diff --git a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
--- a/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
+++ b/llvm/lib/CodeGen/SelectionDAG/DAGCombiner.cpp
@@ -562,6 +562,7 @@
     SDValue TransformFPLoadStorePair(SDNode *N);
     SDValue convertBuildVecZextToZext(SDNode *N);
     SDValue reduceBuildVecExtToExtBuildVec(SDNode *N);
+    SDValue reduceBuildVecTruncToBitCast(SDNode *N);
     SDValue reduceBuildVecToShuffle(SDNode *N);
     SDValue createBuildVecShuffle(const SDLoc &DL, SDNode *N,
                                   ArrayRef<int> VectorMask, SDValue VecIn1,
@@ -17474,6 +17475,84 @@
   return DAG.getBitcast(VT, BV);
 }
 
+// Simplify (build_vec (trunc $1)
+//                     (trunc (srl $1 half-width))
+//                     (trunc (srl $1 (2 * half-width))) …)
+// to (bitcast $1)
+SDValue DAGCombiner::reduceBuildVecTruncToBitCast(SDNode *N) {
+  assert(N->getOpcode() == ISD::BUILD_VECTOR && "Expected build vector");
+
+  // Only for little endian
+  if (!DAG.getDataLayout().isLittleEndian())
+    return SDValue();
+
+  SDLoc DL(N);
+  EVT VT = N->getValueType(0);
+  EVT OutScalarTy = VT.getScalarType();
+  uint64_t ScalarTypeBitsize = OutScalarTy.getSizeInBits();
+
+  // Only for power of two types to be sure that bitcast works well
+  if (!isPowerOf2_64(ScalarTypeBitsize))
+    return SDValue();
+
+  unsigned NumInScalars = N->getNumOperands();
+
+  // Look through bitcasts
+  auto PeekThroughBitcast = [](SDValue Op) {
+    if (Op.getOpcode() == ISD::BITCAST)
+      return Op.getOperand(0);
+    return Op;
+  };
+
+  // The source value where all the parts are extracted.
+  SDValue Src;
+  for (unsigned i = 0; i != NumInScalars; ++i) {
+    SDValue In = PeekThroughBitcast(N->getOperand(i));
+    // Ignore undef inputs.
+    if (In.isUndef()) continue;
+
+    if (In.getOpcode() != ISD::TRUNCATE)
+      return SDValue();
+
+    In = PeekThroughBitcast(In.getOperand(0));
+
+    if (In.getOpcode() != ISD::SRL) {
+      // For now only build_vec without shuffling, handle shifts here in the
+      // future.
+      if (i != 0)
+        return SDValue();
+
+      Src = In;
+    } else {
+      // In is SRL
+      SDValue part = PeekThroughBitcast(In.getOperand(0));
+
+      if (!Src) {
+        Src = part;
+      } else if (Src != part) {
+        // Vector parts do not stem from the same variable
+        return SDValue();
+      }
+
+      SDValue ShiftAmtVal = In.getOperand(1);
+      if (!isa<ConstantSDNode>(ShiftAmtVal))
+        return SDValue();
+
+      uint64_t ShiftAmt = In.getNode()->getConstantOperandVal(1);
+
+      // The extracted value is not extracted at the right position
+      if (ShiftAmt != i * ScalarTypeBitsize)
+        return SDValue();
+    }
+  }
+
+  // Only cast if the size is the same
+  if (Src.getValueType().getSizeInBits() != VT.getSizeInBits())
+    return SDValue();
+
+  return DAG.getBitcast(VT, Src);
+}
+
 SDValue DAGCombiner::createBuildVecShuffle(const SDLoc &DL, SDNode *N,
                                            ArrayRef<int> VectorMask,
                                            SDValue VecIn1, SDValue VecIn2,
@@ -18005,6 +18084,9 @@
   if (SDValue V = reduceBuildVecExtToExtBuildVec(N))
     return V;
 
+  if (SDValue V = reduceBuildVecTruncToBitCast(N))
+    return V;
+
   if (SDValue V = reduceBuildVecToShuffle(N))
     return V;
 
diff --git a/llvm/test/CodeGen/AMDGPU/scalar_to_vector.ll b/llvm/test/CodeGen/AMDGPU/scalar_to_vector.ll
--- a/llvm/test/CodeGen/AMDGPU/scalar_to_vector.ll
+++ b/llvm/test/CodeGen/AMDGPU/scalar_to_vector.ll
@@ -230,10 +230,9 @@
 ; SI-NEXT:    s_load_dword s2, s[0:1], 0xb
 ; SI-NEXT:    s_load_dwordx2 s[4:5], s[0:1], 0x9
 ; SI-NEXT:    s_mov_b32 s7, 0xf000
-; SI-NEXT:    s_waitcnt lgkmcnt(0)
-; SI-NEXT:    s_and_b32 s0, s2, 0xff
 ; SI-NEXT:    s_mov_b32 s6, -1
-; SI-NEXT:    v_mov_b32_e32 v0, s0
+; SI-NEXT:    s_waitcnt lgkmcnt(0)
+; SI-NEXT:    v_mov_b32_e32 v0, s2
 ; SI-NEXT:    buffer_store_dword v0, off, s[4:7], 0
 ; SI-NEXT:    s_endpgm
 ;
@@ -244,7 +243,6 @@
 ; VI-NEXT:    s_mov_b32 s7, 0xf000
 ; VI-NEXT:    s_mov_b32 s6, -1
 ; VI-NEXT:    s_waitcnt lgkmcnt(0)
-; VI-NEXT:    s_and_b32 s0, s0, 0xff
 ; VI-NEXT:    v_mov_b32_e32 v0, s0
 ; VI-NEXT:    buffer_store_dword v0, off, s[4:7], 0
 ; VI-NEXT:    s_endpgm
diff --git a/llvm/test/CodeGen/AMDGPU/vector_shuffle.packed.ll b/llvm/test/CodeGen/AMDGPU/vector_shuffle.packed.ll
--- a/llvm/test/CodeGen/AMDGPU/vector_shuffle.packed.ll
+++ b/llvm/test/CodeGen/AMDGPU/vector_shuffle.packed.ll
@@ -47,12 +47,9 @@
 ; GFX9-LABEL: shuffle_v4f16_u3u1:
 ; GFX9:       ; %bb.0:
 ; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX9-NEXT:    global_load_dwordx2 v[0:1], v[0:1], off
+; GFX9-NEXT:    global_load_dwordx2 v[1:2], v[0:1], off
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
-; GFX9-NEXT:    v_lshrrev_b32_e32 v1, 16, v1
-; GFX9-NEXT:    v_lshrrev_b32_e32 v2, 16, v0
-; GFX9-NEXT:    v_lshlrev_b32_e32 v0, 16, v1
-; GFX9-NEXT:    v_lshlrev_b32_e32 v1, 16, v2
+; GFX9-NEXT:    v_mov_b32_e32 v0, v2
 ; GFX9-NEXT:    s_setpc_b64 s[30:31]
   %val0 = load <4 x half>, <4 x half> addrspace(1)* %arg0
   %val1 = load <4 x half>, <4 x half> addrspace(1)* %arg1
@@ -66,8 +63,6 @@
 ; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
 ; GFX9-NEXT:    global_load_dword v0, v[0:1], off offset:4
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
-; GFX9-NEXT:    v_lshrrev_b32_e32 v0, 16, v0
-; GFX9-NEXT:    v_lshlrev_b32_e32 v0, 16, v0
 ; GFX9-NEXT:    s_setpc_b64 s[30:31]
   %val0 = load <4 x half>, <4 x half> addrspace(1)* %arg0
   %val1 = load <4 x half>, <4 x half> addrspace(1)* %arg1
@@ -95,13 +90,11 @@
 ; GFX9-LABEL: shuffle_v4f16_3uu7:
 ; GFX9:       ; %bb.0:
 ; GFX9-NEXT:    s_waitcnt vmcnt(0) expcnt(0) lgkmcnt(0)
-; GFX9-NEXT:    global_load_dword v2, v[2:3], off offset:4
 ; GFX9-NEXT:    global_load_dword v0, v[0:1], off offset:4
+; GFX9-NEXT:    global_load_dword v1, v[2:3], off offset:4
 ; GFX9-NEXT:    s_waitcnt vmcnt(1)
-; GFX9-NEXT:    v_lshrrev_b32_e32 v1, 16, v2
-; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    v_lshrrev_b32_e32 v0, 16, v0
-; GFX9-NEXT:    v_lshlrev_b32_e32 v1, 16, v1
+; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    s_setpc_b64 s[30:31]
   %val0 = load <4 x half>, <4 x half> addrspace(1)* %arg0
   %val1 = load <4 x half>, <4 x half> addrspace(1)* %arg1
@@ -117,11 +110,11 @@
 ; GFX9-NEXT:    global_load_dword v0, v[0:1], off offset:4
 ; GFX9-NEXT:    v_mov_b32_e32 v1, 0xffff
 ; GFX9-NEXT:    s_waitcnt vmcnt(1)
-; GFX9-NEXT:    v_lshrrev_b32_e32 v2, 16, v2
+; GFX9-NEXT:    v_lshrrev_b32_e32 v3, 16, v2
 ; GFX9-NEXT:    s_waitcnt vmcnt(0)
 ; GFX9-NEXT:    v_and_b32_sdwa v0, v1, v0 dst_sel:DWORD dst_unused:UNUSED_PAD src0_sel:DWORD src1_sel:WORD_1
-; GFX9-NEXT:    v_lshl_or_b32 v0, v2, 16, v0
-; GFX9-NEXT:    v_lshlrev_b32_e32 v1, 16, v2
+; GFX9-NEXT:    v_lshl_or_b32 v0, v3, 16, v0
+; GFX9-NEXT:    v_mov_b32_e32 v1, v2
 ; GFX9-NEXT:    s_setpc_b64 s[30:31]
   %val0 = load <4 x half>, <4 x half> addrspace(1)* %arg0
   %val1 = load <4 x half>, <4 x half> addrspace(1)* %arg1