Index: docs/LangRef.rst
===================================================================
--- docs/LangRef.rst
+++ docs/LangRef.rst
@@ -3814,6 +3814,8 @@
 - ``w``: A 32, 64, or 128-bit floating-point, SIMD or SVE vector register.
 - ``x``: Like w, but restricted to registers 0 to 15 inclusive.
 - ``y``: Like w, but restricted to SVE vector registers Z0 to Z7 inclusive.
+- ``Upl``: One of the low eight SVE predicate registers (P0 to P7)
+- ``Upa``: Any of the SVE predicate registers (P0 to P15)
 
 AMDGPU:
 
Index: lib/IR/InlineAsm.cpp
===================================================================
--- lib/IR/InlineAsm.cpp
+++ lib/IR/InlineAsm.cpp
@@ -181,6 +181,16 @@
       // FIXME: For now assuming these are 2-character constraints.
       pCodes->push_back(StringRef(I+1, 2));
       I += 3;
+    } else if (*I == '@') {
+      // Multi-letter constraint
+      ++I;
+      unsigned char C = static_cast<unsigned char>(*I);
+      assert(isdigit(C) && "Not a single digit!");
+      int N = C - '0';
+      assert(N > 0 && "Found a zero letter constraint!");
+      ++I;
+      pCodes->push_back(std::string(I, I+N));
+      I += N;
     } else {
       // Single letter constraint.
       pCodes->push_back(StringRef(I, 1));
Index: lib/Target/AArch64/AArch64AsmPrinter.cpp
===================================================================
--- lib/Target/AArch64/AArch64AsmPrinter.cpp
+++ lib/Target/AArch64/AArch64AsmPrinter.cpp
@@ -620,6 +620,9 @@
     if (AArch64::ZPRRegClass.contains(Reg)) {
       RegClass = &AArch64::ZPRRegClass;
       hasAltName = false;
+    } else if (AArch64::PPRRegClass.contains(Reg)) {
+      RegClass = &AArch64::PPRRegClass;
+      hasAltName = false;
     } else {
       RegClass = &AArch64::FPR128RegClass;
       hasAltName = true;
Index: lib/Target/AArch64/AArch64ISelLowering.cpp
===================================================================
--- lib/Target/AArch64/AArch64ISelLowering.cpp
+++ lib/Target/AArch64/AArch64ISelLowering.cpp
@@ -5764,6 +5764,10 @@
     case 'S': // A symbolic address
       return C_Other;
     }
+  } else if (Constraint.size() == 3 && Constraint[0] == 'U'
+               && Constraint[1] == 'p'
+               && (Constraint[2] == 'l' || Constraint[2] == 'a')) {
+      return C_RegisterClass;
   }
   return TargetLowering::getConstraintType(Constraint);
 }
@@ -5795,6 +5799,10 @@
   case 'z':
     weight = CW_Constant;
     break;
+  case 'U':
+    if (constraint[1] == 'p' && (constraint[2] == 'l' || constraint[2] == 'a'))
+      weight = CW_Register;
+    break;
   }
   return weight;
 }
@@ -5838,6 +5846,13 @@
         return std::make_pair(0U, &AArch64::ZPR_3bRegClass);
       break;
     }
+  } else if (Constraint.size() == 3 && Constraint[0] == 'U'
+             && Constraint[1] == 'p'
+             && (Constraint[2] == 'l' || Constraint[2] == 'a')) {
+    assert(VT.isScalableVector());
+    bool restricted = (Constraint[2] == 'l');
+    return restricted ? std::make_pair(0U, &AArch64::PPR_3bRegClass)
+                        : std::make_pair(0U, &AArch64::PPRRegClass);
   }
   if (StringRef("{cc}").equals_lower(Constraint))
     return std::make_pair(unsigned(AArch64::NZCV), &AArch64::CCRRegClass);
Index: lib/Target/AArch64/AArch64InstrInfo.cpp
===================================================================
--- lib/Target/AArch64/AArch64InstrInfo.cpp
+++ lib/Target/AArch64/AArch64InstrInfo.cpp
@@ -2486,6 +2486,17 @@
     return;
   }
 
+  // Copy a Predicate register by ORRing with itself.
+  if (AArch64::PPRRegClass.contains(DestReg) &&
+      AArch64::PPRRegClass.contains(SrcReg)) {
+    assert(Subtarget.hasSVE() && "Unexpected SVE register.");
+    BuildMI(MBB, I, DL, get(AArch64::ORR_PPzPP), DestReg)
+      .addReg(SrcReg) // Pg
+      .addReg(SrcReg)
+      .addReg(SrcReg, getKillRegState(KillSrc));
+    return;
+  }
+
   // Copy a Z register by ORRing with itself.
   if (AArch64::ZPRRegClass.contains(DestReg) &&
       AArch64::ZPRRegClass.contains(SrcReg)) {
Index: test/CodeGen/AArch64/aarch64-sve-asm.ll
===================================================================
--- test/CodeGen/AArch64/aarch64-sve-asm.ll
+++ test/CodeGen/AArch64/aarch64-sve-asm.ll
@@ -43,4 +43,24 @@
   ret <vscale x 4 x float> %1
 }
 
+; Function Attrs: nounwind readnone
+; CHECK: [[ARG1:%[0-9]+]]:zpr = COPY $z1
+; CHECK: [[ARG2:%[0-9]+]]:zpr = COPY $z0
+; CHECK: [[ARG3:%[0-9]+]]:ppr = COPY $p0
+; CHECK: [[ARG4:%[0-9]+]]:ppr_3b = COPY [[ARG3]]
+define <vscale x 8 x half> @test_svfadd_f16(<vscale x 16 x i1> %Pg, <vscale x 8 x half> %Zn, <vscale x 8 x half> %Zm) {
+  %1 = tail call <vscale x 8 x half> asm "fadd $0.h, $1/m, $2.h, $3.h", "=w,@3Upl,w,w"(<vscale x 16 x i1> %Pg, <vscale x 8 x half> %Zn, <vscale x 8 x half> %Zm)
+  ret <vscale x 8 x half> %1
+}
+
+; Function Attrs: nounwind readnone
+; CHECK: [[ARG1:%[0-9]+]]:zpr = COPY $z0
+; CHECK: [[ARG2:%[0-9]+]]:ppr = COPY $p0
+; CHECK: [[ARG3:%[0-9]+]]:ppr = COPY [[ARG2]]
+; CHECK: [[ARG4:%[0-9]+]]:zpr = COPY [[ARG1]]
+define <vscale x 4 x i32> @test_incp(<vscale x 16 x i1> %Pg, <vscale x 4 x i32> %Zn) {
+  %1 = tail call <vscale x 4 x i32> asm "incp $0.s, $1", "=w,@3Upa,0"(<vscale x 16 x i1> %Pg, <vscale x 4 x i32> %Zn)
+  ret <vscale x 4 x i32> %1
+}
+
 !0 = !{i32 188, i32 210}