diff --git a/.github/workflows/llm-fuzzer.yaml b/.github/workflows/llm-fuzzer.yaml
index 8a4b925cdd9..8d713a3c546 100644
--- a/.github/workflows/llm-fuzzer.yaml
+++ b/.github/workflows/llm-fuzzer.yaml
@@ -123,7 +123,9 @@ jobs:
         # Add instrumentation to the Postgres memory contexts. For more details, see
         # https://github.com/timescale/eng-database/wiki/Using-Address-Sanitizer#adding-more-instrumentation
         PG_MAJOR=$(echo "${{ needs.config.outputs.pg_latest }}" | sed -e 's![.].*!!')
-        if [ ${PG_MAJOR} -lt 18 ]; then
+        if [ ${PG_MAJOR} -lt 16 ]; then
+          patch -F5 -p1 -d ~/$PG_SRC_DIR < test/postgres-asan-instrumentation-PG15.patch
+        elif [ ${PG_MAJOR} -lt 18 ]; then
           patch -F5 -p1 -d ~/$PG_SRC_DIR < test/postgres-asan-instrumentation.patch
         else
           patch -F5 -p1 -d ~/$PG_SRC_DIR < test/postgres-asan-instrumentation-PG18GE.patch
diff --git a/.github/workflows/sanitizer-build-and-test.yaml b/.github/workflows/sanitizer-build-and-test.yaml
index cb3167e75c9..6ab564b39c7 100644
--- a/.github/workflows/sanitizer-build-and-test.yaml
+++ b/.github/workflows/sanitizer-build-and-test.yaml
@@ -125,7 +125,9 @@ jobs:
         # Add instrumentation to the Postgres memory contexts. For more details, see
         # https://github.com/timescale/eng-database/wiki/Using-Address-Sanitizer#adding-more-instrumentation
         PG_MAJOR=$(echo "${{ matrix.pg }}" | sed -e 's![.].*!!')
-        if [ ${PG_MAJOR} -lt 18 ]; then
+        if [ ${PG_MAJOR} -lt 16 ]; then
+          patch -F5 -p1 -d ~/$PG_SRC_DIR < test/postgres-asan-instrumentation-PG15.patch
+        elif [ ${PG_MAJOR} -lt 18 ]; then
           patch -F5 -p1 -d ~/$PG_SRC_DIR < test/postgres-asan-instrumentation.patch
         else
           patch -F5 -p1 -d ~/$PG_SRC_DIR < test/postgres-asan-instrumentation-PG18GE.patch
diff --git a/test/postgres-asan-instrumentation-PG15.patch b/test/postgres-asan-instrumentation-PG15.patch
new file mode 100644
index 00000000000..31d70b331e5
--- /dev/null
+++ b/test/postgres-asan-instrumentation-PG15.patch
@@ -0,0 +1,68 @@
+diff --git a/src/backend/tcop/postgres.c b/src/backend/tcop/postgres.c
+index 2c50575b37..11b6c688c7 100644
+--- a/src/backend/tcop/postgres.c
++++ b/src/backend/tcop/postgres.c
+@@ -3492,6 +4476,12 @@ check_stack_depth(void)
+ bool
+ stack_is_too_deep(void)
+ {
++	/*
++	 * Pointer arithmetics to determine stack depth doesn't work under
++	 * AddressSanitizer.
++	 */
++	return false;
++
+ 	char		stack_top_loc;
+ 	long		stack_depth;
+
+diff --git a/src/include/utils/memdebug.h b/src/include/utils/memdebug.h
+index e88b4c6e8e..4ccbbf0146 100644
+--- a/src/include/utils/memdebug.h
++++ b/src/include/utils/memdebug.h
+@@ -19,6 +19,31 @@
+
+ #ifdef USE_VALGRIND
+ #include <valgrind/memcheck.h>
++
++#elif __has_feature(address_sanitizer) || defined(__SANITIZE_ADDRESS__)
++
++#include <sanitizer/asan_interface.h>
++
++#define VALGRIND_MAKE_MEM_DEFINED(addr, size) \
++ ASAN_UNPOISON_MEMORY_REGION(addr, size)
++
++#define VALGRIND_MAKE_MEM_NOACCESS(addr, size) \
++ ASAN_POISON_MEMORY_REGION(addr, size)
++
++#define VALGRIND_MAKE_MEM_UNDEFINED(addr, size) \
++ ASAN_UNPOISON_MEMORY_REGION(addr, size)
++
++#define VALGRIND_MEMPOOL_ALLOC(context, addr, size) \
++ ASAN_UNPOISON_MEMORY_REGION(addr, size)
++
++#define VALGRIND_MEMPOOL_FREE(context, addr) \
++ ASAN_POISON_MEMORY_REGION(addr, 1 /* Length unknown, poison first byte. */)
++
++#define VALGRIND_CHECK_MEM_IS_DEFINED(addr, size) do {} while (0)
++#define VALGRIND_CREATE_MEMPOOL(context, redzones, zeroed) do {} while (0)
++#define VALGRIND_DESTROY_MEMPOOL(context) do {} while (0)
++#define VALGRIND_MEMPOOL_CHANGE(context, optr, nptr, size) do {} while (0)
++
+ #else
+ #define VALGRIND_CHECK_MEM_IS_DEFINED(addr, size)			do {} while (0)
+ #define VALGRIND_CREATE_MEMPOOL(context, redzones, zeroed)	do {} while (0)
+diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
+--- a/src/backend/utils/mmgr/aset.c
++++ b/src/backend/utils/mmgr/aset.c
+@@ -1267,11 +1267,9 @@
+ 		 * Make sure not to mark too many bytes in case chunk->requested_size
+ 		 * < size < oldchksize.
+ 		 */
+-#ifdef USE_VALGRIND
+ 		if (Min(size, oldchksize) > chunk->requested_size)
+ 			VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + chunk->requested_size,
+ 										Min(size, oldchksize) - chunk->requested_size);
+-#endif
+ #endif
+
+ 		chunk->requested_size = size;
diff --git a/test/postgres-asan-instrumentation-PG18GE.patch b/test/postgres-asan-instrumentation-PG18GE.patch
index 5dc83af3ec4..6f6cfd663f2 100644
--- a/test/postgres-asan-instrumentation-PG18GE.patch
+++ b/test/postgres-asan-instrumentation-PG18GE.patch
@@ -20,7 +20,7 @@ index e88b4c6e8e..4ccbbf0146 100644
 --- a/src/include/utils/memdebug.h
 +++ b/src/include/utils/memdebug.h
 @@ -19,6 +19,31 @@
- 
+
  #ifdef USE_VALGRIND
  #include <valgrind/memcheck.h>
 +
@@ -51,3 +51,73 @@ index e88b4c6e8e..4ccbbf0146 100644
  #else
  #define VALGRIND_CHECK_MEM_IS_DEFINED(addr, size)			do {} while (0)
  #define VALGRIND_CREATE_MEMPOOL(context, redzones, zeroed)	do {} while (0)
+diff --git a/src/backend/utils/mmgr/mcxt.c b/src/backend/utils/mmgr/mcxt.c
+--- a/src/backend/utils/mmgr/mcxt.c
++++ b/src/backend/utils/mmgr/mcxt.c
+@@ -1549,17 +1549,13 @@
+ void
+ pfree(void *pointer)
+ {
+-#ifdef USE_VALGRIND
+ 	MemoryContextMethodID method = GetMemoryChunkMethodID(pointer);
+ 	MemoryContext context = GetMemoryChunkContext(pointer);
+-#endif
+
+ 	MCXT_METHOD(pointer, free_p) (pointer);
+
+-#ifdef USE_VALGRIND
+ 	if (method != MCTX_ALIGNED_REDIRECT_ID)
+ 		VALGRIND_MEMPOOL_FREE(context, pointer);
+-#endif
+ }
+
+ /*
+@@ -1569,12 +1565,8 @@
+ void *
+ repalloc(void *pointer, Size size)
+ {
+-#ifdef USE_VALGRIND
+ 	MemoryContextMethodID method = GetMemoryChunkMethodID(pointer);
+-#endif
+-#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
+ 	MemoryContext context = GetMemoryChunkContext(pointer);
+-#endif
+ 	void	   *ret;
+
+ 	AssertNotInCriticalSection(context);
+@@ -1597,10 +1589,8 @@
+ 	 */
+ 	ret = MCXT_METHOD(pointer, realloc) (pointer, size, 0);
+
+-#ifdef USE_VALGRIND
+ 	if (method != MCTX_ALIGNED_REDIRECT_ID)
+ 		VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
+-#endif
+
+ 	return ret;
+ }
+@@ -1613,9 +1603,7 @@
+ void *
+ repalloc_extended(void *pointer, Size size, int flags)
+ {
+-#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
+ 	MemoryContext context = GetMemoryChunkContext(pointer);
+-#endif
+ 	void	   *ret;
+
+ 	AssertNotInCriticalSection(context);
+diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
+--- a/src/backend/utils/mmgr/aset.c
++++ b/src/backend/utils/mmgr/aset.c
+@@ -1267,11 +1267,9 @@
+ 		 * Make sure not to mark too many bytes in case chunk->requested_size
+ 		 * < size < oldchksize.
+ 		 */
+-#ifdef USE_VALGRIND
+ 		if (Min(size, oldchksize) > chunk->requested_size)
+ 			VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + chunk->requested_size,
+ 										Min(size, oldchksize) - chunk->requested_size);
+-#endif
+ #endif
+
+ 		chunk->requested_size = size;
diff --git a/test/postgres-asan-instrumentation.patch b/test/postgres-asan-instrumentation.patch
index bc8f4e184b5..4b0100c4e6e 100644
--- a/test/postgres-asan-instrumentation.patch
+++ b/test/postgres-asan-instrumentation.patch
@@ -14,13 +14,13 @@ index 2c50575b37..11b6c688c7 100644
 +
  	char		stack_top_loc;
  	long		stack_depth;
- 
+
 diff --git a/src/include/utils/memdebug.h b/src/include/utils/memdebug.h
 index e88b4c6e8e..4ccbbf0146 100644
 --- a/src/include/utils/memdebug.h
 +++ b/src/include/utils/memdebug.h
 @@ -19,6 +19,31 @@
- 
+
  #ifdef USE_VALGRIND
  #include <valgrind/memcheck.h>
 +
@@ -51,3 +51,73 @@ index e88b4c6e8e..4ccbbf0146 100644
  #else
  #define VALGRIND_CHECK_MEM_IS_DEFINED(addr, size)			do {} while (0)
  #define VALGRIND_CREATE_MEMPOOL(context, redzones, zeroed)	do {} while (0)
+diff --git a/src/backend/utils/mmgr/mcxt.c b/src/backend/utils/mmgr/mcxt.c
+--- a/src/backend/utils/mmgr/mcxt.c
++++ b/src/backend/utils/mmgr/mcxt.c
+@@ -1549,17 +1549,13 @@
+ void
+ pfree(void *pointer)
+ {
+-#ifdef USE_VALGRIND
+ 	MemoryContextMethodID method = GetMemoryChunkMethodID(pointer);
+ 	MemoryContext context = GetMemoryChunkContext(pointer);
+-#endif
+
+ 	MCXT_METHOD(pointer, free_p) (pointer);
+
+-#ifdef USE_VALGRIND
+ 	if (method != MCTX_ALIGNED_REDIRECT_ID)
+ 		VALGRIND_MEMPOOL_FREE(context, pointer);
+-#endif
+ }
+
+ /*
+@@ -1569,12 +1565,8 @@
+ void *
+ repalloc(void *pointer, Size size)
+ {
+-#ifdef USE_VALGRIND
+ 	MemoryContextMethodID method = GetMemoryChunkMethodID(pointer);
+-#endif
+-#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
+ 	MemoryContext context = GetMemoryChunkContext(pointer);
+-#endif
+ 	void	   *ret;
+
+ 	AssertNotInCriticalSection(context);
+@@ -1597,10 +1589,8 @@
+ 	 */
+ 	ret = MCXT_METHOD(pointer, realloc) (pointer, size, 0);
+
+-#ifdef USE_VALGRIND
+ 	if (method != MCTX_ALIGNED_REDIRECT_ID)
+ 		VALGRIND_MEMPOOL_CHANGE(context, pointer, ret, size);
+-#endif
+
+ 	return ret;
+ }
+@@ -1613,9 +1603,7 @@
+ void *
+ repalloc_extended(void *pointer, Size size, int flags)
+ {
+-#if defined(USE_ASSERT_CHECKING) || defined(USE_VALGRIND)
+ 	MemoryContext context = GetMemoryChunkContext(pointer);
+-#endif
+ 	void	   *ret;
+
+ 	AssertNotInCriticalSection(context);
+diff --git a/src/backend/utils/mmgr/aset.c b/src/backend/utils/mmgr/aset.c
+--- a/src/backend/utils/mmgr/aset.c
++++ b/src/backend/utils/mmgr/aset.c
+@@ -1267,11 +1267,9 @@
+ 		 * Make sure not to mark too many bytes in case chunk->requested_size
+ 		 * < size < oldchksize.
+ 		 */
+-#ifdef USE_VALGRIND
+ 		if (Min(size, oldchksize) > chunk->requested_size)
+ 			VALGRIND_MAKE_MEM_UNDEFINED((char *) pointer + chunk->requested_size,
+ 										Min(size, oldchksize) - chunk->requested_size);
+-#endif
+ #endif
+
+ 		chunk->requested_size = size;