diff --git a/common/bloblist.c b/common/bloblist.c
index eab63e9ca51..bb49ecab92e 100644
--- a/common/bloblist.c
+++ b/common/bloblist.c
@@ -57,13 +57,22 @@ static struct bloblist_rec *bloblist_first_blob(struct bloblist_hdr *hdr)
 	return (struct bloblist_rec *)((void *)hdr + hdr->hdr_size);
 }
 
-static struct bloblist_rec *bloblist_next_blob(struct bloblist_hdr *hdr,
-					       struct bloblist_rec *rec)
+static ulong bloblist_blob_end_ofs(struct bloblist_hdr *hdr,
+				   struct bloblist_rec *rec)
 {
 	ulong offset;
 
 	offset = (void *)rec - (void *)hdr;
 	offset += rec->hdr_size + ALIGN(rec->size, BLOBLIST_ALIGN);
+
+	return offset;
+}
+
+static struct bloblist_rec *bloblist_next_blob(struct bloblist_hdr *hdr,
+					       struct bloblist_rec *rec)
+{
+	ulong offset = bloblist_blob_end_ofs(hdr, rec);
+
 	if (offset >= hdr->alloced)
 		return NULL;
 	return (struct bloblist_rec *)((void *)hdr + offset);
@@ -215,6 +224,64 @@ int bloblist_ensure_size_ret(uint tag, int *sizep, void **blobp)
 	return 0;
 }
 
+static int bloblist_resize_rec(struct bloblist_hdr *hdr,
+			       struct bloblist_rec *rec,
+			       int new_size)
+{
+	int expand_by;	/* Number of bytes to expand by (-ve to contract) */
+	int new_alloced;	/* New value for @hdr->alloced */
+	ulong next_ofs;	/* Offset of the record after @rec */
+
+	expand_by = ALIGN(new_size - rec->size, BLOBLIST_ALIGN);
+	new_alloced = ALIGN(hdr->alloced + expand_by, BLOBLIST_ALIGN);
+	if (new_size < 0) {
+		log(LOGC_BLOBLIST, LOGL_DEBUG,
+		    "Attempt to shrink blob size below 0 (%x)\n", new_size);
+		return log_msg_ret("size", -EINVAL);
+	}
+	if (new_alloced > hdr->size) {
+		log(LOGC_BLOBLIST, LOGL_ERR,
+		    "Failed to allocate %x bytes size=%x, need size=%x\n",
+		    new_size, hdr->size, new_alloced);
+		return log_msg_ret("alloc", -ENOSPC);
+	}
+
+	/* Move the following blobs up or down, if this is not the last */
+	next_ofs = bloblist_blob_end_ofs(hdr, rec);
+	if (next_ofs != hdr->alloced) {
+		memmove((void *)hdr + next_ofs + expand_by,
+			(void *)hdr + next_ofs, new_alloced - next_ofs);
+	}
+	hdr->alloced = new_alloced;
+
+	/* Zero the new part of the blob */
+	if (expand_by > 0) {
+		memset((void *)rec + rec->hdr_size + rec->size, '\0',
+		       new_size - rec->size);
+	}
+
+	/* Update the size of this blob */
+	rec->size = new_size;
+
+	return 0;
+}
+
+int bloblist_resize(uint tag, int new_size)
+{
+	struct bloblist_hdr *hdr = gd->bloblist;
+	struct bloblist_rec *rec;
+	int ret;
+
+	rec = bloblist_findrec(tag);
+	if (!rec)
+		return log_msg_ret("find", -ENOENT);
+	ret = bloblist_resize_rec(hdr, rec, new_size);
+	if (ret)
+		return log_msg_ret("resize", ret);
+
+	return 0;
+}
+
 static u32 bloblist_calc_chksum(struct bloblist_hdr *hdr)
 {
 	struct bloblist_rec *rec;
diff --git a/include/bloblist.h b/include/bloblist.h
index 964b974fdaf..b659d2bc93d 100644
--- a/include/bloblist.h
+++ b/include/bloblist.h
@@ -179,6 +179,19 @@ void *bloblist_ensure(uint tag, int size);
  */
 int bloblist_ensure_size_ret(uint tag, int *sizep, void **blobp);
 
+/**
+ * bloblist_resize() - resize a blob
+ *
+ * Any blobs above this one are relocated up or down. The resized blob remains
+ * in the same place.
+ *
+ * @tag:	Tag to add (enum bloblist_tag_t)
+ * @new_size:	New size of the blob (>0 to expand, <0 to contract)
+ * @return 0 if OK, -ENOSPC if the bloblist does not have enough space, -ENOENT
+ *	if the tag is not found
+ */
+int bloblist_resize(uint tag, int new_size);
+
 /**
  * bloblist_new() - Create a new, empty bloblist of a given size
  *
diff --git a/test/bloblist.c b/test/bloblist.c
index d876b639184..345eb181fff 100644
--- a/test/bloblist.c
+++ b/test/bloblist.c
@@ -33,6 +33,9 @@ enum {
 	ERASE_BYTE		= '\xff',
 };
 
+static const char test1_str[] = "the eyes are open";
+static const char test2_str[] = "the mouth moves";
+
 static struct bloblist_hdr *clear_bloblist(void)
 {
 	struct bloblist_hdr *hdr;
@@ -384,6 +387,195 @@ static int bloblist_test_reloc(struct unit_test_state *uts)
 }
 BLOBLIST_TEST(bloblist_test_reloc, 0);
 
+/* Test expansion of a blob */
+static int bloblist_test_grow(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	void *blob1, *blob2, *blob1_new;
+	struct bloblist_hdr *hdr;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+	hdr = ptr;
+	memset(hdr, ERASE_BYTE, TEST_BLOBLIST_SIZE);
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+	ut_assertok(check_zero(blob1, small_size));
+	strcpy(blob1, test1_str);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+	strcpy(blob2, test2_str);
+
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2,
+		    hdr->alloced);
+
+	/* Resize the first one */
+	ut_assertok(bloblist_resize(TEST_TAG, small_size + 4));
+
+	/* The first one should not have moved, just got larger */
+	blob1_new = bloblist_find(TEST_TAG, small_size + 4);
+	ut_asserteq_ptr(blob1, blob1_new);
+
+	/* The new space should be zeroed */
+	ut_assertok(check_zero(blob1 + small_size, 4));
+
+	/* The second one should have moved */
+	blob2 = bloblist_find(TEST_TAG2, small_size);
+	ut_assertnonnull(blob2);
+	ut_asserteq_str(test2_str, blob2);
+
+	/* The header should have more bytes in use */
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2 +
+		    BLOBLIST_ALIGN,
+		    hdr->alloced);
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_grow, 0);
+
+/* Test shrinking of a blob */
+static int bloblist_test_shrink(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	void *blob1, *blob2, *blob1_new;
+	struct bloblist_hdr *hdr;
+	int new_size;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+	strcpy(blob1, test1_str);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+	strcpy(blob2, test2_str);
+
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2,
+		    hdr->alloced);
+
+	/* Resize the first one */
+	new_size = small_size - BLOBLIST_ALIGN - 4;
+	ut_assertok(bloblist_resize(TEST_TAG, new_size));
+
+	/* The first one should not have moved, just got smaller */
+	blob1_new = bloblist_find(TEST_TAG, new_size);
+	ut_asserteq_ptr(blob1, blob1_new);
+
+	/* The second one should have moved */
+	blob2 = bloblist_find(TEST_TAG2, small_size);
+	ut_assertnonnull(blob2);
+	ut_asserteq_str(test2_str, blob2);
+
+	/* The header should have fewer bytes in use */
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2 -
+		    BLOBLIST_ALIGN,
+		    hdr->alloced);
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_shrink, 0);
+
+/* Test failing to adjust a blob size */
+static int bloblist_test_resize_fail(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	struct bloblist_hdr *hdr;
+	void *blob1, *blob2;
+	int new_size;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+
+	hdr = ptr;
+	ut_asserteq(sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2,
+		    hdr->alloced);
+
+	/* Resize the first one, to check the boundary conditions */
+	ut_asserteq(-EINVAL, bloblist_resize(TEST_TAG, -1));
+
+	new_size = small_size + (hdr->size - hdr->alloced);
+	ut_asserteq(-ENOSPC, bloblist_resize(TEST_TAG, new_size + 1));
+	ut_assertok(bloblist_resize(TEST_TAG, new_size));
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_resize_fail, 0);
+
+/* Test expanding the last blob in a bloblist */
+static int bloblist_test_resize_last(struct unit_test_state *uts)
+{
+	const uint small_size = 0x20;
+	struct bloblist_hdr *hdr;
+	void *blob1, *blob2, *blob2_new;
+	int alloced_val;
+	void *ptr;
+
+	ptr = map_sysmem(TEST_ADDR, TEST_BLOBLIST_SIZE);
+	memset(ptr, ERASE_BYTE, TEST_BLOBLIST_SIZE);
+	hdr = ptr;
+
+	/* Create two blobs */
+	ut_assertok(bloblist_new(TEST_ADDR, TEST_BLOBLIST_SIZE, 0));
+	blob1 = bloblist_add(TEST_TAG, small_size, 0);
+	ut_assertnonnull(blob1);
+
+	blob2 = bloblist_add(TEST_TAG2, small_size, 0);
+	ut_assertnonnull(blob2);
+
+	/* Check the byte after the last blob */
+	alloced_val = sizeof(struct bloblist_hdr) +
+		    sizeof(struct bloblist_rec) * 2 + small_size * 2;
+	ut_asserteq(alloced_val, hdr->alloced);
+	ut_asserteq_ptr((void *)hdr + alloced_val, blob2 + small_size);
+	ut_asserteq((u8)ERASE_BYTE, *((u8 *)hdr + hdr->alloced));
+
+	/* Resize the second one, checking nothing changes */
+	ut_asserteq(0, bloblist_resize(TEST_TAG2, small_size + 4));
+
+	blob2_new = bloblist_find(TEST_TAG2, small_size + 4);
+	ut_asserteq_ptr(blob2, blob2_new);
+
+	/*
+	 * the new blob should encompass the byte we checked now, so it should
+	 * be zeroed. This zeroing should affect only the four new bytes added
+	 * to the blob.
+	 */
+	ut_asserteq(0, *((u8 *)hdr + alloced_val));
+	ut_asserteq((u8)ERASE_BYTE, *((u8 *)hdr + alloced_val + 4));
+
+	/* Check that the new top of the allocated blobs has not been touched */
+	alloced_val += BLOBLIST_ALIGN;
+	ut_asserteq(alloced_val, hdr->alloced);
+	ut_asserteq((u8)ERASE_BYTE, *((u8 *)hdr + hdr->alloced));
+
+	return 0;
+}
+BLOBLIST_TEST(bloblist_test_resize_last, 0);
+
 int do_ut_bloblist(struct cmd_tbl *cmdtp, int flag, int argc,
 		   char *const argv[])
 {