diff --git a/lib/isc/include/isc/mem.h b/lib/isc/include/isc/mem.h
index 0e0d24a3b1..a513890cc7 100644
--- a/lib/isc/include/isc/mem.h
+++ b/lib/isc/include/isc/mem.h
@@ -134,7 +134,9 @@ extern unsigned int isc_mem_defaultflags;
 #define ISCMEMFUNC(sfx)	    isc__mem_##sfx
 #define ISCMEMPOOLFUNC(sfx) isc__mempool_##sfx
 
-#define isc_mem_get(c, s)      ISCMEMFUNC(get)((c), (s)_ISC_MEM_FILELINE)
+#define isc_mem_get(c, s) ISCMEMFUNC(get)((c), (s)_ISC_MEM_FILELINE)
+#define isc_mem_reget(c, p, o, n) \
+	ISCMEMFUNC(reget)((c), (p), (o), (n)_ISC_MEM_FILELINE)
 #define isc_mem_allocate(c, s) ISCMEMFUNC(allocate)((c), (s)_ISC_MEM_FILELINE)
 #define isc_mem_reallocate(c, p, s) \
 	ISCMEMFUNC(reallocate)((c), (p), (s)_ISC_MEM_FILELINE)
@@ -483,6 +485,9 @@ void ISCMEMFUNC(free)(isc_mem_t *, void *_ISC_MEM_FLARG);
 ISC_ATTR_MALLOC_DEALLOCATOR_IDX(ISCMEMFUNC(put), 2)
 void *ISCMEMFUNC(get)(isc_mem_t *, size_t _ISC_MEM_FLARG);
 
+ISC_ATTR_DEALLOCATOR_IDX(ISCMEMFUNC(put), 2)
+void *ISCMEMFUNC(reget)(isc_mem_t *, void *, size_t, size_t _ISC_MEM_FLARG);
+
 ISC_ATTR_MALLOC_DEALLOCATOR_IDX(ISCMEMFUNC(free), 2)
 void *ISCMEMFUNC(allocate)(isc_mem_t *, size_t _ISC_MEM_FLARG);
 
diff --git a/lib/isc/mem.c b/lib/isc/mem.c
index e598afce8b..c368959fa7 100644
--- a/lib/isc/mem.c
+++ b/lib/isc/mem.c
@@ -349,6 +349,24 @@ mem_put(isc_mem_t *ctx, void *mem, size_t size) {
 	sdallocx(mem, size, 0);
 }
 
+static inline void *
+mem_realloc(isc_mem_t *ctx, void *old_ptr, size_t old_size, size_t new_size) {
+	void *new_ptr = NULL;
+
+	new_ptr = rallocx(old_ptr, new_size, 0);
+
+	if (ISC_UNLIKELY((ctx->flags & ISC_MEMFLAG_FILL) != 0)) {
+		ssize_t diff_size = new_size - old_size;
+		void *diff_ptr = (uint8_t *)new_ptr + old_size;
+		if (diff_size > 0) {
+			/* Mnemonic for "beef". */
+			memset(diff_ptr, 0xbe, diff_size);
+		}
+	}
+
+	return (new_ptr);
+}
+
 #define stats_bucket(ctx, size)                      \
 	((size / STATS_BUCKET_SIZE) >= STATS_BUCKETS \
 		 ? &ctx->stats[STATS_BUCKETS]        \
@@ -872,6 +890,37 @@ isc__mem_allocate(isc_mem_t *ctx, size_t size FLARG) {
 	return (ptr);
 }
 
+void *
+isc__mem_reget(isc_mem_t *ctx, void *old_ptr, size_t old_size,
+	       size_t new_size FLARG) {
+	void *new_ptr = NULL;
+
+	if (ISC_UNLIKELY(old_ptr == NULL)) {
+		REQUIRE(old_size == 0);
+		new_ptr = isc__mem_get(ctx, new_size FLARG_PASS);
+	} else if (ISC_UNLIKELY(new_size == 0)) {
+		isc__mem_put(ctx, old_ptr, old_size FLARG_PASS);
+	} else {
+		DELETE_TRACE(ctx, old_ptr, old_size, file, line);
+		mem_putstats(ctx, old_ptr, old_size);
+
+		new_ptr = mem_realloc(ctx, old_ptr, old_size, new_size);
+
+		mem_getstats(ctx, new_size);
+		ADD_TRACE(ctx, new_ptr, new_size, file, line);
+
+		/*
+		 * We want to postpone the call to water in edge case
+		 * where the realloc will exactly hit on the boundary of
+		 * the water and we would call water twice.
+		 */
+		CALL_LO_WATER(ctx);
+		CALL_HI_WATER(ctx);
+	}
+
+	return (new_ptr);
+}
+
 void *
 isc__mem_reallocate(isc_mem_t *ctx, void *old_ptr, size_t new_size FLARG) {
 	void *new_ptr = NULL;
@@ -888,16 +937,7 @@ isc__mem_reallocate(isc_mem_t *ctx, void *old_ptr, size_t new_size FLARG) {
 		DELETE_TRACE(ctx, old_ptr, old_size, file, line);
 		mem_putstats(ctx, old_ptr, old_size);
 
-		new_ptr = rallocx(old_ptr, new_size, 0);
-
-		if (ISC_UNLIKELY((ctx->flags & ISC_MEMFLAG_FILL) != 0)) {
-			ssize_t diff_size = new_size - old_size;
-			void *diff_ptr = (uint8_t *)new_ptr + old_size;
-			if (diff_size >= 0) {
-				/* Mnemonic for "beef". */
-				memset(diff_ptr, 0xbe, diff_size);
-			}
-		}
+		new_ptr = mem_realloc(ctx, old_ptr, old_size, new_size);
 
 		/* Recalculate the real allocated size */
 		new_size = sallocx(new_ptr, 0);
diff --git a/lib/isc/tests/mem_test.c b/lib/isc/tests/mem_test.c
index e848200e2a..d5b46f2a1b 100644
--- a/lib/isc/tests/mem_test.c
+++ b/lib/isc/tests/mem_test.c
@@ -220,6 +220,40 @@ isc_mem_inuse_test(void **state) {
 	isc_mem_destroy(&mctx2);
 }
 
+#define REGET_INIT_SIZE	  1024
+#define REGET_GROW_SIZE	  2048
+#define REGET_SHRINK_SIZE 512
+
+static void
+isc_mem_reget_test(void **state) {
+	uint8_t *data = isc_mem_get(test_mctx, REGET_INIT_SIZE);
+
+	UNUSED(state);
+
+	for (size_t i = 0; i < REGET_INIT_SIZE; i++) {
+		data[i] = i % UINT8_MAX;
+	}
+
+	data = isc_mem_reget(test_mctx, data, REGET_INIT_SIZE, REGET_GROW_SIZE);
+
+	for (size_t i = 0; i < REGET_INIT_SIZE; i++) {
+		assert_int_equal(data[i], i % UINT8_MAX);
+	}
+
+	for (size_t i = REGET_GROW_SIZE; i > 0; i--) {
+		data[i - 1] = i % UINT8_MAX;
+	}
+
+	data = isc_mem_reget(test_mctx, data, REGET_GROW_SIZE,
+			     REGET_SHRINK_SIZE);
+
+	for (size_t i = REGET_SHRINK_SIZE; i > 0; i--) {
+		assert_int_equal(data[i - 1], i % UINT8_MAX);
+	}
+
+	isc_mem_put(test_mctx, data, REGET_SHRINK_SIZE);
+}
+
 #if ISC_MEM_TRACKLINES
 
 /* test mem with no flags */
@@ -436,6 +470,8 @@ main(void) {
 						_teardown),
 		cmocka_unit_test_setup_teardown(isc_mem_inuse_test, _setup,
 						_teardown),
+		cmocka_unit_test_setup_teardown(isc_mem_reget_test, _setup,
+						_teardown),
 
 #if !defined(__SANITIZE_THREAD__)
 		cmocka_unit_test_setup_teardown(isc_mem_benchmark, _setup,