diff --git a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.cpp b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.cpp
--- a/llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.cpp
+++ b/llvm/lib/Target/RISCV/MCTargetDesc/RISCVBaseInfo.cpp
@@ -62,15 +62,11 @@
   if (TargetABI != ABI_Unknown)
     return TargetABI;
 
-  // For now, default to the ilp32/ilp32e/lp64 ABI if no explicit ABI is given
-  // or an invalid/unrecognised string is given. In the future, it might be
-  // worth changing this to default to ilp32f/lp64f and ilp32d/lp64d when
-  // hardware support for floating point is present.
-  if (IsRV32E)
-    return ABI_ILP32E;
-  if (IsRV64)
-    return ABI_LP64;
-  return ABI_ILP32;
+  // If no explicit ABI is given, try to compute the default ABI.
+  auto ISAInfo = RISCVFeatures::parseFeatureBits(IsRV64, FeatureBits);
+  if (!ISAInfo)
+    report_fatal_error(ISAInfo.takeError());
+  return getTargetABI((*ISAInfo)->computeDefaultABI());
 }
 
 ABI getTargetABI(StringRef ABIName) {
diff --git a/llvm/test/CodeGen/RISCV/callee-saved-fpr64s.ll b/llvm/test/CodeGen/RISCV/callee-saved-fpr64s.ll
--- a/llvm/test/CodeGen/RISCV/callee-saved-fpr64s.ll
+++ b/llvm/test/CodeGen/RISCV/callee-saved-fpr64s.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=ILP32
-; RUN: llc -mtriple=riscv64 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+d -target-abi=lp64 -verify-machineinstrs< %s \
 ; RUN:   | FileCheck %s -check-prefix=LP64
 ; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi ilp32d -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=ILP32D
diff --git a/llvm/test/CodeGen/RISCV/double-bitmanip-dagcombines.ll b/llvm/test/CodeGen/RISCV/double-bitmanip-dagcombines.ll
--- a/llvm/test/CodeGen/RISCV/double-bitmanip-dagcombines.ll
+++ b/llvm/test/CodeGen/RISCV/double-bitmanip-dagcombines.ll
@@ -1,11 +1,11 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32I %s
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -target-abi=ilp32 -mattr=+d -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IFD %s
-; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64I %s
-; RUN: llc -mtriple=riscv64 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -target-abi=lp64 -mattr=+d -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64IFD %s
 ;
 ; This file tests cases where simple floating point operations can be
diff --git a/llvm/test/CodeGen/RISCV/double-calling-conv.ll b/llvm/test/CodeGen/RISCV/double-calling-conv.ll
--- a/llvm/test/CodeGen/RISCV/double-calling-conv.ll
+++ b/llvm/test/CodeGen/RISCV/double-calling-conv.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IFD %s
 
 ; Basic correctness checks for calling convention lowering for RV32D. This can
diff --git a/llvm/test/CodeGen/RISCV/double-previous-failure.ll b/llvm/test/CodeGen/RISCV/double-previous-failure.ll
--- a/llvm/test/CodeGen/RISCV/double-previous-failure.ll
+++ b/llvm/test/CodeGen/RISCV/double-previous-failure.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IFD %s
 
 define double @test(double %a) nounwind {
diff --git a/llvm/test/CodeGen/RISCV/double-stack-spill-restore.ll b/llvm/test/CodeGen/RISCV/double-stack-spill-restore.ll
--- a/llvm/test/CodeGen/RISCV/double-stack-spill-restore.ll
+++ b/llvm/test/CodeGen/RISCV/double-stack-spill-restore.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IFD %s
-; RUN: llc -mtriple=riscv64 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+d -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64IFD %s
 
 define double @func(double %d, i32 %n) nounwind {
diff --git a/llvm/test/CodeGen/RISCV/fastcc-float.ll b/llvm/test/CodeGen/RISCV/fastcc-float.ll
--- a/llvm/test/CodeGen/RISCV/fastcc-float.ll
+++ b/llvm/test/CodeGen/RISCV/fastcc-float.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+f,+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+f,+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:     | FileCheck %s
 
 define fastcc float @callee(<32 x float> %A) nounwind {
diff --git a/llvm/test/CodeGen/RISCV/float-bit-preserving-dagcombines.ll b/llvm/test/CodeGen/RISCV/float-bit-preserving-dagcombines.ll
--- a/llvm/test/CodeGen/RISCV/float-bit-preserving-dagcombines.ll
+++ b/llvm/test/CodeGen/RISCV/float-bit-preserving-dagcombines.ll
@@ -1,11 +1,11 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+f -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+f -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32F %s
-; RUN: llc -mtriple=riscv32 -mattr=+f,+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+f,+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32FD %s
-; RUN: llc -mtriple=riscv64 -mattr=+f -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+f -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64F %s
-; RUN: llc -mtriple=riscv64 -mattr=+f,+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+f,+d -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64FD %s
 
 ; These functions perform extra work to ensure that `%a3` starts in a
diff --git a/llvm/test/CodeGen/RISCV/inline-asm-clobbers.ll b/llvm/test/CodeGen/RISCV/inline-asm-clobbers.ll
--- a/llvm/test/CodeGen/RISCV/inline-asm-clobbers.ll
+++ b/llvm/test/CodeGen/RISCV/inline-asm-clobbers.ll
@@ -1,14 +1,14 @@
-; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32I %s
-; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64I %s
-; RUN: llc -mtriple=riscv32 -mattr=+f -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+f -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32I %s
-; RUN: llc -mtriple=riscv64 -mattr=+f -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+f -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64I %s
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32I %s
-; RUN: llc -mtriple=riscv64 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+d -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64I %s
 ; RUN: llc -mtriple=riscv32 -mattr=+f -target-abi ilp32f -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IF %s
diff --git a/llvm/test/CodeGen/RISCV/inline-asm-d-constraint-f.ll b/llvm/test/CodeGen/RISCV/inline-asm-d-constraint-f.ll
--- a/llvm/test/CodeGen/RISCV/inline-asm-d-constraint-f.ll
+++ b/llvm/test/CodeGen/RISCV/inline-asm-d-constraint-f.ll
@@ -1,7 +1,7 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32F %s
-; RUN: llc -mtriple=riscv64 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+d -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64F %s
 
 @gd = external global double
diff --git a/llvm/test/CodeGen/RISCV/inline-asm-f-constraint-f.ll b/llvm/test/CodeGen/RISCV/inline-asm-f-constraint-f.ll
--- a/llvm/test/CodeGen/RISCV/inline-asm-f-constraint-f.ll
+++ b/llvm/test/CodeGen/RISCV/inline-asm-f-constraint-f.ll
@@ -1,11 +1,12 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+f -verify-machineinstrs < %s \
+; NOTE: Assertions gave been autogenerated by utils/update_llc_test_checks.py
+; RUN: llc -mtriple=riscv32 -mattr=+f -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32F %s
-; RUN: llc -mtriple=riscv64 -mattr=+f -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+f -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64F %s
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32F %s
-; RUN: llc -mtriple=riscv64 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+d -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64F %s
 
 @gf = external global float
diff --git a/llvm/test/CodeGen/RISCV/mattr-invalid-combination.ll b/llvm/test/CodeGen/RISCV/mattr-invalid-combination.ll
--- a/llvm/test/CodeGen/RISCV/mattr-invalid-combination.ll
+++ b/llvm/test/CodeGen/RISCV/mattr-invalid-combination.ll
@@ -1,4 +1,5 @@
+; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
 ; RUN: not --crash llc -mtriple=riscv64 -mattr=+e < %s 2>&1 \
 ; RUN:   | FileCheck -check-prefix=RV64E %s
 
-; RV64E: LLVM ERROR: RV32E can't be enabled for an RV64 target
+; RV64E: LLVM ERROR: standard user-level extension 'e' requires 'rv32'
diff --git a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-emergency-slot.mir b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-emergency-slot.mir
--- a/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-emergency-slot.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/fixed-vectors-emergency-slot.mir
@@ -1,5 +1,6 @@
 # NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-# RUN: llc -mtriple riscv64 -mattr=+v -start-before=prologepilog -o - \
+# NOTE: Assertions gave been autogenerated by utils/update_llc_test_checks.py
+# RUN: llc -mtriple riscv64 -mattr=+v -target-abi=lp64 -start-before=prologepilog -o - \
 # RUN:     -verify-machineinstrs %s | FileCheck %s
 --- |
   target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n64-S128"
diff --git a/llvm/test/CodeGen/RISCV/rvv/large-rvv-stack-size.mir b/llvm/test/CodeGen/RISCV/rvv/large-rvv-stack-size.mir
--- a/llvm/test/CodeGen/RISCV/rvv/large-rvv-stack-size.mir
+++ b/llvm/test/CodeGen/RISCV/rvv/large-rvv-stack-size.mir
@@ -1,5 +1,5 @@
 # NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-# RUN: llc -mtriple riscv64 -mattr=+m,+v -start-before=prologepilog -o - \
+# RUN: llc -mtriple riscv64 -mattr=+m,+v -target-abi=lp64 -start-before=prologepilog -o - \
 # RUN:     -verify-machineinstrs %s | FileCheck %s
 --- |
   target datalayout = "e-m:e-p:64:64-i64:64-i128:128-n64-S128"
diff --git a/llvm/test/CodeGen/RISCV/select-const.ll b/llvm/test/CodeGen/RISCV/select-const.ll
--- a/llvm/test/CodeGen/RISCV/select-const.ll
+++ b/llvm/test/CodeGen/RISCV/select-const.ll
@@ -1,19 +1,19 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32I %s
-; RUN: llc -mtriple=riscv32 -mattr=+f -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+f -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IF %s
-; RUN: llc -mtriple=riscv32 -mattr=+experimental-zbt -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+experimental-zbt -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IBT %s
-; RUN: llc -mtriple=riscv32 -mattr=+f,+experimental-zbt -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+f,+experimental-zbt -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV32IFBT %s
-; RUN: llc -mtriple=riscv64 -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64I %s
-; RUN: llc -mtriple=riscv64 -mattr=+f,+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+f,+d -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64IFD %s
-; RUN: llc -mtriple=riscv64 -mattr=+experimental-zbt -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+experimental-zbt -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64IBT %s
-; RUN: llc -mtriple=riscv64 -mattr=+f,+d,+experimental-zbt -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+f,+d,+experimental-zbt -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck -check-prefix=RV64IFDBT %s
 
 ;; This tests how good we are at materialising constants using `select`. The aim
diff --git a/llvm/test/CodeGen/RISCV/select-optimize-multiple.ll b/llvm/test/CodeGen/RISCV/select-optimize-multiple.ll
--- a/llvm/test/CodeGen/RISCV/select-optimize-multiple.ll
+++ b/llvm/test/CodeGen/RISCV/select-optimize-multiple.ll
@@ -1,11 +1,11 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv32 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=RV32I
-; RUN: llc -mtriple=riscv32 -mattr=+d,+experimental-zbt -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv32 -mattr=+d,+experimental-zbt -target-abi=ilp32 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=RV32IBT
-; RUN: llc -mtriple=riscv64 -mattr=+d -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+d -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=RV64I
-; RUN: llc -mtriple=riscv64 -mattr=+d,+experimental-zbt -verify-machineinstrs < %s \
+; RUN: llc -mtriple=riscv64 -mattr=+d,+experimental-zbt -target-abi=lp64 -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s -check-prefix=RV64IBT
 
 ; Selects of wide values are split into two selects, which can easily cause
diff --git a/llvm/test/CodeGen/RISCV/spill-fpr-scalar.ll b/llvm/test/CodeGen/RISCV/spill-fpr-scalar.ll
--- a/llvm/test/CodeGen/RISCV/spill-fpr-scalar.ll
+++ b/llvm/test/CodeGen/RISCV/spill-fpr-scalar.ll
@@ -1,5 +1,5 @@
 ; NOTE: Assertions have been autogenerated by utils/update_llc_test_checks.py
-; RUN: llc -mtriple=riscv64 -mattr=+v,+d,+zfh \
+; RUN: llc -mtriple=riscv64 -mattr=+v,+d,+zfh -target-abi=lp64 \
 ; RUN:   -verify-machineinstrs < %s \
 ; RUN:   | FileCheck %s
 
diff --git a/llvm/test/MC/RISCV/mattr-invalid-combination.s b/llvm/test/MC/RISCV/mattr-invalid-combination.s
--- a/llvm/test/MC/RISCV/mattr-invalid-combination.s
+++ b/llvm/test/MC/RISCV/mattr-invalid-combination.s
@@ -1,4 +1,4 @@
 # RUN: not --crash llvm-mc -triple riscv64 -mattr=+e < %s 2>&1 \
 # RUN:   | FileCheck %s -check-prefix=RV64E
 
-# RV64E: LLVM ERROR: RV32E can't be enabled for an RV64 target
+# RV64E: LLVM ERROR: standard user-level extension 'e' requires 'rv32'