diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfo.td b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
--- a/llvm/lib/Target/RISCV/RISCVInstrInfo.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfo.td
@@ -332,6 +332,12 @@
                                    N->getValueType(0));
 }]>;
 
+// Return an immediate subtracted from 32.
+def ThirtyTwoMinusImm : SDNodeXForm<imm, [{
+  return CurDAG->getTargetConstant(32 - N->getZExtValue(), SDLoc(N),
+                                   N->getValueType(0));
+}]>;
+
 //===----------------------------------------------------------------------===//
 // Instruction Formats
 //===----------------------------------------------------------------------===//
@@ -855,6 +861,13 @@
   return MatchSRLIW(N);
 }]>;
 
+// Check that it is a SLLIUW (Shift Logical Left Immediate Unsigned i32
+// on RV64). Also used to optimize the same sequence without SLLIUW.
+def SLLIUWPat : PatFrag<(ops node:$A, node:$B),
+                        (and (shl node:$A, node:$B), imm), [{
+  return MatchSLLIUW(N);
+}]>;
+
 /// Immediates
 
 def : Pat<(simm12:$imm), (ADDI X0, simm12:$imm)>;
@@ -1158,9 +1171,18 @@
 
 /// RV64 patterns
 
-let Predicates = [IsRV64, NotHasStdExtZba] in
+let Predicates = [IsRV64, NotHasStdExtZba] in {
 def : Pat<(and GPR:$rs1, 0xffffffff), (SRLI (SLLI GPR:$rs1, 32), 32)>;
 
+// If we're shifting a 32-bit zero extended value left by 0-31 bits, use 2
+// shifts instead of 3. This can occur when unsigned is used to index an array.
+def : Pat<(shl (and GPR:$rs1, 0xffffffff), uimm5:$shamt),
+          (SRLI (SLLI GPR:$rs1, 32), (ThirtyTwoMinusImm uimm5:$shamt))>;
+// shl/and can appear in the other order too.
+def : Pat<(SLLIUWPat GPR:$rs1, uimm5:$shamt),
+          (SRLI (SLLI GPR:$rs1, 32), (ThirtyTwoMinusImm uimm5:$shamt))>;
+}
+
 let Predicates = [IsRV64] in {
 
 /// sext and zext
diff --git a/llvm/lib/Target/RISCV/RISCVInstrInfoB.td b/llvm/lib/Target/RISCV/RISCVInstrInfoB.td
--- a/llvm/lib/Target/RISCV/RISCVInstrInfoB.td
+++ b/llvm/lib/Target/RISCV/RISCVInstrInfoB.td
@@ -77,13 +77,6 @@
   return MatchSROIW(N);
 }]>;
 
-// Check that it is a SLLIUW (Shift Logical Left Immediate Unsigned i32
-// on RV64).
-def SLLIUWPat : PatFrag<(ops node:$A, node:$B),
-                        (and (shl node:$A, node:$B), imm), [{
-  return MatchSLLIUW(N);
-}]>;
-
 // Checks if this mask has a single 0 bit and cannot be used with ANDI.
 def BCLRMask : ImmLeaf<XLenVT, [{
   if (Subtarget->is64Bit())
diff --git a/llvm/test/CodeGen/RISCV/rv64Zba.ll b/llvm/test/CodeGen/RISCV/rv64Zba.ll
--- a/llvm/test/CodeGen/RISCV/rv64Zba.ll
+++ b/llvm/test/CodeGen/RISCV/rv64Zba.ll
@@ -9,11 +9,8 @@
 define i64 @slliuw(i64 %a) nounwind {
 ; RV64I-LABEL: slliuw:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 1
-; RV64I-NEXT:    addi a1, zero, 1
-; RV64I-NEXT:    slli a1, a1, 33
-; RV64I-NEXT:    addi a1, a1, -2
-; RV64I-NEXT:    and a0, a0, a1
+; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    srli a0, a0, 31
 ; RV64I-NEXT:    ret
 ;
 ; RV64IB-LABEL: slliuw:
@@ -34,8 +31,7 @@
 ; RV64I-LABEL: slliuw_2:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    slli a0, a0, 32
-; RV64I-NEXT:    srli a0, a0, 32
-; RV64I-NEXT:    slli a0, a0, 4
+; RV64I-NEXT:    srli a0, a0, 28
 ; RV64I-NEXT:    add a1, a1, a0
 ; RV64I-NEXT:    ld a0, 0(a1)
 ; RV64I-NEXT:    ld a1, 8(a1)
@@ -206,8 +202,7 @@
 ; RV64I-LABEL: sh1adduw:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    slli a0, a0, 32
-; RV64I-NEXT:    srli a0, a0, 32
-; RV64I-NEXT:    slli a0, a0, 1
+; RV64I-NEXT:    srli a0, a0, 31
 ; RV64I-NEXT:    add a0, a1, a0
 ; RV64I-NEXT:    lh a0, 0(a0)
 ; RV64I-NEXT:    ret
@@ -232,11 +227,8 @@
 define i64 @sh1adduw_2(i64 %0, i64 %1) {
 ; RV64I-LABEL: sh1adduw_2:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 1
-; RV64I-NEXT:    addi a2, zero, 1
-; RV64I-NEXT:    slli a2, a2, 33
-; RV64I-NEXT:    addi a2, a2, -2
-; RV64I-NEXT:    and a0, a0, a2
+; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    srli a0, a0, 31
 ; RV64I-NEXT:    add a0, a0, a1
 ; RV64I-NEXT:    ret
 ;
@@ -259,8 +251,7 @@
 ; RV64I-LABEL: sh2adduw:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    slli a0, a0, 32
-; RV64I-NEXT:    srli a0, a0, 32
-; RV64I-NEXT:    slli a0, a0, 2
+; RV64I-NEXT:    srli a0, a0, 30
 ; RV64I-NEXT:    add a0, a1, a0
 ; RV64I-NEXT:    lw a0, 0(a0)
 ; RV64I-NEXT:    ret
@@ -285,11 +276,8 @@
 define i64 @sh2adduw_2(i64 %0, i64 %1) {
 ; RV64I-LABEL: sh2adduw_2:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 2
-; RV64I-NEXT:    addi a2, zero, 1
-; RV64I-NEXT:    slli a2, a2, 34
-; RV64I-NEXT:    addi a2, a2, -4
-; RV64I-NEXT:    and a0, a0, a2
+; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    srli a0, a0, 30
 ; RV64I-NEXT:    add a0, a0, a1
 ; RV64I-NEXT:    ret
 ;
@@ -312,8 +300,7 @@
 ; RV64I-LABEL: sh3adduw:
 ; RV64I:       # %bb.0:
 ; RV64I-NEXT:    slli a0, a0, 32
-; RV64I-NEXT:    srli a0, a0, 32
-; RV64I-NEXT:    slli a0, a0, 3
+; RV64I-NEXT:    srli a0, a0, 29
 ; RV64I-NEXT:    add a0, a1, a0
 ; RV64I-NEXT:    ld a0, 0(a0)
 ; RV64I-NEXT:    ret
@@ -338,11 +325,8 @@
 define i64 @sh3adduw_2(i64 %0, i64 %1) {
 ; RV64I-LABEL: sh3adduw_2:
 ; RV64I:       # %bb.0:
-; RV64I-NEXT:    slli a0, a0, 3
-; RV64I-NEXT:    addi a2, zero, 1
-; RV64I-NEXT:    slli a2, a2, 35
-; RV64I-NEXT:    addi a2, a2, -8
-; RV64I-NEXT:    and a0, a0, a2
+; RV64I-NEXT:    slli a0, a0, 32
+; RV64I-NEXT:    srli a0, a0, 29
 ; RV64I-NEXT:    add a0, a0, a1
 ; RV64I-NEXT:    ret
 ;