diff --git a/gcc/ChangeLog b/gcc/ChangeLog
index 8de7e8cf188..d170efe04c1 100644
--- a/gcc/ChangeLog
+++ b/gcc/ChangeLog
@@ -1,3 +1,11 @@
+2018-01-16  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	Backport from mainline
+	2017-12-18  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/83424
+	* rtlanal.c (dead_or_set_regno_p): Handle CLOBBER just like SET.
+
 2018-01-16  H.J. Lu  <hongjiu.lu@intel.com>
 
 	* config/i386/i386.c (ix86_expand_prologue): Don't use reference
diff --git a/gcc/rtlanal.c b/gcc/rtlanal.c
index b93d19537bb..8e85f14525d 100644
--- a/gcc/rtlanal.c
+++ b/gcc/rtlanal.c
@@ -2050,7 +2050,7 @@ dead_or_set_regno_p (const rtx_insn *insn, unsigned int test_regno)
   if (GET_CODE (pattern) == COND_EXEC)
     return 0;
 
-  if (GET_CODE (pattern) == SET)
+  if (GET_CODE (pattern) == SET || GET_CODE (pattern) == CLOBBER)
     return covers_regno_p (SET_DEST (pattern), test_regno);
   else if (GET_CODE (pattern) == PARALLEL)
     {
diff --git a/gcc/testsuite/ChangeLog b/gcc/testsuite/ChangeLog
index 6752d761d84..44e046eec5e 100644
--- a/gcc/testsuite/ChangeLog
+++ b/gcc/testsuite/ChangeLog
@@ -1,3 +1,11 @@
+2018-01-16  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	Backport from mainline
+	2017-12-18  Segher Boessenkool  <segher@kernel.crashing.org>
+
+	PR rtl-optimization/83424
+	* gcc.dg/pr83424.c: New testsuite.
+
 2018-01-16  H.J. Lu  <hongjiu.lu@intel.com>
 
 	Backport from mainline
diff --git a/gcc/testsuite/gcc.dg/pr83424.c b/gcc/testsuite/gcc.dg/pr83424.c
new file mode 100644
index 00000000000..5a304f50292
--- /dev/null
+++ b/gcc/testsuite/gcc.dg/pr83424.c
@@ -0,0 +1,30 @@
+/* PR rtl-optimization/83424 */
+/* { dg-do run { target int128 } } */
+/* { dg-options "-O -fno-tree-ccp -fno-tree-coalesce-vars" } */
+
+typedef unsigned char u8;
+typedef unsigned int u32;
+typedef unsigned __int128 u128;
+
+u32 a, c;
+u8 b;
+
+static u128 __attribute__ ((noinline, noclone))
+foo (u128 p)
+{
+  u8 x = ~b;
+  p &= c;
+  x *= -p;
+  x &= a == 0;
+  x >>= 1;
+  return p + x;
+}
+
+int
+main (void)
+{
+  u128 x = foo (0);
+  if (x != 0)
+    __builtin_abort ();
+  return 0;
+}