diff --git a/llvm/lib/Support/APFloat.cpp b/llvm/lib/Support/APFloat.cpp
--- a/llvm/lib/Support/APFloat.cpp
+++ b/llvm/lib/Support/APFloat.cpp
@@ -92,7 +92,7 @@
      Note: we need to make the value different from semBogus as otherwise
      an unsafe optimization may collapse both values to a single address,
      and we heavily rely on them having distinct addresses.             */
-  static const fltSemantics semPPCDoubleDouble = {-1, 0, 0, 0};
+  static const fltSemantics semPPCDoubleDouble = {-1, 0, 0, 128};
 
   /* These are legacy semantics for the fallback, inaccrurate implementation of
      IBM double-double, if the accurate semPPCDoubleDouble doesn't handle the
diff --git a/llvm/test/Transforms/InstCombine/bitcast-store.ll b/llvm/test/Transforms/InstCombine/bitcast-store.ll
--- a/llvm/test/Transforms/InstCombine/bitcast-store.ll
+++ b/llvm/test/Transforms/InstCombine/bitcast-store.ll
@@ -47,6 +47,16 @@
   ret void
 }
 
+; CHECK-LABEL: @ppcf128_ones_store
+; CHECK: store ppc_fp128 0xMFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFFF, ppc_fp128* %dest, align 16
+define void @ppcf128_ones_store(ppc_fp128* %dest) {
+entry:
+  %int = or i128 0, 340282366920938463463374607431768211455 ; 128 ones
+  %val = bitcast i128 %int to ppc_fp128
+  store ppc_fp128 %val, ppc_fp128* %dest, align 16
+  ret void
+}
+
 !0 = !{!1}
 !1 = !{!1, !2}
 !2 = !{!2}