diff --git a/lib/Sema/CSSolver.cpp b/lib/Sema/CSSolver.cpp
index 764caaafb6a14..9f9c36667927c 100644
--- a/lib/Sema/CSSolver.cpp
+++ b/lib/Sema/CSSolver.cpp
@@ -1453,6 +1453,7 @@ bool ConstraintSystem::Candidate::solve() {
   // because it would assign types to expressions, which
   // might interfere with solving higher-level expressions.
   ExprCleaner cleaner(E);
+  CleanupIllFormedExpressionRAII cleanup(TC.Context, E);
 
   // Allocate new constraint system for sub-expression.
   ConstraintSystem cs(TC, DC, None);
@@ -1495,6 +1496,18 @@ bool ConstraintSystem::Candidate::solve() {
 
   // Record found solutions as suggestions.
   this->applySolutions(solutions);
+
+  // Solution application is going to modify AST, so we need to avoid
+  // clean-up, but let's double-check if we have any implicit
+  // expressions with type variables and nullify their types.
+  cleanup.disable();
+  E->forEachChildExpr([&](Expr *childExpr) -> Expr * {
+    Type type = childExpr->getType();
+    if (childExpr->isImplicit() && type && type->hasTypeVariable())
+      childExpr->setType(Type());
+    return childExpr;
+  });
+
   return false;
 }
 
diff --git a/validation-test/compiler_crashers/28593-unreachable-executed-at-swift-lib-ast-type-cpp-3771.swift b/validation-test/compiler_crashers_fixed/28593-unreachable-executed-at-swift-lib-ast-type-cpp-3771.swift
similarity index 80%
rename from validation-test/compiler_crashers/28593-unreachable-executed-at-swift-lib-ast-type-cpp-3771.swift
rename to validation-test/compiler_crashers_fixed/28593-unreachable-executed-at-swift-lib-ast-type-cpp-3771.swift
index 2d7b5b3a5765d..06a785dc0b637 100644
--- a/validation-test/compiler_crashers/28593-unreachable-executed-at-swift-lib-ast-type-cpp-3771.swift
+++ b/validation-test/compiler_crashers_fixed/28593-unreachable-executed-at-swift-lib-ast-type-cpp-3771.swift
@@ -5,6 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 [{_=#keyPath(t>w
diff --git a/validation-test/compiler_crashers/28623-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift b/validation-test/compiler_crashers_fixed/28623-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
similarity index 81%
rename from validation-test/compiler_crashers/28623-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
rename to validation-test/compiler_crashers_fixed/28623-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
index e3ec7a3ebaa14..2c333c7a2d636 100644
--- a/validation-test/compiler_crashers/28623-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
+++ b/validation-test/compiler_crashers_fixed/28623-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
@@ -5,6 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 f#keyPath(n&_==a>c{{{{{{{{{{{{{{{{{_=b:{{{{c{{{{{{d
diff --git a/validation-test/compiler_crashers/28631-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift b/validation-test/compiler_crashers_fixed/28631-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
similarity index 80%
rename from validation-test/compiler_crashers/28631-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
rename to validation-test/compiler_crashers_fixed/28631-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
index ae32b2f9ea681..ec248a45d86b9 100644
--- a/validation-test/compiler_crashers/28631-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
+++ b/validation-test/compiler_crashers_fixed/28631-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
@@ -5,6 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 [{{{{{{{{{{{{{{0=#keyPath(n&_=d
diff --git a/validation-test/compiler_crashers/28632-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift b/validation-test/compiler_crashers_fixed/28632-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
similarity index 83%
rename from validation-test/compiler_crashers/28632-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
rename to validation-test/compiler_crashers_fixed/28632-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
index c22489c5ad611..7cf03a0912d30 100644
--- a/validation-test/compiler_crashers/28632-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
+++ b/validation-test/compiler_crashers_fixed/28632-unreachable-executed-at-swift-lib-ast-type-cpp-1130.swift
@@ -5,9 +5,8 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
 // REQUIRES: asserts
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 
 {func a>
 print(a==#keyPath(a{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{{
diff --git a/validation-test/compiler_crashers/28635-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift b/validation-test/compiler_crashers_fixed/28635-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
similarity index 74%
rename from validation-test/compiler_crashers/28635-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
rename to validation-test/compiler_crashers_fixed/28635-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
index 82f3bc015f01a..e0aaea40dbae9 100644
--- a/validation-test/compiler_crashers/28635-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
+++ b/validation-test/compiler_crashers_fixed/28635-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
@@ -5,7 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 func a|Set(#keyPath(t>a>a{
diff --git a/validation-test/compiler_crashers/28639-unreachable-executed-at-swift-lib-ast-type-cpp-1337.swift b/validation-test/compiler_crashers_fixed/28639-unreachable-executed-at-swift-lib-ast-type-cpp-1337.swift
similarity index 80%
rename from validation-test/compiler_crashers/28639-unreachable-executed-at-swift-lib-ast-type-cpp-1337.swift
rename to validation-test/compiler_crashers_fixed/28639-unreachable-executed-at-swift-lib-ast-type-cpp-1337.swift
index 70b9a429a48cb..849688ae16ba6 100644
--- a/validation-test/compiler_crashers/28639-unreachable-executed-at-swift-lib-ast-type-cpp-1337.swift
+++ b/validation-test/compiler_crashers_fixed/28639-unreachable-executed-at-swift-lib-ast-type-cpp-1337.swift
@@ -5,6 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 print([{#keyPath(a}(t>A
diff --git a/validation-test/compiler_crashers/28640-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift b/validation-test/compiler_crashers_fixed/28640-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
similarity index 80%
rename from validation-test/compiler_crashers/28640-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
rename to validation-test/compiler_crashers_fixed/28640-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
index 40f87f57fa236..acaf2bc933c75 100644
--- a/validation-test/compiler_crashers/28640-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
+++ b/validation-test/compiler_crashers_fixed/28640-swift-tupletype-get-llvm-arrayref-swift-tupletypeelt-swift-astcontext-const.swift
@@ -5,6 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 protocol a func a|Set(#keyPath(t>a{
diff --git a/validation-test/compiler_crashers/28641-result-case-not-implemented.swift b/validation-test/compiler_crashers_fixed/28641-result-case-not-implemented.swift
similarity index 82%
rename from validation-test/compiler_crashers/28641-result-case-not-implemented.swift
rename to validation-test/compiler_crashers_fixed/28641-result-case-not-implemented.swift
index ef6976bfe3c51..d3370b0ab9172 100644
--- a/validation-test/compiler_crashers/28641-result-case-not-implemented.swift
+++ b/validation-test/compiler_crashers_fixed/28641-result-case-not-implemented.swift
@@ -5,7 +5,6 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
 // REQUIRES: asserts
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 {let β=b&[{{{#keyPath(n&[{{{{{{{{{{{{{{{{{{{{{{{{{{a{{{{s
diff --git a/validation-test/compiler_crashers/28642-swift-optionaltype-get-swift-type.swift b/validation-test/compiler_crashers_fixed/28642-swift-optionaltype-get-swift-type.swift
similarity index 80%
rename from validation-test/compiler_crashers/28642-swift-optionaltype-get-swift-type.swift
rename to validation-test/compiler_crashers_fixed/28642-swift-optionaltype-get-swift-type.swift
index 9fe9ea6a92851..c2e862abfb3e4 100644
--- a/validation-test/compiler_crashers/28642-swift-optionaltype-get-swift-type.swift
+++ b/validation-test/compiler_crashers_fixed/28642-swift-optionaltype-get-swift-type.swift
@@ -5,6 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 Array(_==#keyPath(t>Void!
diff --git a/validation-test/compiler_crashers/28645-swift-type-transform-llvm-function-ref-swift-type-swift-type-const.swift b/validation-test/compiler_crashers_fixed/28645-swift-type-transform-llvm-function-ref-swift-type-swift-type-const.swift
similarity index 80%
rename from validation-test/compiler_crashers/28645-swift-type-transform-llvm-function-ref-swift-type-swift-type-const.swift
rename to validation-test/compiler_crashers_fixed/28645-swift-type-transform-llvm-function-ref-swift-type-swift-type-const.swift
index f797ed802dbb5..26986fc8bd929 100644
--- a/validation-test/compiler_crashers/28645-swift-type-transform-llvm-function-ref-swift-type-swift-type-const.swift
+++ b/validation-test/compiler_crashers_fixed/28645-swift-type-transform-llvm-function-ref-swift-type-swift-type-const.swift
@@ -5,6 +5,5 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 (.n).h.n&[(#keyPath(t>A
diff --git a/validation-test/compiler_crashers/28646-swift-lvaluetype-get-swift-type.swift b/validation-test/compiler_crashers_fixed/28646-swift-lvaluetype-get-swift-type.swift
similarity index 81%
rename from validation-test/compiler_crashers/28646-swift-lvaluetype-get-swift-type.swift
rename to validation-test/compiler_crashers_fixed/28646-swift-lvaluetype-get-swift-type.swift
index 569bfa8082f85..772fd2340a16a 100644
--- a/validation-test/compiler_crashers/28646-swift-lvaluetype-get-swift-type.swift
+++ b/validation-test/compiler_crashers_fixed/28646-swift-lvaluetype-get-swift-type.swift
@@ -5,8 +5,7 @@
 // See https://swift.org/LICENSE.txt for license information
 // See https://swift.org/CONTRIBUTORS.txt for the list of Swift project authors
 
-// REQUIRES: deterministic-behavior
-// RUN: not --crash %target-swift-frontend %s -emit-ir
+// RUN: not %target-swift-frontend %s -emit-ir
 #keyPath(a
 print(Int
 print(_=#keyPath(a