Index: lib/CodeGen/CGBuiltin.cpp
===================================================================
--- lib/CodeGen/CGBuiltin.cpp
+++ lib/CodeGen/CGBuiltin.cpp
@@ -238,10 +238,19 @@
   llvm::Type *IntTy = llvm::IntegerType::get(C, Width);
   V = CGF.Builder.CreateBitCast(V, IntTy);
   if (Ty->isPPC_FP128Ty()) {
-    // The higher-order double comes first, and so we need to truncate the
-    // pair to extract the overall sign. The order of the pair is the same
-    // in both little- and big-Endian modes.
+    // Bitcast works as if ppcf128 is stored to memory, and then read as i128.
+    // The higher-order double in ppcf128 comes first in both little- and 
+    // big-Endian modes.
+    // On big-Endian, high-double will be in high part of i128.
+    // On little-Endian, high-double will be in low part of i128.
+    // Therefore, on big-Endian we shift high part to low part.
     Width >>= 1;
+    if (CGF.getTarget().isBigEndian()) {
+      Value *ShiftCst = llvm::ConstantInt::get(IntTy, Width);
+      V = CGF.Builder.CreateLShr(V, ShiftCst);
+    } 
+    // After we have high-dobule in the low part of i128
+    // we need to truncate it to extract the sign.
     IntTy = llvm::IntegerType::get(C, Width);
     V = CGF.Builder.CreateTrunc(V, IntTy);
   }
Index: test/Analysis/builtin_signbit.cpp
===================================================================
--- test/Analysis/builtin_signbit.cpp
+++ test/Analysis/builtin_signbit.cpp
@@ -0,0 +1,43 @@
+// RUN: %clang -target powerpc-linux-gnu     -emit-llvm -S -O0 %s -o - | FileCheck %s --check-prefix=CHECK-BE --check-prefix=CHECK
+// RUN: %clang -target powerpc64-linux-gnu   -emit-llvm -S -O0 %s -o - | FileCheck %s --check-prefix=CHECK-BE --check-prefix=CHECK
+// RUN: %clang -target powerpc64le-linux-gnu -emit-llvm -S -O0 %s -o - | FileCheck %s --check-prefix=CHECK-LE --check-prefix=CHECK
+
+bool b;
+double d = -1.0;
+long double ld = -1.0L;
+void test_signbit()
+{
+  b = __builtin_signbit(1.0L);
+  // CHECK: i128
+  // CHECK-LE-NOT: lshr
+  // CHECK-BE: lshr
+  // CHECK: bitcast
+  // CHECK: ppc_fp128
+
+  b = __builtin_signbit(ld);
+  // CHECK: bitcast
+  // CHECK: ppc_fp128
+  // CHECK-LE-NOT: lshr
+  // CHECK-BE: lshr
+
+  b = __builtin_signbitf(1.0);
+  // CHECK: store i8 0
+
+  b = __builtin_signbitf(d);
+  // CHECK: bitcast
+  // CHECK-LE-NOT: lshr
+  // CHECK-BE-NOT: lshr
+
+  b = __builtin_signbitl(1.0L);
+  // CHECK: i128
+  // CHECK-LE-NOT: lshr
+  // CHECK-BE: lshr
+  // CHECK: bitcast
+  // CHECK: ppc_fp128
+
+  b = __builtin_signbitl(ld);
+  // CHECK: bitcast
+  // CHECK: ppc_fp128
+  // CHECK-LE-NOT: lshr
+  // CHECK-BE: lshr
+}