_sp - stacksize;
+#elif SANITIZER_OPENBSD
+  stack_t sattr;
+  CHECK_EQ(pthread_stackseg_np(pthread_self(), &sattr), 0);
+  stackaddr = sattr.ss_sp;
+  stacksize = sattr.ss_size;
 #else  // !SANITIZER_SOLARIS
   pthread_attr_t attr;
   pthread_attr_init(&attr);
@@ -184,7 +194,7 @@ __attribute__((unused)) static bool GetLibcVersion(int *major, int *minor,
 }
 
 #if !SANITIZER_FREEBSD && !SANITIZER_ANDROID && !SANITIZER_GO && \
-    !SANITIZER_NETBSD && !SANITIZER_SOLARIS
+    !SANITIZER_NETBSD && !SANITIZER_OPENBSD && !SANITIZER_SOLARIS
 static uptr g_tls_size;
 
 #ifdef __i386__
@@ -488,6 +498,9 @@ static void GetTls(uptr *addr, uptr *size) {
       *addr = (uptr)tcb->tcb_dtv[1];
     }
   }
+#elif SANITIZER_OPENBSD
+  *addr = 0;
+  *size = 0;
 #elif SANITIZER_ANDROID
   *addr = 0;
   *size = 0;
@@ -504,7 +517,7 @@ static void GetTls(uptr *addr, uptr *size) {
 #if !SANITIZER_GO
 uptr GetTlsSize() {
 #if SANITIZER_FREEBSD || SANITIZER_ANDROID || SANITIZER_NETBSD || \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
   uptr addr, size;
   GetTls(&addr, &size);
   return size;
@@ -541,13 +554,13 @@ void GetThreadStackAndTls(bool main, uptr *stk_addr, uptr *stk_size,
 #endif
 }
 
-#if !SANITIZER_FREEBSD
+#if !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
 typedef ElfW(Phdr) Elf_Phdr;
 #elif SANITIZER_WORDSIZE == 32 && __FreeBSD_version <= 902001  // v9.2
 #define Elf_Phdr XElf32_Phdr
 #define dl_phdr_info xdl_phdr_info
 #define dl_iterate_phdr(c, b) xdl_iterate_phdr((c), (b))
-#endif  // !SANITIZER_FREEBSD
+#endif  // !SANITIZER_FREEBSD && !SANITIZER_OPENBSD
 
 struct DlIteratePhdrData {
   InternalMmapVectorNoCtor<LoadedModule> *modules;
@@ -667,7 +680,7 @@ uptr GetRSS() {
 // sysconf(_SC_NPROCESSORS_{CONF,ONLN}) cannot be used on most platforms as
 // they allocate memory.
 u32 GetNumberOfCPUs() {
-#if SANITIZER_FREEBSD || SANITIZER_NETBSD
+#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD
   u32 ncpu;
   int req[2];
   uptr len = sizeof(ncpu);
@@ -824,6 +837,7 @@ u64 MonotonicNanoTime() {
 }
 #endif  // SANITIZER_LINUX && !SANITIZER_GO
 
+#if !SANITIZER_OPENBSD
 void ReExec() {
   const char *pathname = "/proc/self/exe";
 
@@ -855,6 +869,7 @@ void ReExec() {
   Printf("execve failed, errno %d\n", rverrno);
   Die();
 }
+#endif  // !SANITIZER_OPENBSD
 
 void UnmapFromTo(uptr from, uptr to) {
   if (to == from)
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_openbsd.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_openbsd.cpp
new file mode 100644
index 00000000000..195901714b1
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_openbsd.cpp
@@ -0,0 +1,119 @@
+//===-- sanitizer_openbsd.cpp ---------------------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is shared between various sanitizers' runtime libraries and
+// implements Solaris-specific functions.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+#if SANITIZER_OPENBSD
+
+#include <stdio.h>
+
+#include "sanitizer_common.h"
+#include "sanitizer_flags.h"
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_libc.h"
+#include "sanitizer_placement_new.h"
+#include "sanitizer_platform_limits_posix.h"
+#include "sanitizer_procmaps.h"
+
+#include <errno.h>
+#include <fcntl.h>
+#include <limits.h>
+#include <pthread.h>
+#include <sched.h>
+#include <signal.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/mman.h>
+#include <sys/shm.h>
+#include <sys/sysctl.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+extern char **environ;
+
+namespace __sanitizer {
+
+uptr internal_mmap(void *addr, size_t length, int prot, int flags, int fd,
+                   u64 offset) {
+  return (uptr)mmap(addr, length, prot, flags, fd, offset);
+}
+
+uptr internal_munmap(void *addr, uptr length) { return munmap(addr, length); }
+
+int internal_mprotect(void *addr, uptr length, int prot) {
+  return mprotect(addr, length, prot);
+}
+
+int internal_madvise(uptr addr, uptr length, int advice) {
+  return madvise((void *)addr, length, advice);
+}
+
+int internal_sysctlbyname(const char *sname, void *oldp, uptr *oldlenp,
+                          const void *newp, uptr newlen) {
+  Printf("internal_sysctlbyname not implemented for OpenBSD");
+  Die();
+  return 0;
+}
+
+uptr ReadBinaryName(/*out*/char *buf, uptr buf_len) {
+  // On OpenBSD we cannot get the full path
+  struct kinfo_proc kp;
+  uptr kl;
+  const int Mib[4] = {CTL_KERN, KERN_PROC, KERN_PROC_PID, getpid()};
+  if (internal_sysctl(Mib, ARRAY_SIZE(Mib), &kp, &kl, NULL, 0) != -1)
+    return internal_snprintf(buf,
+                             (KI_MAXCOMLEN < buf_len ? KI_MAXCOMLEN : buf_len),
+                             "%s", kp.p_comm);
+  return (uptr)0;
+}
+
+static void GetArgsAndEnv(char ***argv, char ***envp) {
+  uptr nargv;
+  uptr nenv;
+  int argvmib[4] = {CTL_KERN, KERN_PROC_ARGS, getpid(), KERN_PROC_ARGV};
+  int envmib[4] = {CTL_KERN, KERN_PROC_ARGS, getpid(), KERN_PROC_ENV};
+  if (internal_sysctl(argvmib, 4, NULL, &nargv, NULL, 0) == -1) {
+    Printf("sysctl KERN_PROC_NARGV failed\n");
+    Die();
+  }
+  if (internal_sysctl(envmib, 4, NULL, &nenv, NULL, 0) == -1) {
+    Printf("sysctl KERN_PROC_NENV failed\n");
+    Die();
+  }
+  if (internal_sysctl(argvmib, 4, &argv, &nargv, NULL, 0) == -1) {
+    Printf("sysctl KERN_PROC_ARGV failed\n");
+    Die();
+  }
+  if (internal_sysctl(envmib, 4, &envp, &nenv, NULL, 0) == -1) {
+    Printf("sysctl KERN_PROC_ENV failed\n");
+    Die();
+  }
+}
+
+char **GetArgv() {
+  char **argv, **envp;
+  GetArgsAndEnv(&argv, &envp);
+  return argv;
+}
+
+char **GetEnviron() {
+  char **argv, **envp;
+  GetArgsAndEnv(&argv, &envp);
+  return envp;
+}
+
+void ReExec() {
+  UNIMPLEMENTED();
+}
+
+}  // namespace __sanitizer
+
+#endif  // SANITIZER_OPENBSD
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform.h
index 657265f4942..5547c68bc51 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_platform.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform.h
@@ -13,7 +13,7 @@
 #define SANITIZER_PLATFORM_H
 
 #if !defined(__linux__) && !defined(__FreeBSD__) && !defined(__NetBSD__) && \
-  !defined(__APPLE__) && !defined(_WIN32) && \
+  !defined(__OpenBSD__) && !defined(__APPLE__) && !defined(_WIN32) && \
   !defined(__Fuchsia__) && !defined(__rtems__) && \
   !(defined(__sun__) && defined(__svr4__))
 # error "This operating system is not supported"
@@ -37,6 +37,12 @@
 # define SANITIZER_NETBSD 0
 #endif
 
+#if defined(__OpenBSD__)
+# define SANITIZER_OPENBSD 1
+#else
+# define SANITIZER_OPENBSD 0
+#endif
+
 #if defined(__sun__) && defined(__svr4__)
 # define SANITIZER_SOLARIS 1
 #else
@@ -106,7 +112,7 @@
 
 #define SANITIZER_POSIX \
   (SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_MAC || \
-    SANITIZER_NETBSD || SANITIZER_SOLARIS)
+    SANITIZER_NETBSD || SANITIZER_OPENBSD || SANITIZER_SOLARIS)
 
 #if __LP64__ || defined(_WIN64)
 #  define SANITIZER_WORDSIZE 64
@@ -333,7 +339,7 @@
 #endif
 
 #if SANITIZER_FREEBSD || SANITIZER_MAC || SANITIZER_NETBSD || \
-  SANITIZER_SOLARIS
+  SANITIZER_OPENBSD || SANITIZER_SOLARIS
 # define SANITIZER_MADVISE_DONTNEED MADV_FREE
 #else
 # define SANITIZER_MADVISE_DONTNEED MADV_DONTNEED
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
index 80a6b5990f2..37f178a6f57 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform_interceptors.h
@@ -36,6 +36,7 @@
 #if SI_POSIX
 # include "sanitizer_platform_limits_freebsd.h"
 # include "sanitizer_platform_limits_netbsd.h"
+# include "sanitizer_platform_limits_openbsd.h"
 # include "sanitizer_platform_limits_posix.h"
 # include "sanitizer_platform_limits_solaris.h"
 #endif
@@ -64,6 +65,12 @@
 # define SI_NETBSD 0
 #endif
 
+#if SANITIZER_OPENBSD
+#define SI_OPENBSD 1
+#else
+#define SI_OPENBSD 0
+#endif
+
 #if SANITIZER_LINUX
 # define SI_LINUX 1
 #else
@@ -157,7 +164,7 @@
 #define SANITIZER_INTERCEPT_MEMCMP SI_NOT_FUCHSIA
 #define SANITIZER_INTERCEPT_BCMP \
   SANITIZER_INTERCEPT_MEMCMP &&  \
-      ((SI_POSIX && _GNU_SOURCE) || SI_NETBSD || SI_FREEBSD)
+      ((SI_POSIX && _GNU_SOURCE) || SI_NETBSD || SI_OPENBSD || SI_FREEBSD)
 #define SANITIZER_INTERCEPT_STRNDUP SI_POSIX
 #define SANITIZER_INTERCEPT___STRNDUP SI_LINUX_NOT_FREEBSD
 #if defined(__ENVIRONMENT_MAC_OS_X_VERSION_MIN_REQUIRED__) && \
@@ -171,7 +178,7 @@
 #define SANITIZER_INTERCEPT_MEMMEM (SI_POSIX && !SI_MAC_DEPLOYMENT_BELOW_10_7)
 #define SANITIZER_INTERCEPT_MEMCHR SI_NOT_FUCHSIA
 #define SANITIZER_INTERCEPT_MEMRCHR \
-  (SI_FREEBSD || SI_LINUX || SI_NETBSD)
+  (SI_FREEBSD || SI_LINUX || SI_NETBSD || SI_OPENBSD)
 
 #define SANITIZER_INTERCEPT_READ SI_POSIX
 #define SANITIZER_INTERCEPT_PREAD SI_POSIX
@@ -191,7 +198,7 @@
 #define SANITIZER_INTERCEPT_WRITEV SI_POSIX
 
 #define SANITIZER_INTERCEPT_PREADV \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID)
 #define SANITIZER_INTERCEPT_PWRITEV SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_PREADV64 SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_PWRITEV64 SI_LINUX_NOT_ANDROID
@@ -218,22 +225,22 @@
 
 #define SANITIZER_INTERCEPT_GETPWNAM_AND_FRIENDS SI_POSIX
 #define SANITIZER_INTERCEPT_GETPWNAM_R_AND_FRIENDS                            \
-  (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_GETPWENT                                          \
-  (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_FGETGRENT_R                                       \
-  (SI_FREEBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_FGETPWENT SI_LINUX_NOT_ANDROID || SI_SOLARIS
 #define SANITIZER_INTERCEPT_GETPWENT_R \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_FGETPWENT_R \
-  (SI_FREEBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_SETPWENT \
   (SI_MAC || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_CLOCK_GETTIME \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_CLOCK_GETCPUCLOCKID SI_LINUX
 #define SANITIZER_INTERCEPT_GETITIMER SI_POSIX
 #define SANITIZER_INTERCEPT_TIME SI_POSIX
@@ -241,7 +248,7 @@
 #define SANITIZER_INTERCEPT_GLOB64 SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_WAIT SI_POSIX
 #define SANITIZER_INTERCEPT_INET SI_POSIX
-#define SANITIZER_INTERCEPT_PTHREAD_GETSCHEDPARAM SI_POSIX
+#define SANITIZER_INTERCEPT_PTHREAD_GETSCHEDPARAM (SI_POSIX && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_GETADDRINFO SI_POSIX
 #define SANITIZER_INTERCEPT_GETNAMEINFO SI_POSIX
 #define SANITIZER_INTERCEPT_GETSOCKNAME SI_POSIX
@@ -258,7 +265,7 @@
 #define SANITIZER_INTERCEPT_GETSOCKOPT SI_POSIX
 #define SANITIZER_INTERCEPT_ACCEPT SI_POSIX
 #define SANITIZER_INTERCEPT_ACCEPT4 \
-  (SI_LINUX_NOT_ANDROID || SI_NETBSD)
+  (SI_LINUX_NOT_ANDROID || SI_NETBSD || SI_OPENBSD)
 #define SANITIZER_INTERCEPT_PACCEPT SI_NETBSD
 #define SANITIZER_INTERCEPT_MODF SI_POSIX
 #define SANITIZER_INTERCEPT_RECVMSG SI_POSIX
@@ -293,20 +300,20 @@
 #define SANITIZER_INTERCEPT_WCSXFRM SI_POSIX
 #define SANITIZER_INTERCEPT___WCSXFRM_L SI_LINUX
 #define SANITIZER_INTERCEPT_WCSNRTOMBS                                        \
-  (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_WCRTOMB                                           \
-  (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_WCTOMB                                           \
-  (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_TCGETATTR SI_LINUX_NOT_ANDROID || SI_SOLARIS
 #define SANITIZER_INTERCEPT_REALPATH SI_POSIX
 #define SANITIZER_INTERCEPT_CANONICALIZE_FILE_NAME \
   (SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_CONFSTR                                           \
-  (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_SCHED_GETAFFINITY SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_SCHED_GETPARAM SI_LINUX_NOT_ANDROID || SI_SOLARIS
@@ -314,7 +321,7 @@
 #define SANITIZER_INTERCEPT_STRERROR_R SI_POSIX
 #define SANITIZER_INTERCEPT_XPG_STRERROR_R SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_SCANDIR \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_SCANDIR64 SI_LINUX_NOT_ANDROID || SI_SOLARIS32
 #define SANITIZER_INTERCEPT_GETGROUPS SI_POSIX
 #define SANITIZER_INTERCEPT_POLL SI_POSIX
@@ -332,7 +339,7 @@
 #define SANITIZER_INTERCEPT_SIGPROCMASK SI_POSIX
 #define SANITIZER_INTERCEPT_PTHREAD_SIGMASK SI_POSIX
 #define SANITIZER_INTERCEPT_BACKTRACE \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_GETMNTENT SI_LINUX
 #define SANITIZER_INTERCEPT_GETMNTENT_R SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_STATFS \
@@ -340,25 +347,25 @@
 #define SANITIZER_INTERCEPT_STATFS64 \
   (((SI_MAC && !TARGET_CPU_ARM64) && !SI_IOS) || SI_LINUX_NOT_ANDROID)
 #define SANITIZER_INTERCEPT_STATVFS \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID)
 #define SANITIZER_INTERCEPT_STATVFS64 SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_INITGROUPS SI_POSIX
-#define SANITIZER_INTERCEPT_ETHER_NTOA_ATON SI_POSIX
+#define SANITIZER_INTERCEPT_ETHER_NTOA_ATON (SI_POSIX && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_ETHER_HOST \
   (SI_FREEBSD || SI_MAC || SI_LINUX_NOT_ANDROID)
 #define SANITIZER_INTERCEPT_ETHER_R (SI_FREEBSD || SI_LINUX_NOT_ANDROID)
 #define SANITIZER_INTERCEPT_SHMCTL                                       \
   (((SI_FREEBSD || SI_LINUX_NOT_ANDROID) && SANITIZER_WORDSIZE == 64) || \
-   SI_NETBSD || SI_SOLARIS)  // NOLINT
+   SI_NETBSD || SI_OPENBSD || SI_SOLARIS)  // NOLINT
 #define SANITIZER_INTERCEPT_RANDOM_R SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_PTHREAD_ATTR_GET SI_POSIX
 #define SANITIZER_INTERCEPT_PTHREAD_ATTR_GETINHERITSCHED \
   (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PTHREAD_ATTR_GETAFFINITY_NP SI_LINUX_NOT_ANDROID
-#define SANITIZER_INTERCEPT_PTHREAD_ATTR_GET_SCHED SI_POSIX
+#define SANITIZER_INTERCEPT_PTHREAD_ATTR_GET_SCHED (SI_POSIX && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_PTHREAD_MUTEXATTR_GETPSHARED \
-  (SI_POSIX && !SI_NETBSD)
-#define SANITIZER_INTERCEPT_PTHREAD_MUTEXATTR_GETTYPE SI_POSIX
+  (SI_POSIX && !SI_NETBSD && !SI_OPENBSD)
+#define SANITIZER_INTERCEPT_PTHREAD_MUTEXATTR_GETTYPE (SI_POSIX && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_PTHREAD_MUTEXATTR_GETPROTOCOL \
   (SI_MAC || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PTHREAD_MUTEXATTR_GETPRIOCEILING \
@@ -367,14 +374,14 @@
   (SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PTHREAD_MUTEXATTR_GETROBUST_NP SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_PTHREAD_RWLOCKATTR_GETPSHARED \
-  (SI_POSIX && !SI_NETBSD)
+  (SI_POSIX && !SI_NETBSD && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_PTHREAD_RWLOCKATTR_GETKIND_NP SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_PTHREAD_CONDATTR_GETPSHARED \
-  (SI_POSIX && !SI_NETBSD)
+  (SI_POSIX && !SI_NETBSD && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_PTHREAD_CONDATTR_GETCLOCK \
   (SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PTHREAD_BARRIERATTR_GETPSHARED \
-  (SI_LINUX_NOT_ANDROID && !SI_NETBSD)
+  (SI_LINUX_NOT_ANDROID && !SI_NETBSD && !SI_OPENBSD)
 #define SANITIZER_INTERCEPT_THR_EXIT SI_FREEBSD
 #define SANITIZER_INTERCEPT_TMPNAM SI_POSIX
 #define SANITIZER_INTERCEPT_TMPNAM_R SI_LINUX_NOT_ANDROID || SI_SOLARIS
@@ -392,38 +399,38 @@
 #define SANITIZER_INTERCEPT_LGAMMAL_R SI_LINUX_NOT_ANDROID || SI_SOLARIS
 #define SANITIZER_INTERCEPT_DRAND48_R SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_RAND_R                                            \
-  (SI_FREEBSD || SI_NETBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_LINUX_NOT_ANDROID || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_ICONV \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_TIMES SI_POSIX
 
 // FIXME: getline seems to be available on OSX 10.7
 #define SANITIZER_INTERCEPT_GETLINE \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 
 #define SANITIZER_INTERCEPT__EXIT \
-  (SI_LINUX || SI_FREEBSD || SI_NETBSD || SI_MAC || SI_SOLARIS)
+  (SI_LINUX || SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_MAC || SI_SOLARIS)
 
 #define SANITIZER_INTERCEPT_PTHREAD_MUTEX SI_POSIX
 #define SANITIZER_INTERCEPT___PTHREAD_MUTEX SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT___LIBC_MUTEX SI_NETBSD
 #define SANITIZER_INTERCEPT_PTHREAD_SETNAME_NP \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PTHREAD_GETNAME_NP \
   (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 
 #define SANITIZER_INTERCEPT_TLS_GET_ADDR \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_SOLARIS)
 
 #define SANITIZER_INTERCEPT_LISTXATTR SI_LINUX
 #define SANITIZER_INTERCEPT_GETXATTR SI_LINUX
 #define SANITIZER_INTERCEPT_GETRESID SI_LINUX
 #define SANITIZER_INTERCEPT_GETIFADDRS                                        \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_MAC || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_MAC || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_IF_INDEXTONAME                                    \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_MAC || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_MAC || \
   SI_SOLARIS)
 #define SANITIZER_INTERCEPT_CAPGET SI_LINUX_NOT_ANDROID
 #if SI_LINUX && defined(__arm__)
@@ -434,28 +441,28 @@
 #define SANITIZER_INTERCEPT___BZERO SI_MAC || SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_BZERO SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_FTIME \
-  (!SI_FREEBSD && !SI_NETBSD && SI_POSIX)
+  (!SI_FREEBSD && !SI_NETBSD && !SI_OPENBSD && SI_POSIX)
 #define SANITIZER_INTERCEPT_XDR SI_LINUX_NOT_ANDROID || SI_SOLARIS
 #define SANITIZER_INTERCEPT_XDRREC SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_TSEARCH \
-  (SI_LINUX_NOT_ANDROID || SI_MAC || SI_NETBSD || SI_SOLARIS)
+  (SI_LINUX_NOT_ANDROID || SI_MAC || SI_NETBSD || SI_OPENBSD || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_LIBIO_INTERNALS SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_FOPEN SI_POSIX
 #define SANITIZER_INTERCEPT_FOPEN64 SI_LINUX_NOT_ANDROID || SI_SOLARIS32
 #define SANITIZER_INTERCEPT_OPEN_MEMSTREAM \
-  (SI_LINUX_NOT_ANDROID || SI_NETBSD || SI_SOLARIS)
+  (SI_LINUX_NOT_ANDROID || SI_NETBSD || SI_OPENBSD || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_OBSTACK SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_FFLUSH SI_POSIX
 #define SANITIZER_INTERCEPT_FCLOSE SI_POSIX
 
 #ifndef SANITIZER_INTERCEPT_DLOPEN_DLCLOSE
 #define SANITIZER_INTERCEPT_DLOPEN_DLCLOSE                                    \
-  (SI_FREEBSD || SI_NETBSD || SI_LINUX_NOT_ANDROID || SI_MAC || \
+  (SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_LINUX_NOT_ANDROID || SI_MAC || \
   SI_SOLARIS)
 #endif
 
 #define SANITIZER_INTERCEPT_GETPASS \
-  (SI_LINUX_NOT_ANDROID || SI_MAC || SI_NETBSD)
+  (SI_LINUX_NOT_ANDROID || SI_MAC || SI_NETBSD || SI_OPENBSD)
 #define SANITIZER_INTERCEPT_TIMERFD SI_LINUX_NOT_ANDROID
 
 #define SANITIZER_INTERCEPT_MLOCKX SI_POSIX
@@ -464,10 +471,10 @@
   (SI_LINUX || SI_FREEBSD || SI_NETBSD || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PTHREAD_SETCANCEL SI_POSIX
 #define SANITIZER_INTERCEPT_MINCORE \
-  (SI_LINUX || SI_NETBSD || SI_SOLARIS)
+  (SI_LINUX || SI_NETBSD || SI_OPENBSD || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_PROCESS_VM_READV SI_LINUX
 #define SANITIZER_INTERCEPT_CTERMID \
-  (SI_LINUX || SI_MAC || SI_FREEBSD || SI_NETBSD || SI_SOLARIS)
+  (SI_LINUX || SI_MAC || SI_FREEBSD || SI_NETBSD || SI_OPENBSD || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_CTERMID_R (SI_MAC || SI_FREEBSD || SI_SOLARIS)
 
 #define SANITIZER_INTERCEPTOR_HOOKS \
@@ -477,7 +484,7 @@
 #define SANITIZER_INTERCEPT_EVENTFD_READ_WRITE SI_LINUX
 
 #define SANITIZER_INTERCEPT_STAT \
-  (SI_FREEBSD || SI_MAC || SI_ANDROID || SI_NETBSD || SI_SOLARIS)
+  (SI_FREEBSD || SI_MAC || SI_ANDROID || SI_NETBSD || SI_OPENBSD || SI_SOLARIS)
 #define SANITIZER_INTERCEPT_LSTAT (SI_NETBSD || SI_FREEBSD)
 #define SANITIZER_INTERCEPT___XSTAT (!SANITIZER_INTERCEPT_STAT && SI_POSIX)
 #define SANITIZER_INTERCEPT___XSTAT64 SI_LINUX_NOT_ANDROID
@@ -490,41 +497,41 @@
   (SI_LINUX_NOT_ANDROID || SI_MAC || SI_FREEBSD || SI_NETBSD)
 
 #define SANITIZER_INTERCEPT_GETLOADAVG \
-  (SI_LINUX_NOT_ANDROID || SI_MAC || SI_FREEBSD || SI_NETBSD)
+  (SI_LINUX_NOT_ANDROID || SI_MAC || SI_FREEBSD || SI_NETBSD || SI_OPENBSD)
 
 #define SANITIZER_INTERCEPT_MMAP SI_POSIX
 #define SANITIZER_INTERCEPT_MMAP64 SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_MALLOPT_AND_MALLINFO                            \
-  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && SI_NOT_FUCHSIA && \
+  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && !SI_OPENBSD && SI_NOT_FUCHSIA && \
    SI_NOT_RTEMS && !SI_SOLARIS)  // NOLINT
 #define SANITIZER_INTERCEPT_MEMALIGN \
-  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && SI_NOT_RTEMS)
+  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && !SI_OPENBSD && SI_NOT_RTEMS)
 #define SANITIZER_INTERCEPT_PVALLOC                                         \
-  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && SI_NOT_FUCHSIA && \
+  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && !SI_OPENBSD && SI_NOT_FUCHSIA && \
    SI_NOT_RTEMS && !SI_SOLARIS)  // NOLINT
 #define SANITIZER_INTERCEPT_CFREE                                           \
-  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && SI_NOT_FUCHSIA && \
+  (!SI_FREEBSD && !SI_MAC && !SI_NETBSD && !SI_OPENBSD && SI_NOT_FUCHSIA && \
    SI_NOT_RTEMS && !SI_SOLARIS)  // NOLINT
 #define SANITIZER_INTERCEPT_REALLOCARRAY SI_POSIX
 #define SANITIZER_INTERCEPT_ALIGNED_ALLOC (!SI_MAC && SI_NOT_RTEMS)
 #define SANITIZER_INTERCEPT_MALLOC_USABLE_SIZE \
-  (!SI_MAC && !SI_NETBSD)
+  (!SI_MAC && !SI_OPENBSD && !SI_NETBSD)
 #define SANITIZER_INTERCEPT_MCHECK_MPROBE SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_WCSCAT SI_POSIX
 #define SANITIZER_INTERCEPT_WCSDUP SI_POSIX
 #define SANITIZER_INTERCEPT_SIGNAL_AND_SIGACTION (!SI_WINDOWS && SI_NOT_FUCHSIA)
 #define SANITIZER_INTERCEPT_BSD_SIGNAL SI_ANDROID
 
-#define SANITIZER_INTERCEPT_ACCT (SI_NETBSD || SI_FREEBSD)
+#define SANITIZER_INTERCEPT_ACCT (SI_NETBSD || SI_OPENBSD || SI_FREEBSD)
 #define SANITIZER_INTERCEPT_USER_FROM_UID SI_NETBSD
 #define SANITIZER_INTERCEPT_UID_FROM_USER SI_NETBSD
 #define SANITIZER_INTERCEPT_GROUP_FROM_GID SI_NETBSD
 #define SANITIZER_INTERCEPT_GID_FROM_GROUP SI_NETBSD
-#define SANITIZER_INTERCEPT_ACCESS (SI_NETBSD || SI_FREEBSD)
-#define SANITIZER_INTERCEPT_FACCESSAT (SI_NETBSD || SI_FREEBSD)
-#define SANITIZER_INTERCEPT_GETGROUPLIST SI_NETBSD
+#define SANITIZER_INTERCEPT_ACCESS (SI_NETBSD || SI_OPENBSD || SI_FREEBSD)
+#define SANITIZER_INTERCEPT_FACCESSAT (SI_NETBSD || SI_OPENBSD || SI_FREEBSD)
+#define SANITIZER_INTERCEPT_GETGROUPLIST (SI_NETBSD || SI_OPENBSD)
 #define SANITIZER_INTERCEPT_STRLCPY                                            \
-  (SI_NETBSD || SI_FREEBSD || SI_MAC || SI_ANDROID)
+  (SI_NETBSD || SI_FREEBSD || SI_OPENBSD || SI_MAC || SI_ANDROID)
 
 #define SANITIZER_INTERCEPT_NAME_TO_HANDLE_AT SI_LINUX_NOT_ANDROID
 #define SANITIZER_INTERCEPT_OPEN_BY_HANDLE_AT SI_LINUX_NOT_ANDROID
@@ -539,7 +546,7 @@
 #define SANITIZER_INTERCEPT_READLINKAT \
   (SI_POSIX && !SI_MAC_DEPLOYMENT_BELOW_10_10)
 
-#define SANITIZER_INTERCEPT_DEVNAME (SI_NETBSD || SI_FREEBSD)
+#define SANITIZER_INTERCEPT_DEVNAME (SI_NETBSD || SI_OPENBSD || SI_FREEBSD)
 #define SANITIZER_INTERCEPT_DEVNAME_R (SI_NETBSD || SI_FREEBSD)
 #define SANITIZER_INTERCEPT_FGETLN (SI_NETBSD || SI_FREEBSD)
 #define SANITIZER_INTERCEPT_STRMODE (SI_NETBSD || SI_FREEBSD)
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_openbsd.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_openbsd.cpp
new file mode 100644
index 00000000000..1420ecbfa56
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_openbsd.cpp
@@ -0,0 +1,279 @@
+//===-- sanitizer_platform_limits_openbsd.cpp -----------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of Sanitizer common code.
+//
+// Sizes and layouts of platform-specific NetBSD data structures.
+//===----------------------------------------------------------------------===//
+
+#include "sanitizer_platform.h"
+
+#if SANITIZER_OPENBSD
+#include <arpa/inet.h>
+#include <dirent.h>
+#include <glob.h>
+#include <grp.h>
+#include <ifaddrs.h>
+#include <limits.h>
+#include <link_elf.h>
+#include <sys/socket.h>
+#include <net/if.h>
+#include <net/ppp_defs.h>
+#include <net/route.h>
+#include <netdb.h>
+#include <netinet/in.h>
+#include <netinet/ip_mroute.h>
+#include <poll.h>
+#include <pthread.h>
+#include <pwd.h>
+#include <semaphore.h>
+#include <signal.h>
+#include <soundcard.h>
+#include <stddef.h>
+#include <stdint.h>
+#include <sys/filio.h>
+#include <sys/ipc.h>
+#include <sys/mman.h>
+#include <sys/mount.h>
+#include <sys/msg.h>
+#include <sys/mtio.h>
+#include <sys/ptrace.h>
+#include <sys/resource.h>
+#include <sys/shm.h>
+#include <sys/signal.h>
+#include <sys/sockio.h>
+#include <sys/stat.h>
+#include <sys/statvfs.h>
+#include <sys/time.h>
+#include <sys/times.h>
+#include <sys/types.h>
+#include <sys/utsname.h>
+#include <term.h>
+#include <time.h>
+#include <utime.h>
+#include <utmp.h>
+#include <wchar.h>
+
+// Include these after system headers to avoid name clashes and ambiguities.
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_platform_limits_openbsd.h"
+
+namespace __sanitizer {
+unsigned struct_utsname_sz = sizeof(struct utsname);
+unsigned struct_stat_sz = sizeof(struct stat);
+unsigned struct_rusage_sz = sizeof(struct rusage);
+unsigned struct_tm_sz = sizeof(struct tm);
+unsigned struct_passwd_sz = sizeof(struct passwd);
+unsigned struct_group_sz = sizeof(struct group);
+unsigned siginfo_t_sz = sizeof(siginfo_t);
+unsigned struct_sigaction_sz = sizeof(struct sigaction);
+unsigned struct_stack_t_sz = sizeof(stack_t);
+unsigned struct_itimerval_sz = sizeof(struct itimerval);
+unsigned pthread_t_sz = sizeof(pthread_t);
+unsigned pthread_mutex_t_sz = sizeof(pthread_mutex_t);
+unsigned pthread_cond_t_sz = sizeof(pthread_cond_t);
+unsigned pid_t_sz = sizeof(pid_t);
+unsigned timeval_sz = sizeof(timeval);
+unsigned uid_t_sz = sizeof(uid_t);
+unsigned gid_t_sz = sizeof(gid_t);
+unsigned mbstate_t_sz = sizeof(mbstate_t);
+unsigned sigset_t_sz = sizeof(sigset_t);
+unsigned struct_timezone_sz = sizeof(struct timezone);
+unsigned struct_tms_sz = sizeof(struct tms);
+unsigned struct_sched_param_sz = sizeof(struct sched_param);
+unsigned struct_sockaddr_sz = sizeof(struct sockaddr);
+unsigned struct_rlimit_sz = sizeof(struct rlimit);
+unsigned struct_timespec_sz = sizeof(struct timespec);
+unsigned struct_utimbuf_sz = sizeof(struct utimbuf);
+unsigned struct_itimerspec_sz = sizeof(struct itimerspec);
+unsigned struct_msqid_ds_sz = sizeof(struct msqid_ds);
+unsigned struct_statvfs_sz = sizeof(struct statvfs);
+
+const uptr sig_ign = (uptr)SIG_IGN;
+const uptr sig_dfl = (uptr)SIG_DFL;
+const uptr sig_err = (uptr)SIG_ERR;
+const uptr sa_siginfo = (uptr)SA_SIGINFO;
+
+int shmctl_ipc_stat = (int)IPC_STAT;
+
+unsigned struct_utmp_sz = sizeof(struct utmp);
+
+int map_fixed = MAP_FIXED;
+
+int af_inet = (int)AF_INET;
+int af_inet6 = (int)AF_INET6;
+
+uptr __sanitizer_in_addr_sz(int af) {
+  if (af == AF_INET)
+    return sizeof(struct in_addr);
+  else if (af == AF_INET6)
+    return sizeof(struct in6_addr);
+  else
+    return 0;
+}
+
+unsigned struct_ElfW_Phdr_sz = sizeof(Elf_Phdr);
+
+int glob_nomatch = GLOB_NOMATCH;
+int glob_altdirfunc = GLOB_ALTDIRFUNC;
+
+unsigned path_max = PATH_MAX;
+
+const int si_SEGV_MAPERR = SEGV_MAPERR;
+const int si_SEGV_ACCERR = SEGV_ACCERR;
+}  // namespace __sanitizer
+
+using namespace __sanitizer;
+
+COMPILER_CHECK(sizeof(__sanitizer_pthread_attr_t) >= sizeof(pthread_attr_t));
+
+COMPILER_CHECK(sizeof(socklen_t) == sizeof(unsigned));
+CHECK_TYPE_SIZE(pthread_key_t);
+
+CHECK_TYPE_SIZE(dl_phdr_info);
+CHECK_SIZE_AND_OFFSET(dl_phdr_info, dlpi_addr);
+CHECK_SIZE_AND_OFFSET(dl_phdr_info, dlpi_name);
+CHECK_SIZE_AND_OFFSET(dl_phdr_info, dlpi_phdr);
+CHECK_SIZE_AND_OFFSET(dl_phdr_info, dlpi_phnum);
+
+CHECK_TYPE_SIZE(glob_t);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_pathc);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_pathv);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_offs);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_flags);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_closedir);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_readdir);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_opendir);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_lstat);
+CHECK_SIZE_AND_OFFSET(glob_t, gl_stat);
+
+CHECK_TYPE_SIZE(addrinfo);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_flags);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_family);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_socktype);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_protocol);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_addrlen);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_addr);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_canonname);
+CHECK_SIZE_AND_OFFSET(addrinfo, ai_next);
+
+CHECK_TYPE_SIZE(hostent);
+CHECK_SIZE_AND_OFFSET(hostent, h_name);
+CHECK_SIZE_AND_OFFSET(hostent, h_aliases);
+CHECK_SIZE_AND_OFFSET(hostent, h_addrtype);
+CHECK_SIZE_AND_OFFSET(hostent, h_length);
+CHECK_SIZE_AND_OFFSET(hostent, h_addr_list);
+
+CHECK_TYPE_SIZE(iovec);
+CHECK_SIZE_AND_OFFSET(iovec, iov_base);
+CHECK_SIZE_AND_OFFSET(iovec, iov_len);
+
+CHECK_TYPE_SIZE(msghdr);
+CHECK_SIZE_AND_OFFSET(msghdr, msg_name);
+CHECK_SIZE_AND_OFFSET(msghdr, msg_namelen);
+CHECK_SIZE_AND_OFFSET(msghdr, msg_iov);
+CHECK_SIZE_AND_OFFSET(msghdr, msg_iovlen);
+CHECK_SIZE_AND_OFFSET(msghdr, msg_control);
+CHECK_SIZE_AND_OFFSET(msghdr, msg_controllen);
+CHECK_SIZE_AND_OFFSET(msghdr, msg_flags);
+
+CHECK_TYPE_SIZE(cmsghdr);
+CHECK_SIZE_AND_OFFSET(cmsghdr, cmsg_len);
+CHECK_SIZE_AND_OFFSET(cmsghdr, cmsg_level);
+CHECK_SIZE_AND_OFFSET(cmsghdr, cmsg_type);
+
+COMPILER_CHECK(sizeof(__sanitizer_dirent) <= sizeof(dirent));
+CHECK_SIZE_AND_OFFSET(dirent, d_fileno);
+CHECK_SIZE_AND_OFFSET(dirent, d_off);
+CHECK_SIZE_AND_OFFSET(dirent, d_reclen);
+
+CHECK_TYPE_SIZE(ifconf);
+CHECK_SIZE_AND_OFFSET(ifconf, ifc_len);
+CHECK_SIZE_AND_OFFSET(ifconf, ifc_ifcu);
+
+CHECK_TYPE_SIZE(pollfd);
+CHECK_SIZE_AND_OFFSET(pollfd, fd);
+CHECK_SIZE_AND_OFFSET(pollfd, events);
+CHECK_SIZE_AND_OFFSET(pollfd, revents);
+
+CHECK_TYPE_SIZE(nfds_t);
+
+CHECK_TYPE_SIZE(sigset_t);
+
+COMPILER_CHECK(sizeof(__sanitizer_sigaction) == sizeof(struct sigaction));
+// Can't write checks for sa_handler and sa_sigaction due to them being
+// preprocessor macros.
+CHECK_STRUCT_SIZE_AND_OFFSET(sigaction, sa_mask);
+
+CHECK_TYPE_SIZE(tm);
+CHECK_SIZE_AND_OFFSET(tm, tm_sec);
+CHECK_SIZE_AND_OFFSET(tm, tm_min);
+CHECK_SIZE_AND_OFFSET(tm, tm_hour);
+CHECK_SIZE_AND_OFFSET(tm, tm_mday);
+CHECK_SIZE_AND_OFFSET(tm, tm_mon);
+CHECK_SIZE_AND_OFFSET(tm, tm_year);
+CHECK_SIZE_AND_OFFSET(tm, tm_wday);
+CHECK_SIZE_AND_OFFSET(tm, tm_yday);
+CHECK_SIZE_AND_OFFSET(tm, tm_isdst);
+CHECK_SIZE_AND_OFFSET(tm, tm_gmtoff);
+CHECK_SIZE_AND_OFFSET(tm, tm_zone);
+
+CHECK_TYPE_SIZE(ipc_perm);
+CHECK_SIZE_AND_OFFSET(ipc_perm, cuid);
+CHECK_SIZE_AND_OFFSET(ipc_perm, cgid);
+CHECK_SIZE_AND_OFFSET(ipc_perm, uid);
+CHECK_SIZE_AND_OFFSET(ipc_perm, gid);
+CHECK_SIZE_AND_OFFSET(ipc_perm, mode);
+CHECK_SIZE_AND_OFFSET(ipc_perm, seq);
+CHECK_SIZE_AND_OFFSET(ipc_perm, key);
+
+CHECK_TYPE_SIZE(shmid_ds);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_perm);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_segsz);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_atime);
+CHECK_SIZE_AND_OFFSET(shmid_ds, __shm_atimensec);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_dtime);
+CHECK_SIZE_AND_OFFSET(shmid_ds, __shm_dtimensec);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_ctime);
+CHECK_SIZE_AND_OFFSET(shmid_ds, __shm_ctimensec);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_cpid);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_lpid);
+CHECK_SIZE_AND_OFFSET(shmid_ds, shm_nattch);
+
+CHECK_TYPE_SIZE(clock_t);
+
+CHECK_TYPE_SIZE(ifaddrs);
+CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_next);
+CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_name);
+CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_addr);
+CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_netmask);
+// Compare against the union, because we can't reach into the union in a
+// compliant way.
+#ifdef ifa_dstaddr
+#undef ifa_dstaddr
+#endif
+CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_dstaddr);
+CHECK_SIZE_AND_OFFSET(ifaddrs, ifa_data);
+
+CHECK_TYPE_SIZE(passwd);
+CHECK_SIZE_AND_OFFSET(passwd, pw_name);
+CHECK_SIZE_AND_OFFSET(passwd, pw_passwd);
+CHECK_SIZE_AND_OFFSET(passwd, pw_uid);
+CHECK_SIZE_AND_OFFSET(passwd, pw_gid);
+CHECK_SIZE_AND_OFFSET(passwd, pw_dir);
+CHECK_SIZE_AND_OFFSET(passwd, pw_shell);
+
+CHECK_SIZE_AND_OFFSET(passwd, pw_gecos);
+
+CHECK_TYPE_SIZE(group);
+CHECK_SIZE_AND_OFFSET(group, gr_name);
+CHECK_SIZE_AND_OFFSET(group, gr_passwd);
+CHECK_SIZE_AND_OFFSET(group, gr_gid);
+CHECK_SIZE_AND_OFFSET(group, gr_mem);
+
+#endif  // SANITIZER_OPENBSD
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_openbsd.h b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_openbsd.h
new file mode 100644
index 00000000000..8a194872360
--- /dev/null
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_platform_limits_openbsd.h
@@ -0,0 +1,382 @@
+//===-- sanitizer_platform_limits_openbsd.h -------------------------------===//
+//
+// 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
+//
+//===----------------------------------------------------------------------===//
+//
+// This file is a part of Sanitizer common code.
+//
+// Sizes and layouts of platform-specific OpenBSD data structures.
+//===----------------------------------------------------------------------===//
+
+#ifndef SANITIZER_PLATFORM_LIMITS_OPENBSD_H
+#define SANITIZER_PLATFORM_LIMITS_OPENBSD_H
+
+#if SANITIZER_OPENBSD
+
+#include "sanitizer_internal_defs.h"
+#include "sanitizer_platform.h"
+
+#define _GET_LINK_MAP_BY_DLOPEN_HANDLE(handle, shift) \
+  ((link_map *)((handle) == nullptr ? nullptr : ((char *)(handle) + (shift))))
+
+#if defined(__x86_64__)
+#define GET_LINK_MAP_BY_DLOPEN_HANDLE(handle) \
+  _GET_LINK_MAP_BY_DLOPEN_HANDLE(handle, 312)
+#elif defined(__i386__)
+#define GET_LINK_MAP_BY_DLOPEN_HANDLE(handle) \
+  _GET_LINK_MAP_BY_DLOPEN_HANDLE(handle, 164)
+#endif
+
+#define RLIMIT_AS RLIMIT_DATA
+
+namespace __sanitizer {
+extern unsigned struct_utsname_sz;
+extern unsigned struct_stat_sz;
+extern unsigned struct_rusage_sz;
+extern unsigned siginfo_t_sz;
+extern unsigned struct_itimerval_sz;
+extern unsigned pthread_t_sz;
+extern unsigned pthread_mutex_t_sz;
+extern unsigned pthread_cond_t_sz;
+extern unsigned pid_t_sz;
+extern unsigned timeval_sz;
+extern unsigned uid_t_sz;
+extern unsigned gid_t_sz;
+extern unsigned mbstate_t_sz;
+extern unsigned struct_timezone_sz;
+extern unsigned struct_tms_sz;
+extern unsigned struct_itimerspec_sz;
+extern unsigned struct_sigevent_sz;
+extern unsigned struct_stack_t_sz;
+extern unsigned struct_statfs_sz;
+extern unsigned struct_sockaddr_sz;
+
+extern unsigned struct_rlimit_sz;
+extern unsigned struct_utimbuf_sz;
+extern unsigned struct_timespec_sz;
+
+struct __sanitizer_iocb {
+  u64 aio_offset;
+  uptr aio_buf;
+  long aio_nbytes;
+  u32 aio_fildes;
+  u32 aio_lio_opcode;
+  long aio_reqprio;
+#if SANITIZER_WORDSIZE == 64
+  u8 aio_sigevent[32];
+#else
+  u8 aio_sigevent[20];
+#endif
+  u32 _state;
+  u32 _errno;
+  long _retval;
+};
+
+struct __sanitizer___sysctl_args {
+  int *name;
+  int nlen;
+  void *oldval;
+  uptr *oldlenp;
+  void *newval;
+  uptr newlen;
+};
+
+struct __sanitizer_sem_t {
+  uptr data[5];
+};
+
+struct __sanitizer_ipc_perm {
+  u32 cuid;
+  u32 cgid;
+  u32 uid;
+  u32 gid;
+  u32 mode;
+  unsigned short seq;
+  long key;
+};
+
+struct __sanitizer_shmid_ds {
+  __sanitizer_ipc_perm shm_perm;
+  int shm_segsz;
+  u32 shm_lpid;
+  u32 shm_cpid;
+  short shm_nattch;
+  u64 shm_atime;
+  long __shm_atimensec;
+  u64 shm_dtime;
+  long __shm_dtimensec;
+  u64 shm_ctime;
+  long __shm_ctimensec;
+  void *_shm_internal;
+};
+
+extern unsigned struct_msqid_ds_sz;
+extern unsigned struct_mq_attr_sz;
+extern unsigned struct_timex_sz;
+extern unsigned struct_statvfs_sz;
+
+struct __sanitizer_iovec {
+  void *iov_base;
+  uptr iov_len;
+};
+
+struct __sanitizer_ifaddrs {
+  struct __sanitizer_ifaddrs *ifa_next;
+  char *ifa_name;
+  unsigned int ifa_flags;
+  struct __sanitizer_sockaddr *ifa_addr;     // (struct sockaddr *)
+  struct __sanitizer_sockaddr *ifa_netmask;  // (struct sockaddr *)
+  struct __sanitizer_sockaddr *ifa_dstaddr;  // (struct sockaddr *)
+  void *ifa_data;
+};
+
+typedef unsigned __sanitizer_pthread_key_t;
+
+typedef long long __sanitizer_time_t;
+typedef int __sanitizer_suseconds_t;
+
+struct __sanitizer_timeval {
+  __sanitizer_time_t tv_sec;
+  __sanitizer_suseconds_t tv_usec;
+};
+
+struct __sanitizer_itimerval {
+  struct __sanitizer_timeval it_interval;
+  struct __sanitizer_timeval it_value;
+};
+
+struct __sanitizer_passwd {
+  char *pw_name;
+  char *pw_passwd;
+  int pw_uid;
+  int pw_gid;
+  __sanitizer_time_t pw_change;
+  char *pw_class;
+  char *pw_gecos;
+  char *pw_dir;
+  char *pw_shell;
+  __sanitizer_time_t pw_expire;
+};
+
+struct __sanitizer_group {
+  char *gr_name;
+  char *gr_passwd;
+  int gr_gid;
+  char **gr_mem;
+};
+
+struct __sanitizer_ether_addr {
+  u8 octet[6];
+};
+
+struct __sanitizer_tm {
+  int tm_sec;
+  int tm_min;
+  int tm_hour;
+  int tm_mday;
+  int tm_mon;
+  int tm_year;
+  int tm_wday;
+  int tm_yday;
+  int tm_isdst;
+  long int tm_gmtoff;
+  const char *tm_zone;
+};
+
+struct __sanitizer_msghdr {
+  void *msg_name;
+  unsigned msg_namelen;
+  struct __sanitizer_iovec *msg_iov;
+  unsigned msg_iovlen;
+  void *msg_control;
+  unsigned msg_controllen;
+  int msg_flags;
+};
+struct __sanitizer_cmsghdr {
+  unsigned cmsg_len;
+  int cmsg_level;
+  int cmsg_type;
+};
+
+struct __sanitizer_dirent {
+  u64 d_fileno;
+  u64 d_off;
+  u16 d_reclen;
+};
+
+typedef u64 __sanitizer_clock_t;
+typedef u32 __sanitizer_clockid_t;
+
+typedef u32 __sanitizer___kernel_uid_t;
+typedef u32 __sanitizer___kernel_gid_t;
+typedef u64 __sanitizer___kernel_off_t;
+typedef struct {
+  u32 fds_bits[8];
+} __sanitizer___kernel_fd_set;
+
+typedef struct {
+  unsigned int pta_magic;
+  int pta_flags;
+  void *pta_private;
+} __sanitizer_pthread_attr_t;
+
+typedef unsigned int __sanitizer_sigset_t;
+
+struct __sanitizer_siginfo {
+  // The size is determined by looking at sizeof of real siginfo_t on linux.
+  u64 opaque[128 / sizeof(u64)];
+};
+
+using __sanitizer_sighandler_ptr = void (*)(int sig);
+using __sanitizer_sigactionhandler_ptr = void (*)(int sig,
+                                                  __sanitizer_siginfo *siginfo,
+                                                  void *uctx);
+
+struct __sanitizer_sigaction {
+  union {
+    __sanitizer_sighandler_ptr handler;
+    __sanitizer_sigactionhandler_ptr sigaction;
+  };
+  __sanitizer_sigset_t sa_mask;
+  int sa_flags;
+};
+
+typedef __sanitizer_sigset_t __sanitizer_kernel_sigset_t;
+
+struct __sanitizer_kernel_sigaction_t {
+  union {
+    void (*handler)(int signo);
+    void (*sigaction)(int signo, void *info, void *ctx);
+  };
+  unsigned long sa_flags;
+  void (*sa_restorer)(void);
+  __sanitizer_kernel_sigset_t sa_mask;
+};
+
+extern const uptr sig_ign;
+extern const uptr sig_dfl;
+extern const uptr sig_err;
+extern const uptr sa_siginfo;
+
+extern int af_inet;
+extern int af_inet6;
+uptr __sanitizer_in_addr_sz(int af);
+
+struct __sanitizer_dl_phdr_info {
+#if SANITIZER_WORDSIZE == 64
+  u64 dlpi_addr;
+#else
+  u32 dlpi_addr;
+#endif
+  const char *dlpi_name;
+  const void *dlpi_phdr;
+#if SANITIZER_WORDSIZE == 64
+  u32 dlpi_phnum;
+#else
+  u16 dlpi_phnum;
+#endif
+};
+
+extern unsigned struct_ElfW_Phdr_sz;
+
+struct __sanitizer_addrinfo {
+  int ai_flags;
+  int ai_family;
+  int ai_socktype;
+  int ai_protocol;
+  unsigned ai_addrlen;
+  struct __sanitizer_sockaddr *ai_addr;
+  char *ai_canonname;
+  struct __sanitizer_addrinfo *ai_next;
+};
+
+struct __sanitizer_hostent {
+  char *h_name;
+  char **h_aliases;
+  int h_addrtype;
+  int h_length;
+  char **h_addr_list;
+};
+
+struct __sanitizer_pollfd {
+  int fd;
+  short events;
+  short revents;
+};
+
+typedef unsigned __sanitizer_nfds_t;
+
+struct __sanitizer_glob_t {
+  int gl_pathc;
+  int gl_matchc;
+  int gl_offs;
+  int gl_flags;
+  char **gl_pathv;
+  void **gl_statv;
+  int (*gl_errfunc)(const char *, int);
+  void (*gl_closedir)(void *dirp);
+  struct dirent *(*gl_readdir)(void *dirp);
+  void *(*gl_opendir)(const char *);
+  int (*gl_lstat)(const char *, void * /* struct stat* */);
+  int (*gl_stat)(const char *, void * /* struct stat* */);
+};
+
+extern int glob_nomatch;
+extern int glob_altdirfunc;
+
+extern unsigned path_max;
+
+typedef char __sanitizer_FILE;
+#define SANITIZER_HAS_STRUCT_FILE 0
+
+extern int shmctl_ipc_stat;
+
+// This simplifies generic code
+#define struct_shminfo_sz -1
+#define struct_shm_info_sz -1
+#define shmctl_shm_stat -1
+#define shmctl_ipc_info -1
+#define shmctl_shm_info -1
+
+extern unsigned struct_utmp_sz;
+extern unsigned struct_utmpx_sz;
+
+extern int map_fixed;
+
+// ioctl arguments
+struct __sanitizer_ifconf {
+  int ifc_len;
+  union {
+    void *ifcu_req;
+  } ifc_ifcu;
+};
+
+extern const int si_SEGV_MAPERR;
+extern const int si_SEGV_ACCERR;
+}  // namespace __sanitizer
+
+#define CHECK_TYPE_SIZE(TYPE) \
+  COMPILER_CHECK(sizeof(__sanitizer_##TYPE) == sizeof(TYPE))
+
+#define CHECK_SIZE_AND_OFFSET(CLASS, MEMBER)                      \
+  COMPILER_CHECK(sizeof(((__sanitizer_##CLASS *)NULL)->MEMBER) == \
+                 sizeof(((CLASS *)NULL)->MEMBER));                \
+  COMPILER_CHECK(offsetof(__sanitizer_##CLASS, MEMBER) ==         \
+                 offsetof(CLASS, MEMBER))
+
+// For sigaction, which is a function and struct at the same time,
+// and thus requires explicit "struct" in sizeof() expression.
+#define CHECK_STRUCT_SIZE_AND_OFFSET(CLASS, MEMBER)                      \
+  COMPILER_CHECK(sizeof(((struct __sanitizer_##CLASS *)NULL)->MEMBER) == \
+                 sizeof(((struct CLASS *)NULL)->MEMBER));                \
+  COMPILER_CHECK(offsetof(struct __sanitizer_##CLASS, MEMBER) ==         \
+                 offsetof(struct CLASS, MEMBER))
+
+#define SIGACTION_SYMNAME __sigaction14
+
+#endif  // SANITIZER_OPENBSD
+
+#endif
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix.h b/compiler-rt/lib/sanitizer_common/sanitizer_posix.h
index e1a2b48e5cd..66bcaf4fd2e 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix.h
@@ -17,6 +17,7 @@
 #include "sanitizer_internal_defs.h"
 #include "sanitizer_platform_limits_freebsd.h"
 #include "sanitizer_platform_limits_netbsd.h"
+#include "sanitizer_platform_limits_openbsd.h"
 #include "sanitizer_platform_limits_posix.h"
 #include "sanitizer_platform_limits_solaris.h"
 
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
index d29438cf9db..37aaec362dd 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_posix_libcdep.cpp
@@ -18,6 +18,7 @@
 #include "sanitizer_common.h"
 #include "sanitizer_flags.h"
 #include "sanitizer_platform_limits_netbsd.h"
+#include "sanitizer_platform_limits_openbsd.h"
 #include "sanitizer_platform_limits_posix.h"
 #include "sanitizer_platform_limits_solaris.h"
 #include "sanitizer_posix.h"
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps.h b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps.h
index a56640db43e..665ed45fa93 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps.h
@@ -16,7 +16,7 @@
 #include "sanitizer_platform.h"
 
 #if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
-    SANITIZER_MAC || SANITIZER_SOLARIS ||  \
+    SANITIZER_OPENBSD || SANITIZER_MAC || SANITIZER_SOLARIS ||  \
     SANITIZER_FUCHSIA
 
 #include "sanitizer_common.h"
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_bsd.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_bsd.cpp
index 1f489b71ad9..02ff7c0e91a 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_bsd.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_bsd.cpp
@@ -7,11 +7,11 @@
 //===----------------------------------------------------------------------===//
 //
 // Information about the process mappings
-// (FreeBSD and NetBSD-specific parts).
+// (FreeBSD, OpenBSD and NetBSD-specific parts).
 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_platform.h"
-#if SANITIZER_FREEBSD || SANITIZER_NETBSD
+#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD
 #include "sanitizer_common.h"
 #if SANITIZER_FREEBSD
 #include "sanitizer_freebsd.h"
@@ -28,6 +28,11 @@
 #endif
 
 #include <limits.h>
+#if SANITIZER_OPENBSD
+#define KVME_PROT_READ KVE_PROT_READ
+#define KVME_PROT_WRITE KVE_PROT_WRITE
+#define KVME_PROT_EXEC KVE_PROT_EXEC
+#endif
 
 // Fix 'kinfo_vmentry' definition on FreeBSD prior v9.2 in 32-bit mode.
 #if SANITIZER_FREEBSD && (SANITIZER_WORDSIZE == 32)
@@ -46,6 +51,10 @@ void ReadProcMaps(ProcSelfMapsBuff *proc_maps) {
     KERN_PROC,
     KERN_PROC_VMMAP,
     getpid()
+#elif SANITIZER_OPENBSD
+    CTL_KERN,
+    KERN_PROC_VMMAP,
+    getpid()
 #elif SANITIZER_NETBSD
     CTL_VM,
     VM_PROC,
@@ -62,12 +71,28 @@ void ReadProcMaps(ProcSelfMapsBuff *proc_maps) {
   CHECK_EQ(Err, 0);
   CHECK_GT(Size, 0);
 
+#if !SANITIZER_OPENBSD
   size_t MmapedSize = Size * 4 / 3;
   void *VmMap = MmapOrDie(MmapedSize, "ReadProcMaps()");
   Size = MmapedSize;
   Err = internal_sysctl(Mib, ARRAY_SIZE(Mib), VmMap, &Size, NULL, 0);
   CHECK_EQ(Err, 0);
   proc_maps->data = (char *)VmMap;
+#else
+  size_t PageSize = GetPageSize();
+  size_t MmapedSize = Size;
+  MmapedSize = ((MmapedSize - 1) / PageSize + 1) * PageSize;
+  char *Mem = (char *)MmapOrDie(MmapedSize, "ReadProcMaps()");
+  Size = 2 * Size + 10 * sizeof(struct kinfo_vmentry);
+  if (Size > 0x10000)
+    Size = 0x10000;
+  Size = (Size / sizeof(struct kinfo_vmentry)) * sizeof(struct kinfo_vmentry);
+  Err = internal_sysctl(Mib, ARRAY_SIZE(Mib), Mem, &Size, NULL, 0);
+  CHECK_EQ(Err, 0);
+  MmapedSize = Size;
+  proc_maps->data = Mem;
+#endif
+
   proc_maps->mmaped_size = MmapedSize;
   proc_maps->len = Size;
 }
@@ -92,11 +117,13 @@ bool MemoryMappingLayout::Next(MemoryMappedSegment *segment) {
   if ((VmEntry->kve_protection & KVME_PROT_EXEC) != 0)
     segment->protection |= kProtectionExecute;
 
+#if !SANITIZER_OPENBSD
   if (segment->filename != NULL && segment->filename_size > 0) {
     internal_snprintf(segment->filename,
                       Min(segment->filename_size, (uptr)PATH_MAX), "%s",
                       VmEntry->kve_path);
   }
+#endif
 
 #if SANITIZER_FREEBSD
   data_.current += VmEntry->kve_structsize;
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_common.cpp b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_common.cpp
index f2cfcffaf47..e0cb47f8ca9 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_common.cpp
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_procmaps_common.cpp
@@ -12,7 +12,7 @@
 #include "sanitizer_platform.h"
 
 #if SANITIZER_FREEBSD || SANITIZER_LINUX || SANITIZER_NETBSD ||                \
-    SANITIZER_SOLARIS
+    SANITIZER_OPENBSD || SANITIZER_SOLARIS
 
 #include "sanitizer_common.h"
 #include "sanitizer_placement_new.h"
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
index 0350fe84b04..d9fd88d90a7 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_stacktrace.h
@@ -25,6 +25,8 @@ static const u32 kStackTraceMax = 256;
 # define SANITIZER_CAN_FAST_UNWIND 0
 #elif SANITIZER_WINDOWS
 # define SANITIZER_CAN_FAST_UNWIND 0
+#elif SANITIZER_OPENBSD
+# define SANITIZER_CAN_FAST_UNWIND 0
 #else
 # define SANITIZER_CAN_FAST_UNWIND 1
 #endif
@@ -32,7 +34,7 @@ static const u32 kStackTraceMax = 256;
 // Fast unwind is the only option on Mac for now; we will need to
 // revisit this macro when slow unwind works on Mac, see
 // https://github.com/google/sanitizers/issues/137
-#if SANITIZER_MAC || SANITIZER_RTEMS
+#if SANITIZER_MAC || SANITIZER_OPENBSD || SANITIZER_RTEMS
 # define SANITIZER_CAN_SLOW_UNWIND 0
 #else
 # define SANITIZER_CAN_SLOW_UNWIND 1
diff --git a/compiler-rt/lib/sanitizer_common/sanitizer_syscall_generic.inc b/compiler-rt/lib/sanitizer_common/sanitizer_syscall_generic.inc
index 8829985b5b0..a43ce3efab1 100644
--- a/compiler-rt/lib/sanitizer_common/sanitizer_syscall_generic.inc
+++ b/compiler-rt/lib/sanitizer_common/sanitizer_syscall_generic.inc
@@ -13,7 +13,7 @@
 // NetBSD uses libc calls directly
 #if !SANITIZER_NETBSD
 
-#if SANITIZER_FREEBSD || SANITIZER_MAC || SANITIZER_SOLARIS
+#if SANITIZER_FREEBSD || SANITIZER_MAC || SANITIZER_OPENBSD || SANITIZER_SOLARIS
 # define SYSCALL(name) SYS_ ## name
 #else
 # define SYSCALL(name) __NR_ ## name
diff --git a/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp b/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
index 259bd99324a..212d2f56ff8 100644
--- a/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
+++ b/compiler-rt/lib/sanitizer_common/tests/sanitizer_common_test.cpp
@@ -354,7 +354,7 @@ TEST(SanitizerCommon, InternalScopedString) {
 }
 
 #if SANITIZER_LINUX || SANITIZER_FREEBSD || \
-  SANITIZER_MAC || SANITIZER_IOS
+  SANITIZER_OPENBSD || SANITIZER_MAC || SANITIZER_IOS
 TEST(SanitizerCommon, GetRandom) {
   u8 buffer_1[32], buffer_2[32];
   for (bool blocking : { false, true }) {
diff --git a/compiler-rt/lib/tsan/go/buildgo.sh b/compiler-rt/lib/tsan/go/buildgo.sh
index 4cfbeff8b4c..e9b4b4c9f9c 100755
--- a/compiler-rt/lib/tsan/go/buildgo.sh
+++ b/compiler-rt/lib/tsan/go/buildgo.sh
@@ -108,6 +108,27 @@ elif [ "`uname -a | grep NetBSD`" != "" ]; then
 		../../sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp
 		../../sanitizer_common/sanitizer_stoptheworld_netbsd_libcdep.cpp
 	"
+elif [ "`uname -a | grep OpenBSD`" != "" ]; then
+	# The resulting object still depends on libc.
+	# We removed this dependency for Go runtime for other OSes,
+	# and we should remove it for OpenBSD as well, but there is no pressing need.
+	DEPENDS_ON_LIBC=1
+	SUFFIX="openbsd_amd64"
+	OSCFLAGS="-fno-strict-aliasing -fPIC -Werror"
+	ARCHCFLAGS="-m64"
+	OSLDFLAGS="-pthread -fPIC -fpie"
+	SRCS="
+		$SRCS
+		../rtl/tsan_platform_linux.cpp
+		../../sanitizer_common/sanitizer_posix.cpp
+		../../sanitizer_common/sanitizer_posix_libcdep.cpp
+		../../sanitizer_common/sanitizer_procmaps_bsd.cpp
+		../../sanitizer_common/sanitizer_procmaps_common.cpp
+		../../sanitizer_common/sanitizer_linux.cpp
+		../../sanitizer_common/sanitizer_linux_libcdep.cpp
+		../../sanitizer_common/sanitizer_openbsd.cpp
+		../../sanitizer_common/sanitizer_stoptheworld_linux_libcdep.cpp
+	"
 elif [ "`uname -a | grep Darwin`" != "" ]; then
 	SUFFIX="darwin_amd64"
 	OSCFLAGS="-fPIC -Wno-unused-const-variable -Wno-unknown-warning-option -mmacosx-version-min=10.7"
diff --git a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
index d136dcb1cec..710e7ec97b7 100644
--- a/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
+++ b/compiler-rt/lib/tsan/rtl/tsan_platform_linux.cpp
@@ -12,12 +12,14 @@
 //===----------------------------------------------------------------------===//
 
 #include "sanitizer_common/sanitizer_platform.h"
-#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD
+#if SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD || \
+    SANITIZER_OPENBSD
 
 #include "sanitizer_common/sanitizer_common.h"
 #include "sanitizer_common/sanitizer_libc.h"
 #include "sanitizer_common/sanitizer_linux.h"
 #include "sanitizer_common/sanitizer_platform_limits_netbsd.h"
+#include "sanitizer_common/sanitizer_platform_limits_openbsd.h"
 #include "sanitizer_common/sanitizer_platform_limits_posix.h"
 #include "sanitizer_common/sanitizer_posix.h"
 #include "sanitizer_common/sanitizer_procmaps.h"
@@ -515,4 +517,5 @@ void cur_thread_finalize() {
 
 }  // namespace __tsan
 
-#endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD
+#endif  // SANITIZER_LINUX || SANITIZER_FREEBSD || SANITIZER_NETBSD ||
+        // SANITIZER_OPENBSD
diff --git a/compiler-rt/lib/ubsan/ubsan_platform.h b/compiler-rt/lib/ubsan/ubsan_platform.h
index 32d949d75b9..71d7fb18c9b 100644
--- a/compiler-rt/lib/ubsan/ubsan_platform.h
+++ b/compiler-rt/lib/ubsan/ubsan_platform.h
@@ -14,7 +14,7 @@
 
 // Other platforms should be easy to add, and probably work as-is.
 #if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__) ||        \
-    defined(__NetBSD__) || \
+    defined(__NetBSD__) || defined(__OpenBSD__) || \
     (defined(__sun__) && defined(__svr4__)) || \
     defined(_WIN32) || defined(__Fuchsia__) || defined(__rtems__)
 # define CAN_SANITIZE_UB 1
diff --git a/compiler-rt/lib/xray/xray_basic_logging.cpp b/compiler-rt/lib/xray/xray_basic_logging.cpp
index a58ae9b5e26..6e8e9313145 100644
--- a/compiler-rt/lib/xray/xray_basic_logging.cpp
+++ b/compiler-rt/lib/xray/xray_basic_logging.cpp
@@ -18,7 +18,7 @@
 #include <fcntl.h>
 #include <pthread.h>
 #include <sys/stat.h>
-#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_MAC
+#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD || SANITIZER_MAC
 #include <sys/syscall.h>
 #endif
 #include <sys/types.h>
diff --git a/compiler-rt/lib/xray/xray_x86_64.cpp b/compiler-rt/lib/xray/xray_x86_64.cpp
index c58584b3a14..f3742ac7129 100644
--- a/compiler-rt/lib/xray/xray_x86_64.cpp
+++ b/compiler-rt/lib/xray/xray_x86_64.cpp
@@ -6,8 +6,12 @@
 #include "xray_defs.h"
 #include "xray_interface_internal.h"
 
-#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_MAC
+#if SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD || SANITIZER_MAC
 #include <sys/types.h>
+#if SANITIZER_OPENBSD
+#include <sys/time.h>
+#include <machine/cpu.h>
+#endif
 #include <sys/sysctl.h>
 #elif SANITIZER_FUCHSIA
 #include <zircon/syscalls.h>
@@ -82,11 +86,14 @@ uint64_t getTSCFrequency() XRAY_NEVER_INSTRUMENT {
   }
   return TSCFrequency == -1 ? 0 : static_cast<uint64_t>(TSCFrequency);
 }
-#elif SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_MAC
+#elif SANITIZER_FREEBSD || SANITIZER_NETBSD || SANITIZER_OPENBSD || SANITIZER_MAC
 uint64_t getTSCFrequency() XRAY_NEVER_INSTRUMENT {
     long long TSCFrequency = -1;
     size_t tscfreqsz = sizeof(TSCFrequency);
-#if SANITIZER_MAC
+#if SANITIZER_OPENBSD
+    int Mib[2] = { CTL_MACHDEP, CPU_TSCFREQ };
+    if (internal_sysctl(Mib, 2, &TSCFrequency, &tscfreqsz, NULL, 0) != -1) {
+#elif SANITIZER_MAC
     if (internal_sysctlbyname("machdep.tsc.frequency", &TSCFrequency,
                               &tscfreqsz, NULL, 0) != -1) {