diff --git a/gas/ChangeLog b/gas/ChangeLog
index 94c3bbb4cdd..122d27fc41c 100644
--- a/gas/ChangeLog
+++ b/gas/ChangeLog
@@ -1,3 +1,8 @@
+2020-09-09  Alan Modra  <amodra@gmail.com>
+
+	* config/tc-ppc.c (md_assemble): Emit prefix insn by parts when
+	valueT is smaller than 64 bits.
+
 2020-09-07  Cooper Qu  <cooper.qu@linux.alibaba.com>
 
 	* config/tc-csky.c (CSKYV2_ISA_DSP): CSKY_ISA_DSPE60.
diff --git a/gas/config/tc-ppc.c b/gas/config/tc-ppc.c
index 1ff1cd9eab2..441818215e1 100644
--- a/gas/config/tc-ppc.c
+++ b/gas/config/tc-ppc.c
@@ -3882,7 +3882,8 @@ md_assemble (char *str)
 
   /* The prefix part of an 8-byte instruction always occupies the lower
      addressed word in a doubleword, regardless of endianness.  */
-  if (!target_big_endian && insn_length == 8)
+  if (insn_length == 8
+      && (sizeof (insn) > sizeof (valueT) || !target_big_endian))
     {
       md_number_to_chars (f, PPC_GET_PREFIX (insn), 4);
       md_number_to_chars (f + 4, PPC_GET_SUFFIX (insn), 4);