diff --git a/ld/ChangeLog b/ld/ChangeLog
index c9298e9400..d8b9a22485 100644
--- a/ld/ChangeLog
+++ b/ld/ChangeLog
@@ -1,3 +1,15 @@
+2017-04-04  Maciej W. Rozycki  <macro@imgtec.com>
+
+	PR ld/21233
+	* ldlang.c (insert_undefined): Set `mark' for ELF symbols.
+	* testsuite/ld-elf/pr21233.sd: New test.
+	* testsuite/ld-elf/pr21233-l.sd: New test.
+	* testsuite/ld-elf/pr21233.ld: New test linker script.
+	* testsuite/ld-elf/pr21233-e.ld: New test linker script.
+	* testsuite/ld-elf/pr21233.s: New test source.
+	* testsuite/ld-elf/pr21233-l.s: New test source.
+	* testsuite/ld-elf/shared.exp: Run the new tests.
+
 2017-04-04  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* NEWS: Mention support for ELF SHF_GNU_MBIND and
diff --git a/ld/ldlang.c b/ld/ldlang.c
index 5a42659674..266c099f5a 100644
--- a/ld/ldlang.c
+++ b/ld/ldlang.c
@@ -3429,6 +3429,8 @@ insert_undefined (const char *name)
     {
       h->type = bfd_link_hash_undefined;
       h->u.undef.abfd = NULL;
+      if (is_elf_hash_table (link_info.hash))
+	((struct elf_link_hash_entry *) h)->mark = 1;
       bfd_link_add_undef (link_info.hash, h);
     }
 }
diff --git a/ld/testsuite/ld-elf/pr21233-e.ld b/ld/testsuite/ld-elf/pr21233-e.ld
new file mode 100644
index 0000000000..f0bc2819e9
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr21233-e.ld
@@ -0,0 +1,2 @@
+EXTERN (bar)
+INCLUDE pr21233.ld
diff --git a/ld/testsuite/ld-elf/pr21233-l.s b/ld/testsuite/ld-elf/pr21233-l.s
new file mode 100644
index 0000000000..1d02f9aa5f
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr21233-l.s
@@ -0,0 +1,6 @@
+	.data
+	.globl	bar
+	.type	bar, %object
+bar:
+	.byte	1
+	.size	bar, . - bar
diff --git a/ld/testsuite/ld-elf/pr21233-l.sd b/ld/testsuite/ld-elf/pr21233-l.sd
new file mode 100644
index 0000000000..724fdd41d8
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr21233-l.sd
@@ -0,0 +1,6 @@
+# Make sure global `bar' is present in the dynamic symbol table, e.g.:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      1: 00000000     1 OBJECT  GLOBAL DEFAULT    5 bar
+#...
+ *[0-9]+: +[0-9a-f]+ +1 +OBJECT +GLOBAL +DEFAULT +[0-9]+ +bar
+#pass
diff --git a/ld/testsuite/ld-elf/pr21233.ld b/ld/testsuite/ld-elf/pr21233.ld
new file mode 100644
index 0000000000..a3b547bac4
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr21233.ld
@@ -0,0 +1,17 @@
+SECTIONS
+{
+  .hash : { *(.hash) }
+  .dynsym : { *(.dynsym) }
+  .dynstr : { *(.dynstr) }
+  .rel.dyn : { *(.rel.dyn) }
+  .text : { *(.text) }
+  .dynamic : { *(.dynamic) }
+  .data : { *(.data) }
+  .symtab : { *(.symtab) }
+  .strtab : { *(.strtab) }
+  .shstrtab : { *(.shstrtab) }
+  .plt : { *(.plt) }
+  .got.plt : { *(.got.plt) }
+  .got : { *(.got) }
+  /DISCARD/ : { *(*) }
+}
diff --git a/ld/testsuite/ld-elf/pr21233.s b/ld/testsuite/ld-elf/pr21233.s
new file mode 100644
index 0000000000..0c405c6dff
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr21233.s
@@ -0,0 +1,8 @@
+	.text
+	.globl	foo
+	.type	foo, %function
+foo:
+	.size	foo, . - foo
+
+	.data
+	.dc.a	bar
diff --git a/ld/testsuite/ld-elf/pr21233.sd b/ld/testsuite/ld-elf/pr21233.sd
new file mode 100644
index 0000000000..74d446d755
--- /dev/null
+++ b/ld/testsuite/ld-elf/pr21233.sd
@@ -0,0 +1,9 @@
+# Make sure the `bar' reference is global rather than local
+# in the dynamic symbol table, e.g.:
+#    Num:    Value  Size Type    Bind   Vis      Ndx Name
+#      1: 00000000     0 OBJECT  GLOBAL DEFAULT  UND bar
+# vs:
+#      1: 00000000     0 OBJECT  LOCAL  DEFAULT  UND bar
+#...
+ *[0-9]+: +[0-9a-f]+ +0 +OBJECT +GLOBAL +DEFAULT +UND +bar
+#pass
diff --git a/ld/testsuite/ld-elf/shared.exp b/ld/testsuite/ld-elf/shared.exp
index 300100a6c2..be30ec0235 100644
--- a/ld/testsuite/ld-elf/shared.exp
+++ b/ld/testsuite/ld-elf/shared.exp
@@ -115,6 +115,45 @@ if { [check_gc_sections_available] } {
 	    {{objdump -p pr20828-v.od}} \
 	    "pr20828-v-2"]]
 }
+# PR ld/21233 check for correct dynamic symbol table entries where:
+# - a symbol has been defined in a shared library used in the link,
+# - the symbol has been referenced from a section swept in garbage collection,
+# - the symbol has also been forced to be entered in the output file as an
+#   undefined symbol, either with a command-line option or a linker script
+#   command.
+# Verify that the undefined symbol is global rather than local.
+if { [check_gc_sections_available] } {
+    run_ld_link_tests [list \
+	[list \
+	    "PR ld/21233 dynamic symbols with section GC\
+	     (auxiliary shared library)" \
+	    "$LFLAGS -shared -T pr21233.ld" "" "$AFLAGS_PIC" \
+	    {pr21233-l.s} \
+	    {{readelf --dyn-syms pr21233-l.sd}} \
+	    "libpr21233.so"] \
+	[list \
+	    "PR ld/21233 dynamic symbols with section GC (--undefined)" \
+	    "$LFLAGS --gc-sections -e foo --undefined=bar -T pr21233.ld" \
+	    "tmpdir/libpr21233.so" "" \
+	    {pr21233.s} \
+	    {{readelf --dyn-syms pr21233.sd}} \
+	    "pr21233-1"] \
+	[list \
+	    "PR ld/21233 dynamic symbols with section GC (--require-defined)" \
+	    "$LFLAGS --gc-sections -e foo --require-defined=bar\
+	     -T pr21233.ld" \
+	    "tmpdir/libpr21233.so" "" \
+	    {pr21233.s} \
+	    {{readelf --dyn-syms pr21233.sd}} \
+	    "pr21233-2"] \
+	[list \
+	    "PR ld/21233 dynamic symbols with section GC (EXTERN)" \
+	    "$LFLAGS --gc-sections -e foo -T pr21233-e.ld" \
+	    "tmpdir/libpr21233.so" "" \
+	    {pr21233.s} \
+	    {{readelf --dyn-syms pr21233.sd}} \
+	    "pr21233-3"]]
+}
 
 # Check to see if the C compiler works
 if { [which $CC] == 0 } {