diff --git a/llvm/lib/Target/PowerPC/PPCInstrInfo.td b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
--- a/llvm/lib/Target/PowerPC/PPCInstrInfo.td
+++ b/llvm/lib/Target/PowerPC/PPCInstrInfo.td
@@ -4627,19 +4627,8 @@
 
 def : InstAlias<"mtasr $RS", (MTSPR 280, gprc:$RS)>;
 
-def : InstAlias<"mfdec $RT", (MFSPR gprc:$RT, 22)>;
-def : InstAlias<"mtdec $RT", (MTSPR 22, gprc:$RT)>;
-
 def : InstAlias<"mfpvr $RT", (MFSPR gprc:$RT, 287)>;
 
-def : InstAlias<"mfsdr1 $RT", (MFSPR gprc:$RT, 25)>;
-def : InstAlias<"mtsdr1 $RT", (MTSPR 25, gprc:$RT)>;
-
-def : InstAlias<"mfsrr0 $RT", (MFSPR gprc:$RT, 26)>;
-def : InstAlias<"mfsrr1 $RT", (MFSPR gprc:$RT, 27)>;
-def : InstAlias<"mtsrr0 $RT", (MTSPR 26, gprc:$RT)>;
-def : InstAlias<"mtsrr1 $RT", (MTSPR 27, gprc:$RT)>;
-
 def : InstAlias<"tlbie $RB", (TLBIE R0, gprc:$RB)>;
 
 def : InstAlias<"tlbrehi $RS, $A", (TLBRE2 gprc:$RS, gprc:$A, 0)>,
diff --git a/llvm/test/MC/Disassembler/PowerPC/ppc64-encoding-bookIII.txt b/llvm/test/MC/Disassembler/PowerPC/ppc64-encoding-bookIII.txt
--- a/llvm/test/MC/Disassembler/PowerPC/ppc64-encoding-bookIII.txt
+++ b/llvm/test/MC/Disassembler/PowerPC/ppc64-encoding-bookIII.txt
@@ -60,31 +60,31 @@
 # CHECK: mtspr 280, 4                    
 0x7c 0x98 0x43 0xa6
 
-# CHECK: mfspr 4, 22                     
+# CHECK: mfdec 4                         
 0x7c 0x96 0x02 0xa6
 
-# CHECK: mtspr 22, 4                     
+# CHECK: mtdec 4                         
 0x7c 0x96 0x03 0xa6
 
 # CHECK: mfpvr 4
 0x7c 0x9f 0x42 0xa6
 
-# CHECK: mfspr 4, 25                     
+# CHECK: mfsdr1 4                        
 0x7c 0x99 0x02 0xa6
 
-# CHECK: mtspr 25, 4                     
+# CHECK: mtsdr1 4                        
 0x7c 0x99 0x03 0xa6
 
-# CHECK: mfspr 4, 26                     
+# CHECK: mfsrr0 4                        
 0x7c 0x9a 0x02 0xa6
 
-# CHECK: mtspr 26, 4                     
+# CHECK: mtsrr0 4                        
 0x7c 0x9a 0x03 0xa6
 
-# CHECK: mfspr 4, 27                     
+# CHECK: mfsrr1 4                        
 0x7c 0x9b 0x02 0xa6
 
-# CHECK: mtspr 27, 4                     
+# CHECK: mtsrr1 4                        
 0x7c 0x9b 0x03 0xa6
 
 # CHECK: slbie 4                         
diff --git a/llvm/test/MC/PowerPC/ppc64-encoding-bookIII.s b/llvm/test/MC/PowerPC/ppc64-encoding-bookIII.s
--- a/llvm/test/MC/PowerPC/ppc64-encoding-bookIII.s
+++ b/llvm/test/MC/PowerPC/ppc64-encoding-bookIII.s
@@ -94,40 +94,40 @@
 # CHECK-LE: mtspr 280, 4                    # encoding: [0xa6,0x43,0x98,0x7c]
             mtasr %r4
 
-# CHECK-BE: mfspr 4, 22                     # encoding: [0x7c,0x96,0x02,0xa6]
-# CHECK-LE: mfspr 4, 22                     # encoding: [0xa6,0x02,0x96,0x7c]
+# CHECK-BE: mfdec 4                         # encoding: [0x7c,0x96,0x02,0xa6]
+# CHECK-LE: mfdec 4                         # encoding: [0xa6,0x02,0x96,0x7c]
             mfdec %r4
 
-# CHECK-BE: mtspr 22, 4                     # encoding: [0x7c,0x96,0x03,0xa6]
-# CHECK-LE: mtspr 22, 4                     # encoding: [0xa6,0x03,0x96,0x7c]
+# CHECK-BE: mtdec 4                         # encoding: [0x7c,0x96,0x03,0xa6]
+# CHECK-LE: mtdec 4                         # encoding: [0xa6,0x03,0x96,0x7c]
             mtdec %r4
 
 # CHECK-BE: mfpvr 4                         # encoding: [0x7c,0x9f,0x42,0xa6]
 # CHECK-LE: mfpvr 4                         # encoding: [0xa6,0x42,0x9f,0x7c]
             mfpvr %r4
 
-# CHECK-BE: mfspr 4, 25                     # encoding: [0x7c,0x99,0x02,0xa6]
-# CHECK-LE: mfspr 4, 25                     # encoding: [0xa6,0x02,0x99,0x7c]
+# CHECK-BE: mfsdr1 4                        # encoding: [0x7c,0x99,0x02,0xa6]
+# CHECK-LE: mfsdr1 4                        # encoding: [0xa6,0x02,0x99,0x7c]
             mfsdr1 %r4
 
-# CHECK-BE: mtspr 25, 4                     # encoding: [0x7c,0x99,0x03,0xa6]
-# CHECK-LE: mtspr 25, 4                     # encoding: [0xa6,0x03,0x99,0x7c]
+# CHECK-BE: mtsdr1 4                        # encoding: [0x7c,0x99,0x03,0xa6]
+# CHECK-LE: mtsdr1 4                        # encoding: [0xa6,0x03,0x99,0x7c]
             mtsdr1 %r4
 
-# CHECK-BE: mfspr 4, 26                     # encoding: [0x7c,0x9a,0x02,0xa6]
-# CHECK-LE: mfspr 4, 26                     # encoding: [0xa6,0x02,0x9a,0x7c]
+# CHECK-BE: mfsrr0 4                        # encoding: [0x7c,0x9a,0x02,0xa6]
+# CHECK-LE: mfsrr0 4                        # encoding: [0xa6,0x02,0x9a,0x7c]
             mfsrr0 %r4
 
-# CHECK-BE: mtspr 26, 4                     # encoding: [0x7c,0x9a,0x03,0xa6]
-# CHECK-LE: mtspr 26, 4                     # encoding: [0xa6,0x03,0x9a,0x7c]
+# CHECK-BE: mtsrr0 4                        # encoding: [0x7c,0x9a,0x03,0xa6]
+# CHECK-LE: mtsrr0 4                        # encoding: [0xa6,0x03,0x9a,0x7c]
             mtsrr0 %r4
 
-# CHECK-BE: mfspr 4, 27                     # encoding: [0x7c,0x9b,0x02,0xa6]
-# CHECK-LE: mfspr 4, 27                     # encoding: [0xa6,0x02,0x9b,0x7c]
+# CHECK-BE: mfsrr1 4                        # encoding: [0x7c,0x9b,0x02,0xa6]
+# CHECK-LE: mfsrr1 4                        # encoding: [0xa6,0x02,0x9b,0x7c]
             mfsrr1 %r4
 
-# CHECK-BE: mtspr 27, 4                     # encoding: [0x7c,0x9b,0x03,0xa6]
-# CHECK-LE: mtspr 27, 4                     # encoding: [0xa6,0x03,0x9b,0x7c]
+# CHECK-BE: mtsrr1 4                        # encoding: [0x7c,0x9b,0x03,0xa6]
+# CHECK-LE: mtsrr1 4                        # encoding: [0xa6,0x03,0x9b,0x7c]
             mtsrr1 %r4
 
 # CHECK-BE: slbie 4                         # encoding: [0x7c,0x00,0x23,0x64]
diff --git a/llvm/test/MC/PowerPC/ppc64-encoding-ext.s b/llvm/test/MC/PowerPC/ppc64-encoding-ext.s
--- a/llvm/test/MC/PowerPC/ppc64-encoding-ext.s
+++ b/llvm/test/MC/PowerPC/ppc64-encoding-ext.s
@@ -3443,29 +3443,29 @@
 # CHECK-BE: mfdar 2                         # encoding: [0x7c,0x53,0x02,0xa6]
 # CHECK-LE: mfdar 2                         # encoding: [0xa6,0x02,0x53,0x7c]
             mfdar 2
-# CHECK-BE: mtspr 22, 2                     # encoding: [0x7c,0x56,0x03,0xa6]
-# CHECK-LE: mtspr 22, 2                     # encoding: [0xa6,0x03,0x56,0x7c]
+# CHECK-BE: mtdec 2                         # encoding: [0x7c,0x56,0x03,0xa6]
+# CHECK-LE: mtdec 2                         # encoding: [0xa6,0x03,0x56,0x7c]
             mtdec 2
-# CHECK-BE: mfspr 2, 22                     # encoding: [0x7c,0x56,0x02,0xa6]
-# CHECK-LE: mfspr 2, 22                     # encoding: [0xa6,0x02,0x56,0x7c]
+# CHECK-BE: mfdec 2                         # encoding: [0x7c,0x56,0x02,0xa6]
+# CHECK-LE: mfdec 2                         # encoding: [0xa6,0x02,0x56,0x7c]
             mfdec 2
-# CHECK-BE: mtspr 25, 2                     # encoding: [0x7c,0x59,0x03,0xa6]
-# CHECK-LE: mtspr 25, 2                     # encoding: [0xa6,0x03,0x59,0x7c]
+# CHECK-BE: mtsdr1 2                        # encoding: [0x7c,0x59,0x03,0xa6]
+# CHECK-LE: mtsdr1 2                        # encoding: [0xa6,0x03,0x59,0x7c]
             mtsdr1 2
-# CHECK-BE: mfspr 2, 25                     # encoding: [0x7c,0x59,0x02,0xa6]
-# CHECK-LE: mfspr 2, 25                     # encoding: [0xa6,0x02,0x59,0x7c]
+# CHECK-BE: mfsdr1 2                        # encoding: [0x7c,0x59,0x02,0xa6]
+# CHECK-LE: mfsdr1 2                        # encoding: [0xa6,0x02,0x59,0x7c]
             mfsdr1 2
-# CHECK-BE: mtspr 26, 2                     # encoding: [0x7c,0x5a,0x03,0xa6]
-# CHECK-LE: mtspr 26, 2                     # encoding: [0xa6,0x03,0x5a,0x7c]
+# CHECK-BE: mtsrr0 2                        # encoding: [0x7c,0x5a,0x03,0xa6]
+# CHECK-LE: mtsrr0 2                        # encoding: [0xa6,0x03,0x5a,0x7c]
             mtsrr0 2
-# CHECK-BE: mfspr 2, 26                     # encoding: [0x7c,0x5a,0x02,0xa6]
-# CHECK-LE: mfspr 2, 26                     # encoding: [0xa6,0x02,0x5a,0x7c]
+# CHECK-BE: mfsrr0 2                        # encoding: [0x7c,0x5a,0x02,0xa6]
+# CHECK-LE: mfsrr0 2                        # encoding: [0xa6,0x02,0x5a,0x7c]
             mfsrr0 2
-# CHECK-BE: mtspr 27, 2                     # encoding: [0x7c,0x5b,0x03,0xa6]
-# CHECK-LE: mtspr 27, 2                     # encoding: [0xa6,0x03,0x5b,0x7c]
+# CHECK-BE: mtsrr1 2                        # encoding: [0x7c,0x5b,0x03,0xa6]
+# CHECK-LE: mtsrr1 2                        # encoding: [0xa6,0x03,0x5b,0x7c]
             mtsrr1 2
-# CHECK-BE: mfspr 2, 27                     # encoding: [0x7c,0x5b,0x02,0xa6]
-# CHECK-LE: mfspr 2, 27                     # encoding: [0xa6,0x02,0x5b,0x7c]
+# CHECK-BE: mfsrr1 2                        # encoding: [0x7c,0x5b,0x02,0xa6]
+# CHECK-LE: mfsrr1 2                        # encoding: [0xa6,0x02,0x5b,0x7c]
             mfsrr1 2
 # CHECK-BE: mtcfar 2                        # encoding: [0x7c,0x5c,0x03,0xa6]
 # CHECK-LE: mtcfar 2                        # encoding: [0xa6,0x03,0x5c,0x7c]