diff --git a/clang/lib/Basic/Targets/PPC.h b/clang/lib/Basic/Targets/PPC.h
--- a/clang/lib/Basic/Targets/PPC.h
+++ b/clang/lib/Basic/Targets/PPC.h
@@ -207,7 +207,8 @@
       switch (Name[1]) {
       case 'd': // VSX vector register to hold vector double data
       case 'f': // VSX vector register to hold vector float data
-      case 's': // VSX vector register to hold scalar float data
+      case 's': // VSX vector register to hold scalar double data
+      case 'w': // VSX vector register to hold scalar double data
       case 'a': // Any VSX register
       case 'c': // An individual CR bit
       case 'i': // FP or VSX register to hold 64-bit integers data
diff --git a/clang/test/CodeGen/ppc64-inline-asm.c b/clang/test/CodeGen/ppc64-inline-asm.c
--- a/clang/test/CodeGen/ppc64-inline-asm.c
+++ b/clang/test/CodeGen/ppc64-inline-asm.c
@@ -24,3 +24,16 @@
 // CHECK: call i8 asm "crand $0, $1, $2", "=^wc,^wc,^wc"(i8 %b1, i8 %b2)
 }
 
+float test_fmaxf(float x, float y) {
+  asm("xsmaxdp %x0, %x1, %x2" : "=ww"(x) : "ww"(x), "ww"(y));
+  return x;
+// CHECK-LABEL: float @test_fmaxf(float %x, float %y)
+// CHECK: call float asm "xsmaxdp ${0:x}, ${1:x}, ${2:x}", "=^ww,^ww,^ww"(float %x, float %y)
+}
+
+double test_fmax(double x, double y) {
+  asm("xsmaxdp %x0, %x1, %x2" : "=ws"(x) : "ws"(x), "ws"(y));
+  return x;
+// CHECK-LABEL: double @test_fmax(double %x, double %y)
+// CHECK: call double asm "xsmaxdp ${0:x}, ${1:x}, ${2:x}", "=^ws,^ws,^ws"(double %x, double %y)
+}
diff --git a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
--- a/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
+++ b/llvm/lib/Target/PowerPC/PPCISelLowering.cpp
@@ -13958,7 +13958,7 @@
     return C_RegisterClass;
   } else if (Constraint == "wa" || Constraint == "wd" ||
              Constraint == "wf" || Constraint == "ws" ||
-             Constraint == "wi") {
+             Constraint == "wi" || Constraint == "ww") {
     return C_RegisterClass; // VSX registers.
   }
   return TargetLowering::getConstraintType(Constraint);
@@ -13986,10 +13986,12 @@
             StringRef(constraint) == "wf") &&
            type->isVectorTy())
     return CW_Register;
-  else if (StringRef(constraint) == "ws" && type->isDoubleTy())
-    return CW_Register;
   else if (StringRef(constraint) == "wi" && type->isIntegerTy(64))
     return CW_Register; // just hold 64-bit integers data.
+  else if (StringRef(constraint) == "ws" && type->isDoubleTy())
+    return CW_Register;
+  else if (StringRef(constraint) == "ww" && type->isFloatTy())
+    return CW_Register;
 
   switch (*constraint) {
   default:
@@ -14075,7 +14077,7 @@
              Constraint == "wf" || Constraint == "wi") &&
              Subtarget.hasVSX()) {
     return std::make_pair(0U, &PPC::VSRCRegClass);
-  } else if (Constraint == "ws" && Subtarget.hasVSX()) {
+  } else if ((Constraint == "ws" || Constraint == "ww") && Subtarget.hasVSX()) {
     if (VT == MVT::f32 && Subtarget.hasP8Vector())
       return std::make_pair(0U, &PPC::VSSRCRegClass);
     else
diff --git a/llvm/test/CodeGen/PowerPC/inlineasm-vsx-reg.ll b/llvm/test/CodeGen/PowerPC/inlineasm-vsx-reg.ll
--- a/llvm/test/CodeGen/PowerPC/inlineasm-vsx-reg.ll
+++ b/llvm/test/CodeGen/PowerPC/inlineasm-vsx-reg.ll
@@ -38,3 +38,12 @@
 ; CHECK: mtvsrd v2, r1
 ; CHECK: #NO_APP
 }
+
+define float @test_ww(float %x, float %y) {
+  %1 = tail call float asm "xsmaxdp ${0:x}, ${1:x}, ${2:x}", "=^ww,^ww,^ww"(float %x, float %y)
+  ret float %1
+; CHECK-LABEL: test_ww:
+; CHECK: #APP
+; CHECK: xsmaxdp f1, f1, f2
+; CHECK: #NO_APP
+}
diff --git a/llvm/test/CodeGen/PowerPC/vec-asm-disabled.ll b/llvm/test/CodeGen/PowerPC/vec-asm-disabled.ll
--- a/llvm/test/CodeGen/PowerPC/vec-asm-disabled.ll
+++ b/llvm/test/CodeGen/PowerPC/vec-asm-disabled.ll
@@ -19,5 +19,17 @@
 ; CHECK: error: couldn't allocate output register for constraint 'wi'
 }
 
+define float @test_ww(float %x, float %y) #0 {
+  %1 = tail call float asm "xsmaxdp ${0:x},${1:x},${2:x}", "=^ww,^ww,^ww"(float %x, float %y) #0
+  ret float %1
+; CHECK: error: couldn't allocate output register for constraint 'ww'
+}
+
+define double @test_ws(double %x, double %y) #0 {
+  %1 = tail call double asm "xsmaxdp ${0:x},${1:x},${2:x}", "=^ws,^ws,^ws"(double %x, double %y) #0
+  ret double %1
+; CHECK: error: couldn't allocate output register for constraint 'ws'
+}
+
 attributes #0 = { nounwind "target-features"="-vsx" }